Just for fun!
Check out this mathematical formula.
Engineers and scientists will never make as much money as business executives. Now a rigorous mathematical proof that explains why this is true:
Postulate 1: Knowledge is power
Postulate 2: Time is money
As every engineer knows, Work / Time = Power
Since Knowdledge = Power, and Time = Money, we have Work / Money = Knowledge
Solving for Money, we get: Work / Knowledge = Money
Thus, as Knowledge approaches zero, Money aproaches infinity regardless of the work done.
Conclusion: The less you know, the more money you make.Read More
On September 2004 I went to the central Pyrenees (Spain) with my wife. We don’t like arranged travels and we prefer to travel on our own, because we think is the only way you can get in touch with the real country and its people. This way of travelling is harder and more expensive than others, but also more pleasant, relaxing and, that’s the best, gives you a different point of view on the culture and way of life.
After my experience here you have my advice if you plan to travel on your own to the central Pyrenees. You have to understand that this is MY PERSONAL POINT OF VIEW and that it is not my intention to criticize the people or culture of the mentioned places. You also must take into account that these observations are from year 2004. Things might have changed (either in the right or in the wrong way) since then.
Travel to central Pyreness
Excellent / Specially interesting Very good / Very interesting Good / Interesting
Mediocre / Not very interesting Very bad / Not interesting
Click on it for pictures of the area Find hotels in this city / area Click on it for hotels in the city/area
This was a round trip to the central area of the Pyrenees, starting and ending at the city of Barcelona Find hotels in this city / area, because we have taken our car with us with the ferry from Mallorca Find hotels in this city / area. Although it would have been possible to get to the Aran valley, our first destination, in only one day, I preferred to split the way in two journeys and so start the holidays in a more relaxed way.
So, the first day we just moved from Barcelona to Cardona Photos of the area, a small village where the most interesting things are the impressive and well preserved castle on top of a hill, the ruins of a roman bridge and the salt mine. We have booked a room in the castle (Well, I should say that the castle now holds the excellent Parador Nacional de Turismo de Cardona ) and after a restful night we went to the old salt mine, with its curious and unique salt mountain . This mine is no longer in production and some of the corridors of the higher levels can be visited in a very interesting guided tour. I certainly recommend you this visit if you pass by Cardona.
From there we drove towards Solsona and then, by the C 14 road towards La Seu d’Urgell and Andorra. However a few km. before La Seu d’Urgell, at Adrall, we took the N 260 towards Sort Photos of the area where we stopped for a late lunch. Then, following the C 13 we drove up to the Port de la Bonaigua (2072 m) where you enter the Aran valley Find hotels in this city / area. A little after we arrived to Vielha (Viella), the capital city of the valley, and went directly to the Parador Nacional de Turismo de Viella , where we had booked a room for the following nights.
As I had already been in the Aran valley in the past, this time my main intention was not to visit the valley itself, but make some radial excursions. So, the following day we decided to go to the National Park of Aigüestortes Photos of the area for a short walk by the surroundings of the “estany” (lake) of San Maurici . We went with our car till Espot, where we had to park it because you can’t drive inside the park. However in Espot there is a regular service of 4×4 “Taxis” that for a reasonable price take you by the trails inside the park. In our case the Taxi left us near the Estany de Ratera (a small lake a few hundred meters above the Estany de Sant Maurici) and we went by foot till a close viewpoint where you can enjoy an incredible panoramic of the lake and the surrounding mountains. From there we walked down to the lake, by a narrow track that passes by the waterfall of Ratera, and finally bordering the lake leads to the Taxi’s stop, where we took the next Taxi down to Espot.
The next day we left Viella again and went south by the tunnel towards the Vall de Boi (Boi valley) Photos of the area, famous for the many Romanesque churches, most of them well preserved. Apart from the architectonic beauty of the small villages of this valley, its natural environment is also exceptional, and if you like open landscapes I can recommend you take the road that goes up to Taüll and the sky resort of Boi-Taüll, from where you will enjoy beautiful views of the valley.
We possibly planned a too short visit to the Boi valley (I hope to return there sometime and spend some days at least), but as we already had some hours left we drove by the N 260, passing by some semi-abandoned villages Photos of the area, and went to the close valley of La Vall Fosca Photos of the area. We had already been there some years before, so it just was a short visit in order to enjoy again the natural views that this valley offers.
The following day we had arranged a meeting in the town of Viella Photos of the area with a cousin of my wife, that by casualty was spending his holidays in Vall de Boi, together with his wife and their daughter. We spent the day visiting the town of Viella , doing some shopping and having lunch together.
Well, it was time to say goodbye to the Aran valley and move to our next destination, so we left Viella by the N 230 southwards and some km before Pont de Suert we took the N 260 towards the National Park of Ordesa. Near Castejón de Sos we made a short visit to the Benasque valley Photos of the area. In a few hours we drove by the road that follows the valley and got a first (and very positive) impression of what this valley was. It’s certainly in my list for some future, longer visit. Continuing our way by the N 260 we got to Ainsa and took the A 138 that leads to Bielsa by the banks of the Cinca river Photos of the area, where we took a narrow road that goes along the Pineta valley Photos of the area, at which end the Parador Nacional de Turismo of Bielsa is located. This is the most incredible place where a hotel can be, amongst the mountains, at the foot of the Monte Perdido and in the middle of one of the most beautiful corners of the Pyrenees, with no other buildings in dozens of km around. Some years before I had made a quick visit to the Pineta valley and I was very impressed, and now my dream of returning there for a longer stay in the Parador Nacional had come true!
The Pineta valley is at the east of the National Park of Ordesa Find hotels in this city / area, so the day after we decided to go to Torla Photos of the area, the natural entry of the park, and made some excursion by car by the surroundings (you can’t drive inside the park). When you get to Torla there is an incredible view of the town, up in a small hill, and the huge mountains of Monte Perdido in the background. The village of Torla itself is worth a visit, and the surroundings of the church are specially interesting, offering breathtaking views of the mountains.
From Torla we drove towards Bujaruelo Photos of the area, by a ground trail, along the Bujaruelo valley. This is a nice excursion either if you do it by car or by foot. From the trail you have excellent views of the mountains and the many water streams going down the slopes. Bujaruelo is actually nothing else than a mountain refugee beside a beautiful and well preserved roman bridge, but the environment is a dream.
When I had been in Ordesa, some years before, I made a nice excursion by foot, from Torla, along the ordesa valley, till the “Cola de Caballo”, a waterfall at the end of the valley from where one of the routes to climb Monte Perdido begins. This is a quite easy walk that I can certainly recommend you. The only drawback is the that you will meet hundreds of persons along the track…it’s not exactly what I would call a solitaire walk…
The following day we had planned a excursion by foot by the Añisclo gorge Photos of the area. This is a marvellous gorge carved by the Vellos river. There is a good track that goes up following the river towards the heart of the National Park, offering the spectacle of a virgin nature at its best. I have no words to describe this place…you will have to discover it yourself…
With the pictures of the Añisclo gorge still in our minds, the day after we had no other choice that leaving the marvelous central Pyrenees and drive towards Barcelona, however, we still had time for a short excursion by a narrow, but the good, road that goes up toward to the village of Plan Photos of the area. In Barcelona we took the ferry back home and back to everyday routine….but, fortunately, the Pyrenees are so close that I’m sure it was not the last time we spend our holidays there….Read More
On September 1998 I went to France Find hotels in this city / area with my wife. We don’t like arranged travels and we prefer to travel on our own, because we think is the only way you can get in touch with the real country and its people. This way of travelling is harder and more expensive than others, but also more pleasant, relaxing and, that’s the best, gives you a different point of view on the culture and way of life.
After my experience here you have my advice if you plan to travel on your own to France. You have to understand that this is MY PERSONAL POINT OF VIEW and that it is not my intention to criticize the people or culture of France. You also must take into account that these observations are from year 1998. Things might have changed (either in the right or in the wrong way) since then.
(Click on the icons to find hotels in that city or area)
If you are thinking of enjoying the marvellous french Riviera, change your mind. The well known “cote d’azur” is little more than about 80 Kms of overcrowded cost, and Saint Tropez Find hotels in this city / area, Saint Raphael Find hotels in this city / area, and Cannes Find hotels in this city / area are just another touristic resort.
Anyway, if you persist in the idea of visiting the area by car, avoid doing it on a weekend in Summer (as I stupidly did !). You will spent the whole day in a never-ending car bottleneck.
In our first lunch in France we found out that lunch-time in this country is rather different that in Spain. Restaurants in general close at 1:30 PM and after that time you can only eat some sandwich or crepe in the stands by the street….so you have to get used to have lunch earlier…:-)
Fortunately, at the end we reached Monaco Find hotels in this city / area. Monaco is worth to stay one or two days (But no more). In that time you can visit almost everything in this “little” exponent of how it must be “good life”.
A “must” in Monaco is the Oceanographic Museum. Everything there, from the Aquarium and museum to the building itself (built right on the cliffs), is outstanding. You can spent the whole morning there and then have a lunch on the restaurant on the terrace…
If you want to have dinner at a good restaurant at a resonable price (as “resonable” as prices can be in Monaco, of course) you can try the “Maison du caviar”, near Beausolei. Don’t get confused by the name of the restaurant, they have many dishes apart from caviar.
Hotels in Monaco Find hotels in this city / area are extremely expensive. A good alternative is to stay at hotel Olympia, wich is in Beausolei (France), but only a few streets away from Monaco and at a short walk from the Casino of Montecarlo. It is a small and recomendable hotel at afordable prices.
Unless you have a Rolls or a Ferrari don’t drive near the Casino….otherwise you will feel very, very “little thing”…
From Monaco we went to Grenoble Find hotels in this city / area. This city maybe is not woth the travel itself but it can be a good choice to spent a day in your way to Paris. Don’t forget to spend an afternoon visiting the surrondings, there are plenty of secondary roads leading to the ski resorts in the near Alps, that give you an excellent an pleasant view of the environment.
In Grenoble, don’t waste your time going to the cathedral, it’s just another building (and not one of the best, by the way..). Instead you can take the telepheric to “la bastille” from where, if you are lucky with the weather, you will enjoy a great panoramic of the city with the Alps at the background.
If you visit the city on the first tuesday of the month, don’t run to the shelters when you hear the raid-alarm at 12:00…it is just sounding as a conmemoration for the workers…the city is not being attacked…:-)
A good hotel to stay there (always within my reduced budget) is the Hotel D’Angleterre. They also offer you an interesting discount in the public parking nearby and in the tickets for the telepheric to “la bastille”.
Another day of driving and we got to Paris. This is for sure one of the most beautiful cities in the world…and it is not a topic…it is true…At least once in your life you must visit Paris Find hotels in this city / area.
One of the problems of Paris is the dense, and somehow chaotic traffic. The best thing you can do if you go by car is to search a parking near the hotel and leave it inside as long as posible.
In Paris, get ready to pay for everything. Don’t expect to do anything apart from walking down the Boulevards and visiting churches without paying….even using the toilettes in the bar will cost you 2 francs.
The best way to move accross the city is of course the underground. You can buy a special ticket for visitors called “Paris Visite” that can be used for a certain number of days (1 to 5). Just remember that the day you buy it counts as a full day…I mean that if you buy a 2 day ticket at 23:00 it will be usable only for 25 hours….so you had better get it early in the morning…
Just a comment regarding the bars. While in Spain one of the cheapest thinks you can drink is a mineral water, it seems that in Paris water is for tycoons.
Be ready to pay 20 to 30 francs for a 1/4 L. bottle…..Coffe is about half that price…
I recomend you spend one day visiting Versalles….not the city of course, but the palace and the gardens…..you will understand then why the French revolution took place…
I you get to Versalles and find all the stores closed that is because it’s Monday….curiously, almost all the activity of the city is related to the visitors of the palace….and it can’t be visited on Mondays…
Well, you haven’t planned very well your visit and won’t be able to watch the marvels the palace hides inside,..sic….but be happy !!, you can still visit for free all the surroundings and walk the gardens down to the lake almost alone…something you can’t certainly do the rest of the week….Believe it or not, I HAVE taken some pictures of Versalles WITHOUT any person!!…very little tourists can say that…:-)
Another thing about Versalles…don’t forget to take with you some pieces of bread….otherwise you won’t have the chance to feed the big fishes (carps I think) which are used to take the food from the hands of the visitors, as if they were dogs…
If you are going to go up to the tower Eiffel you should know that you can do it for free, (by the stairs, of course…:-)…but you can also take the lift (a “little” more expensive, by the way)….If you are planning to go the “third” (highest) floor and when you get to the tower you see a banner announcing that the “third floor is closed”, don’t worry….it simply means that it’s closed at “that moment”…. they will posibly open it half an hour later or before….Just stay on the queue and buy your ticket for the “top floor”. The view from top of the tower is worth both, the wait and the price…
I am not going to recomend you to visit anything in special. There are great travel-guides of Paris and in fact EVERYTHING is worth being visited….(even the really nice church we had near the hotel, that was not even mentioned in any guide, and that could be considered as a cathedral in many other cities). Don’t plan to stay less than 5 days in Paris…in that time you will only have time to have a first look at the most outstanding places….
In spite of the fact that I loved Paris very much, I have to admit that I get fed up of big cities very soon, and we decided to have a few days rest before going back home. So we went to the central part of France, where many health resorts of thermal waters are famous, in the region of Auvergne.
To be more exact we spent two days in the small village of Mont Dore. The charm and beauty of the landscapes, together with the peace and silence of the villages make of this area one of the most remarkable places to rest.
A recommendable hotel in Mont Dore is Hotel Le Panorama….As its name indicates it has a nice view on the village and down the valley…it is extremely quiet and you can spend some of your time at the swimming pool, playing ping-pong or billiard, or just sitting at the hall smoking a cigar while watching the rain through the large windows. Although I liked very much the location and facilities of this hotel, I can’t say the same about the rooms and the staff….they both need to be “updated”.
If you get worn-out of all this I recommend you take your car and visit some of the pretty medieval villages of the surroundings, and enjoy their regional cheeses and sausages.
No far away there is also a small but curious farm of kangaroos and castors…You can take pictures, touch and feed the animals…something different from the usual zoos..isn’t it?. It’s cheap and you, your companion and the children can have a nice experience with these “wild” animals.
Also, in the hotel itself, there is the restaurant L’Oree du Bois where you can taste some of the marvelous local dishes before going back home.
This is a simple telnet client specially developed for accessing the chats of ON4KST when you can’t (or don’t want) to use the WEB interface. I made this software for my own use because in my radio QTH by the countryside I only can access the Internet using the GPRS mobile phone. The cost of this service (at least in Spain) depends on the number of bytes sent/received, so using the WEB interface was simply too expensive. On the other hand, standard telnet clients did not offer the functionalities and formatting options I wanted.
You can download and use this software for free for your own private use, however please understand that I don’t offer any kind of support and I don’t promise to develop new versions in the future. Anyway if you have some comment you can always E-Mail it to me.
After downloading the setup program you simply have to run it to install the application. Then you will find a new “KSTchat” option in the “Start” menu of Windows. (IMPORTANT: If you already have an older version of the program you MUST uninstall it before running the setup of this new version. VERY IMPORTANT: You MUST place the downloaded setup program “KSTClient_Setup.exe” in an EMPTY folder, then with Windows Explorer open that folder and double click the file in order to run the installation)
In the folder where you have installed the program (by default it goes to C:\Program Files\KSTclient) you will find 4 files:
KSTClient.exe is the executable program.
KSTClient.ini is the file holding the configuration parameters (Do not change it unless you are sure of what you are doing)
KSTClient.html is the file containing the basic explanation of what KSTClient is.
Warning.wav is the sound file to play when a new “watch text” is detected.
Enjoy it! See you in some of the ON4KST’s VHF or EME chats.
Changes in version 1.5:
DX-Spots containing the < and > characters where not properly shown (like “JM19JN01”).
A welcome screen is shown on program start-up, providing some basic information about the program.
Changes in version 1.4:
Support of Internet Explorer 7. After installing this version of I.E. the “Automatic alignment” function did no work in former versions.
Changes in version 1.3:
The program was slowing down the system after being connected for a long period.
Possibility to change the font, its size and also the space between lines (modifying the INI file)
Possibility to choose whether the program must always align to the bottom of the texts (normal mode when watching the chat) or not (for reviewing past messages)
Changes in version 1.2:
Fixed a possible bug that made the program hung during start-up and before connection.
Changes in version 1.1:
Other user requests:
Warning sound could not be disabled in former version.
Possibility to decide whether or not the watch texts should be searched in the chat prompt.
Connection by IP address was not sending the login automatically.
A few other minor bugs.
- 4 way 50 Ohm splitter
- 2 way 50 Ohm splitter
- HF-400 coax relay
- SSB-Electronic LNA-145 low noise preamplifier (MGF-1302)
- 8 M2 2M5WL antennas (aprox. 23 dBD gain)
- Bird 43 power meter
- Antennaworks power amplifier (8877)
- 70w driver brick amplifier
- Tohtsu CX520D coax relay
- Kenwood TS-790E transceiver
- Coax. “T”
- SSB-Electronic K-2001 144 MHz to 28 MHz converter
- RFspace SRD-IQ software defined receiver
- Timewave DSP-599zx audio filter
- Heilsound Pro Set Quiet Phone headset
- Communications speaker
- AR2 TRS04VD Transmit/Receive Sequencer
- West Mountain Radio Rigblaster plus digital communications interface
- Heathkit uMatic keyer
- DELL Latitude D630 laptop (Core2Duo 2.4 GHz, 2Gb RAM), running Windows XP professional
- 22″ ACER monitor. Connected to the laptop as a secondary monitor, so I can use both the 22″ and the laptop monitors simultaneously.
- Linrad. Software Defined Receiver software, showing a 160 kHz bandwidth. Allows to monitor the whole EME segment simultaneously.
- VAC (Virtual Audio Cable). Reroutes the audio output of Linrad (22) to WSJT (24), internally without cables.
- Instance #1 of the WSJT program, just for decoding the signals received by Linrad
- Instance #2 of the WSJT program, used to decoding the signals received by the TS-790 and also for transmitting.
On September 2007 I went to Denmark (see map) with my wife. We don’t like arranged travels and we prefer to travel on our own, because we think is the only way you can get in touch with the real country and its people. This way of travelling is harder and more expensive than others, but also more pleasant, relaxing and, that’s the best, gives you a different point of view on the culture and way of life.
After my experience here you have my advice if you plan to travel on your own to these areas. You have to understand that this is MY PERSONAL POINT OF VIEW and that it is not my intention to criticize the people or culture of any of the mentioned places. You also must take into account that these observations are from year 2007. Things might have changed (either in the right or in the wrong way) since then. You must also bear in mind that this is not a travel guide, but just the description of my own journey and my own impressions. If you don’t agree with some of the opinions below just write your own WEB page with you own opinions, but don’t bother me.
Excellent / Specially interesting Very good / Very interesting Good / Interesting
Mediocre / Not very interesting Very bad / Not interesting Click on it for pictures of the area
The main idea of this journey was to visit Denmark, where we had never been before. When planning the journey it was obvious that we’ll have to spend some days at Copenhagen, but it was difficult to decide what other places in the country would be worth to visit. Finally, taking into account the few days we had and the fact that we were arriving and leaving by the airport of Copenhagen we decided to concentrate on the islands, leaving most of the continental part (Jutland) for a future travel.
I found a relatively cheap direct flight from Palma de Mallorca to Copenhagen in Lastminute.com with Spanair . The flight lasted for about 3 hours and when arrived we went directly to get the car I had booked at Budget . I had booked a Peugeot 307 SW, but as they didn’t have any available I was given an Audi A4 Avant for the same price (no need to say I didn’t complain…).
And there the problems began…. suddenly I realized I had forgotten the travel guide in the seat of the airplane. I immediately went to the customer service of SAS (the partner of Spanair in Denmark) and they “kindly” told me that nothing could be done. That the airplane had been already cleaned and that it was not their responsibility (!!). The girl told me that I should go to the lost and found department of Copenhagen police !!. Well, buying a new guide would solve the problem, so after my initial anger I decided it was better to forget the incident, take the car and drive towards the city.
We went directly to the Hotel Avenue that I had booked in hotusahotels.com . This hotel is not at the centre of Copenhagen, but this was not a problem for me as I would have a car. The hotel itself was good for me, it offers free WiFI to guests, the crew was always very helpful, room and bathroom are clean (but both very small) and you can use their car park for an reasonable fee. The only drawback was the price of the room, but this is the same for all hotels in Denmark. They are terribly expensive, specially if you are from a country like Spain, where you are used to get the same (or even better) quality and services for half the price.
It was getting late for lunch so we just left the baggage in the room and went to a cafe nearby (the hotel doesn’t have restaurant) to eat one of the traditional Smorrebrod (a toast with salad and fish/shrimps or meat) that the Danes like so much to eat at lunch. Afterwards we went to the downtown to to have a first feeling of the city and walking a bit by the famous Strøget , that is said to be the longest shopping street in Europe. To the disappointment of my wife all shops were already closed at that time (Almost all shops in Denmark close at 17:00 !)
The following day was Sunday, so we decided to visit the downtown of Copenhagen Photos and information of the area as it would be easier to park than in a working day (and free!). Driving by the city of Copenhagen is not complicated, but parking in the old town is really expensive (free on Sundays), and understanding the complicated signals that supposedly tell you where and when you are allowed to park (depending on the day, time, etc.) is simply impossible for a foreigner. And fines are not cheap, believe me…. I strongly recommend you don’t get to the downtown in you own car in working days!
We went directly to the most important attraction of the city, the Little Mermaid , that although not being specially impressive is an icon of Denmark and thus you are supposed to visit it. We left the car at the car park near the Little Mermaid and walked to the near downtown, passing by the really beautiful Saint Albans church and the Churchill park, to end up in the impressive Marble church and the Amalienborg palace . From there we walked towards the Rosenborg castle , that is surrounded by a beautiful park, and then to the botanical garden Photos and information of the area, that is absolutely splendid and holds a huge greenhouse that is worth the visit.
It was getting late, so we went to Nyhavn , one the most popular corners of the city, and where there are plenty of restaurants with terraces along the channel. After lunch we took one of the open boats that leave from Nyhavn itself and offer one-hour cruises by the channels and harbour . This gives you nice view of the city for a reasonable price and we certainly enjoyed very much the experience.
Next day, Monday, it was time for some shopping, so we spent the whole morning going up and down by the Strøget, buying some amber (quite expensive, by the way) and other souvenirs. In the afternoon we went to the famous Tivoli gardens Photos and information of the area, a amusement park in the central Copenhagen, that in spite of its reduced size (about 75,000 sqr. meters) catches you for many hours. Tivoli is specially beautiful in the night, when it’s illuminated by thousands of coloured lights, so it’s a good idea to get there in the afternoon and stay till late in the evening, having dinner in any of the multiple restaurants, that cover all tastes and budgets.
The following day we left Copenhagen towards northern Zealand (the island where Copenhagen is located), driving by the coast road that takes you through a never-ending succession of houses that hardly allow to see the sea (the Oresund sound, that separates Denmark and Sweden). We got to the Kronborg castle Photos and information of the area, near Helsingør, that is specially famous for being the setting for much of William Shakespeare’s famous tragedy Hamlet, Prince of Denmark. From there we continued northwards by the coast to the village of Gilleje , and then went south to the Fredensborg palace Photos and information of the area, that we only could see from outside (It is the Danish Royal Family’s spring and autumn residence). A little further there is the impressive Frederiksborg palace Photos and information of the area, that we have to visit very quickly as it closes at 17:00 (as almost every place does in this country, grrrr!!). In order not to go back to the hotel so early we drove eastwards to the village of Hundested and spent some time walking in the sunset by the beaches nearby Photos and information of the area.
Wednesday was a rainy day but we had to go on with our plans, so we took the car and crossed the 16 km. long bridge that links Denmark and Sweden, spent some time in the city of Malmö Photos and information of the area, with beautiful parks and many pedestrian streets, and then went to Lund Photos and information of the area, one of the oldest towns in Sweden which has a beautiful cathedral. From there we drove down to the southern coast and went back to Malmö by the road along this absolutely flat coast of the Baltic sea. Crossed the bridge again and went back to the hotel with a really bad cold I had got….
Next day it was time to move to our new destination in the island of Lolland, but instead of going directly there (distance is really little) we stopped at Roskilde Photos and information of the area, which has a beautiful cathedral, nice pedestrian shopping streets, and a famous Viking ship museum. Then went down to Næstved Photos and information of the area, where we had lunch, and then to the beautiful Gavnø palace Photos and information of the area, that lays on its own island, and that we could only see from outside (do you guess why?…yeees, it closed at 17:00 !!)
Just before sunset we arrived to Maribo, the main town in Lolland island, and went to the Hotel Maribo Søpark , where I had booked a room. The problems began when they told me that there were no smoking rooms available, and in spite of me insisting that I had booked a smoking room I was forced to get a non-smoking one, what certainly exasperated my wife (the smoker..). The girl at the reception was kind enough to provide us with an ashtray an grant us permission to smoke at the balcony of the room (no need to say how “pleasant” was to smoke outdoors, in the fall, in Denmark, in the evening…). Regarding the room and the bathroom, well…. they should be fine in the 80’s, but little had been renewed since then…. The leather of the chairs was worn out, the sheets were broken, the curtain of the old bath tube was dirty, the balcony hasn’t been cleaned for ages and it was full of spiders,…….. The only good point of this hotel is the location, right at the shore of the Søndersø lake, with nice views and in a restful place. Let’s say it’s the wrong hotel in the right place, and it’s certainly not cheap at all.
Maribo Photos and information of the area is a small town with no special tourist interest, however its location in central Lolland, by the shore of the charming Søndersø lake Photos and information of the area, makes it an interesting place to stay when visiting this most rural, and somehow less developed, region of Denmark.
A few km. north of Maribo you can find the excellent Knuthenborg safari park Photos and information of the area. If you are travelling with children the visit to this park is a must, but anyway if you like enjoying the nature and animals you should also consider spending at least one morning there. You can take a bus at the main entrance, but definitively the best way to visit the park is with your own vehicle. The ticket is not cheap, but it’s worth the money.
The next day we drove to the east of the island of Møn, where Møns Klint is located. If you like natural landscapes I strongly recommend you visit Møns Klint Photos and information of the area, a famous natural resort with over 100m high bright chalk cliffs, on top of which a beautiful forest invites you to walk along the well preserved (although quite steep) footpaths that go along the coast for several km.
It was time to move on, so the following day we took the ferry that links the islands of Lolland and Langeland (there is no bridge between these islands) and from Langeland we crossed the bridge to the island of Fyn, driving directly to the city of Odense Photos and information of the area, where the most outstanding is the house of Hans Christian Andersen and the traditional houses of the neighbourhood Photos and information of the area. There are also many pedestrian shopping streets in the downtown, but this time we only had very little time to walk around.
When I was planning this travel my intention was to stay in a hotel in Odense, but for some reason there were no rooms available in any suitable hotel, so I finally booked a room in the Hotel KongebroGaarden in Middelfart Photos and information of the area, right at the shore of the narrow sound between Fyn and the mainland. The Hotel KongebroGaarden is a good hotel, with comfortable and excellent, although pretty small rooms, some of them with views of the Lillebælt sound.
Our journey was getting to its end, but still had one day left for a visit to the charming city of Ribe Photos and information of the area, in the mainland, known for being the oldest city in Denmark and for having more than 100 traditional well preserved houses. I enjoyed very much spending the day in Ribe and walking up and down by the pedestrian streets.
In the afternoon it began raining a lot, so we went back to the hotel early and rested a little in our last night in Denmark. The last day we crossed the island of Fyn eastwards, stopping again in Odense for some last-minute souvenir shopping, crossed the 18 km long bridge that links Fyn and Zealand islands and went directly to the airport of Copenhagen.
Copenhagen is a really worth a visit and there are also other interesting (but isolated) spots all over the country, but the landscapes and coasts that we visited somehow disappointed me a little (the only exception was Møns Klint). Might be it has to do with the fact that this is a very flat country, with no mountains at all (highest is about 170 m above see level only) and also because of the too domesticated nature.
The Danes are very polite and they are always willing to help you as much as they can. They are really nice people.
The food is quite different to what we are used in the Mediterranean, so it was really hard to get used to it (in fact we didn’t manage to get used to it). Most dishes are based on fish or meat, with very little vegetables.
The different lunch and dinner habits were also a problem (they use to have a relatively light lunch and a strong dinner). My wife is vegetarian and her opinion about the Danish food was even more radical than mine…. her words were “thank goodness there are Italian restaurants everywhere….” 🙂
Alcoholic drinks are VERY expensive. There is no Danish wine (too north for the vines), but fortunately there are many different good beers (very expensive, but good).
The following discussion about the influence of the polarization of signals and ground gain took place in the moon-net. I found the subject so interesting that I decided to put together all the messages in this page.
What causes the so called “ground boost” when moon is low above horizon? Is this effect frequency and/or polarization dependent?
Ground boost, or ground-reflection gain, is caused by reflection from the earth. It is polarization-dependent in that the ground tends to reflect horizontal waves better than vertical. At VHF/UHF, it is not very frequency-dependent, but on receive the earth is noisy so at low elevation angles, you’ll pay a price in noise at 70 cm. At 2m, whether the noise increases at low angles depends upon the man-made noise level at your QTH.
On 5-Mar-2002 OZ1RH wrote:
Answered in my lecture on Ground Gain for eme, link from www.oz1rh.com
My findings are that the ground gain is not dependant on polarization. I have yet to find a time where there is a difference between horizontal and vertical and I do make it a point to check this every time I get ground gain (=very often on my setting moon). The same enhancement is always present in both planes.
Peter, SM2CEW wrote:
> My findings are that the ground gain is not dependant on polarization. I
> have yet to find a time where there is a difference between horizontal and
> vertical and I do make it a point to check this every time I get ground
> gain (=very often on my setting moon). The same enhancement is always
> present in both planes.
I agree that ground gain is not different for V or H polarisation. I afraid Peter’s statement can be misunderstood so I will try to make it very clear:
I have studied what happens when the total Faraday on my own signal is 0 (or 180) degrees. This means I have made observations when my own echoes are strong in the same polarisation that I use for tx and very weak or absent in the orthogonal polarisation.
What I observe is that if the moon is high, the echo H to H is exactly the same as the echo V to V. (strongest “O” in 2 minutes about +/- 1dB accuracy)
BUT, if the moon is low, so I send (and receive) well to an angle downwards that fits the mirror image of the moon on the ground I observe sometimes that the H to H signal is much stronger than the V to V signal. The difference is in the order of 10dB or more. About 5 to 10 minutes later the relative levels has reversed, V to V is very much stronger than H to H. ( Halfway between these two extremes the two polarisations are equal)
What happens is that the signal from the mirror image can equaly well enhance or degrade. When it is in phase it will add, but when it is at 180 degrees it will subtract!! (And cause ground loss)
When a H wave is reflected, the phase is changed by 180 degrees, but when a V wave is reflected, the phase is unchanged. Therefore, at the moment of max ground gain for H pol, there is maximum ground loss in the V pol and vice versa.
There is (theoretically) some difference between the ground reflectivity for H and for V. Practically I have not observed that. The difference is small at angles below 10 degrees with the type of ground I have around here.
Theoretically there is no limit for how much ground gain one can get. (Imagine a valley that happens to have parabolic shape!) Practically one can expect 3 to 5 dB which makes a really dramatic difference on own echoes for which the gain comes twice!
Ground boost is extremely useful for small antennas but already for a 4-yagi array the time it lasts is too short for it to be of much practical use. With a small antenna and variable height or variable polarisation ground boost can be used for an hour or two at a time.
Peter is right. There is no theoretical reason for difference in polarization. Simple question is: What will happen to the circular polarization –> decomposition to the linear vector ? how the phase shift will happened?
Thanks to Palle and Peter for their insights and further information. It’s interesting that results obtained using vertical polarity seem to differ. Probably that has something to do with differences in terrain and ground conductivity at the various stations. We can’t all have flat sea water (6 dB ground gain)!
There is no question that Peter and Paul are misleading the members of this list.
The theory is as follows:
“mirroring” (From standard textbook on electricity)
Assume a small charge Q at a small distance above a very large flat conducting surface. To solve Maxwell’s equations for the electric field above the surface one can place a mirror charge -Q (opposite charge) below the conducting surface and then solve Maxwell’s equations for the two charges with the conducting surface removed. The solution one gets above the plane from this method is the correct electric field from the single charge above the plane. Below the plane the field is zero of course. The mirror charge is a tool to solve the equations easier.
Now apply this theory to a horizontal antenna. Let us look at one of the electrons that oscillates back and forth 144 million times a second in a dipole that is at a height H above a very large flat conducting surface. To find the far field we replace the conducting surface with a mirror dipole placed at -H (below the ground) and we put a positron in the mirror dipole that moves synchronous with the electron. When we analyse the radiation from the two dipoles we find that the electromagnetic field has opposite sign because the sign of the charges is opposite. An electron moving to the left or a positron moving to the right both mean current flowing from left to right!
For a vertical dipole we do exactly the same. This time the result differs because when the electron moves downwards, the positron moves upwards. When looking at the dipoles from far away one will observe the particles move in antiphase so because of their opposite charges the corresponding currents are in phase.
When observing a dipole above ground at an angle that makes the distance difference to it’s mirror image zero or any integer number of wavelengths, the radiation from vertical dipoles will add while the radiation from horizontal dipoles will cancel.
This is not “just theory” I can not say for sure what “mistake” Peter did, but I have studied the phenomenon very carefully here. The ground where the reflections happen here is flat farmland. And I can very clearly observe a minimum (really weak signals) in one polarisation while there is a ground gain maximum in the other polarisation.
Maybe, for example, if there are many threes growing on the ground, the refractive index will be different for horizontal and for vertical waves. This means that the wave speed is lower for vertically polarised radiation. This could be the explanation for Peter’s findings.
I have offered to give my lecture on ‘Ground gain and radiation angle at VHF’ in Prague, but no answer yet from the organisers. The lecture might be a starter for the discussion, as I do not know too much about the Brewster angle. See www.oz1rh.com , please read the Word-document as the html version lacks some formatting.
Quote from Chapter 5 Polarization and ground effects:
“For DX-ers on HF it is well known that the radiation angle of a horizontal polarized beam is a function of its height over the ground and ground conductivity has little influence on low angle of radiation. Things are different for vertical polarization. A vertical antenna needs perfect ground to give low angle of radiation. In fact is does not radiate at all below an angle called the Brewster angle. This angle is dependent of the conductivity of the reflecting ground. Check an antenna book on verticals for 80 m, the 80 m DX’ers know all about this. Does low angle of radiation interest us for VHF? Yes ground gain is happening in the range of 0-10 degrees.
Ground gain for one reflection 5-6 dB
Ground conductivity Little influence at low angles
Lossy ground Little less ground gain and not so deep nulls in pattern
Good ground conductivity (salt water) Deep nulls in pattern, but peak almost uninfluenced
Ground gain for one reflection Perhaps 3 dB
Ground conductivity No radiation below Brewster angle 5-20 degrees
Lossy ground High Brewster angle 20 degrees?
Good ground conductivity (salt water) Low Brewster angle < 5 degrees?
It seems a good idea to use horizontal polarization if one wants low angle of radiation. Vertical polarization has less ground gain. A circular polarized signal contains two components: a horizontal polarized and a vertical polarized one. Ground reflection influence the two components differently as describes above and after ground reflection the signal is no longer circular but somewhat elliptical polarized at low radiation angles.”
I am certainly no expert in any of this, but I encourage you to spread the information about ground gain. Many folks seem to be confused about it. All I can tell you, is that on 6m EME, everything is so marginal to begin with, that at least one station MUST have ground gain, and of course, if both stations have ground gain, it is all the better.
I still receive inquiries from 6m stations, for example, who ask for suggestions about elevating their one or two small yagi arrays. Their single yagi pointed at the horizon acts like 4 yagis, and 75% of the time cndx are not favorable enough for a contact even then. Such stations certainly cannot afford to “throw away” such ground gain and elevate their antennas! In most cases, a single 9 element yagi pointed at the horizon has the effective gain of my 4 yagi 6m array, and since I hear my own echoes over half the time while pointed up at the moon, it should be just a matter of time until I can contact anybody who can hear their own echoes on the horizon.
Ground gain with a single yagi can be a wonderful thing! As so nicely illustrated by the charts on your website, a single yagi has muliple ground gain lobes, providing muliple chances at EME contacts as the moon moves in front of the different lobes. At least on 6m, it seems we need as many chances as we can get – HI! And I have been simply AMAZED at the difference it makes when an antenna points at a salt water horizon! The smallest stations I have worked on both 2m and 6m EME have had single yagis looking over a salt water horizon. The books may say that there are only a couple dB to be gained from salt water compared to average ground….but I am here to tell you that every last dB makes a HUGE difference when you are involved with a very marginal EME situation.
I found on 6m EME with my 21m long single yagi 21m above ground, that my third lobe up at 18 degrees was the same gain as my free space gain (when it was elevated). By leaving the antenna pointed at the horizon, I had significantly more gain in my first (4 degrees) and second (11 degrees) ground gain lobes, and I was able to make a number of contacts using the second lobe. I might also point out that I have noticed that, especially on 6m, there are many factors that can “interfere” with the propagation of the signal to the moon and back. Most of these factors (ionospheric scattering and refraction, tropospheric ducting, etc.) are more of a factor the lower the angle of radiation (and the more atmosphere/ionosphere the signal has to pass through). On a number of occassions I have noticed good signals from horizon stations when the moon was high enough to be up in front of their second ground gain lobe, but I have heard NOTHING when it passed in front of their main antenna lobe.
Long live the big single yagi pointed on the horizon, with its higher ground gain lobes! Good luck in spreading more information about this very important subject! MNI TNX and VY 73, Lance
Leif, When I get groundgain I beam out over water, a very far stretched lake, nothing is obstructing the path. I do not se the cancellation you see in the opposite plane. When I have GG in one plane I see the same thing in the opposite. Ever since you mentioned this, quite a long time ago, I have made it a point to check as I had not seen the same results. Never have I seen the effect you see. It could be due to the fact that I use 3 yagis high in my stack and have a narrower lobe than you, hence see ground gain at a lower elevation (typically start seeing it at 3 deg and lower).
So, if I am misleading the group because of the real world not matching the text book, I am sorry to say that I will stick to my story.. Hi !
Thank you for very good explanation. There is still something I do not understand.
As far as I understand your explanation lead to the conclusion that interference pattern for horizontal and vertical polarization will be different. This is for the case when one dipole is excitating electromagnetic field. One dipole has omnidirectional radiation pattern. For large number of dipoles it will be superposition of the EM fields and the pattern will be more complicated depending on the distances between dipoles ( field sources ) versus wavelength. It is even more different if the magnitudes and phases of those sources are not equal.
In case of ground gain I am thinking about reflection of the wave radiated from high gain antenna having almost plane phase front. Reflection occurs at the large distance from the antenna and the surface of the reflector ( ground ) is also large versus the wavelength. The antenna can be very low above the ground or very high above the ground. There will be also space attenuation in near field between antenna and reflector ( ground) which has to be considered. This will generate some additional sidelobes which levels depends on the height of the antenna above the ground. In this case I would rather apply optics law. Assuming ideal reflector there, will be no difference for polarization. But the ground – soil is not a perfect conductor, so it could be some difference depending on the ground properties. Salt water is much better almost ideal for this case.
Long time a go at my first work ( back in Poland ) I had to do with the satellite C-band feed systems for 32 m dish using so called light-guide which is similar to the waveguide, but the dimensions are much larger then wavelength, about 2 by 2 meters. This arrangement was at the base of the antenna , guiding waves vertically. There was one flat mirror at the top, changing angle with elevation of the dish. This reflector fed tapered circular waveguide which ended with corrugated feed horn illuminating Cassegrain subreflector. The primary feed at the basement was radiating on flat metal surface with very small angle causing reflection in some degree similar to the case of the ground gain. The feed had two linear polarizations one parallel with the light-guide surface and second orthogonal. Those two signals were amplified and combined in order to obtain 4 different polarizations: Linear horizontal, linear vertical, circular left and right.
Ohio State University Radio Astronomy Observatory had large antenna ( Big Ear built by Prof. John Kraus W8JK ) which consists of the feed system illuminating fixed mounted sector of the parabolic reflector ( looks like a wall ) about 250m wide and 40 m high ( I do not remember exact dimensions). This reflector focused the beam and next illuminate large flat reflector which was tilted in order to obtain required elevation angle. From the beginning the main feed system consists of the pyramidal feed horns. But the problem was the noise temperature picked up from the ground. Then they modified the antenna: the surface between feed and parabolic reflector was covered with sheet metal and what is important here they modified the feedhorns in order to accommodate radiation pattern to the ground gain. And again they use all four polarizations: linear horizontal, vertical, right and left hand circular. Unfortunately I learn that this instrument does not exist any more and there is a golf corse now at this place ( generating income).
Similar radio telescope exists in Nancay France built by Hevre’s F5HRY father. The difference was in ground reflector, Nancay instrument has some metal mesh screens at he certain angle to the ground in order to lower ground noise contribution, but not use beam forming obtained the same way as in Ohio.
My own observations are based on 432 MHz EME experience. I never could figure out the difference in ground reflection for linear polarization horizontal or vertical on 432. The difference was caused by the Faraday rotation. Some times I had echoes on opposite polarization or distorted to elliptical, but I never detected weaker echoes on transmitted vertical compare to the horizontal polarizations. Ground reflection has to do with the reflection properties of the ground, which might be different for different frequencies..
I am maybe wrong, this is very interesting subject. All comments are very much appreciated.
I wonder if the ‘ground gain’ you are seeing Peter is really the ground or just ionisperic focusing (scintillation). My findings indicate that single yagis or equivalent get good ground gain but once you stack except in rare terrain situations, you won;t get ‘ground gain’ because the H plane pattern is so narrow that the antenna pattern never gets to the ground at a point where ground gain is the result. i have never seen ground gain with any eme array and that includes my 6m array of 4 x 6m7JHV yagis wher the bottom yagis are just 10 feet ( half wave) over ground and the top pair were at 35 feet. echoss are the same from straignt up all the way down to moon dissappearance over the horizon. my 2 wavelentgh Yagis at 45 feet high however gets good ground gainat 4 to 6 degrees and never lower. i have repeated this 6m result at three different locations.
Polarization is defiinitely a factor in ground gain. Horizontal antennas see the ground as a reflecting surface paralell to their polaration. Vertical antennas see the earth as a cross polarized element so ground reflection is minimal. Brewster angle effects may cause some vertical polarization enhancement.
These effects are what I and others have noticed and do not necessarily agree with the computer analysis of the system. However, moon echos are a pretty good sign of where your radiation angle is. this is one area where I feel the computer simulation falls apart.
Remember my old 4×14 at 5.2m stacking distance?
Sidelobe level was only -8 or -9 dB. I had very good ground gain when the sidelobe hit the moon via ground reflection while the main lobe hit the moon directly:-)
Overstacking does not reduce the gain, it creates strong sidelobes that can be useful some times….
I do not have any fancy formulas or even real world ground gain experience, but I read a lot and figure things out. I suspect that both Leif’s formulas and Peters experience can be reconciled. For the low yagi near flat land, it seems obvious that distinct lobes will be present for various yagi heights and Leifs assesment makes perfect sense even though I do not FULLY understand it. What also seems logical to me is that an array with a very narrow vertical beamwidth looking way out on to a lake will have many splinter sized lobes due the great number of wavelengths distant to the reflection point. These lobes, logically would tend to converge so there is effectively no difference with polarization. Since water is a great reflector, the brester effect is no factor for vertical polarization. Both Leif and Peter makes perfect sense. Hey Leif, what happens to 45 degree polarization signals? Is the peak between vertical and horizontal? Peter, I wonder how high your array is and how far the lakes edge is from your array?
For Mikes 4 yagi example, I think since the upper two yagis are at a very different height compared to the lower two yagis, the resulting maximum lobe is very different for the two sets, so there is never a chance for the two lobes to converge. I suspect that very high 4 yagi arrays can show ground gain, but with very narrow elevation lobes.
I’ll be QRT now in search of a country home on the west side of a lake.
Jim, to answer your questions:
The bottom two antennas of my 6 stack are 5 mtrs over ground and the top two are at 14 mtrs. Distance to the lake is about 200 mtrs. I wish everyone could have a moonset or moonrise lake..
My secret is that I go out there and salt the water before every moon session.. :-))
Having heard that using vertical polarization results in reduced ground gain, I would be interested in hearing comments from those of you that can switch your polarization between v&h.
I just put up a small 6m eme array: http://www.mtaonline.net/~nl7z/6m%20eme.html
The reason for the vertical polarization is to reduce the spurs I get from local tv ch2.
I have compared horizontal vs vertical echoes on 144 MHz when ground gain has been present hundreds of times and I could never see any difference. Both polarities have been enhanced equally. I know that some will air different opinions, but on this I am very sure. My setup is 6 x 19el xpol v/h. Same thing when I was using my 8 mtr dish and a rotable feed for 144 MHz.
Hi Peter and Kevin,
I have studied the ground gain on 144 MHz and found that it is similar for V and H polarisation. Ground gain does (of course) not occur simultaneously on H and V, when one has a maximum, the other has a minimum. Using the correct polarisation while the moon is rising makes a very large difference 🙂 (I am sure Peter can see the difference time-wise. When one polarisation has ground loss so it nearly disappears, the other polarisation is strong.)
If V pol helps against QRM I think it is a good idea to make use of that. Maybe it will be clever to mount the antenna nearer to ground to make the ground gain last longer while loosing the second lobe. Guess it depends on the local ground properties.
On 17-Sep-2004 SM2CEW wrote:
Leif, we have been over this before, ground gain IS present at the same time in both polarities, absolutely so!
And since it was up for debate I have been checking even more closely, and the ground gain pattern is exactly the same for both vertical and horizontal over time, or call it moon position over the horizon.
I suspect that may be due to the polarity rarely being all one way or the other, but some of both almost all the time, as Lionel has observed over the years with his rotatable (not switched) array.
Just a thought.
To be sure about what is going on one has to check the reflections during many moon-rises and moon-sets. I have been doing so and waited for the rare occasions when a transmitted H-pol signal comes back in pure horisontal polarisation. (Then a transmitted V-pol comes back vertical as one should expect.) My two-channel system measures polarisation angle accurately so I know when Faraday rotation is right for the experiment. The difference in echo levels between H and V is absolutely remarkable beyond any doubt, well above 10 dB at the point of maximum ground gain for one and maximum ground loss for the other.
There are of course points in between when the ground reflection arrives at a phase angle of 90 degrees. Then there is similar (but modest) amounts of ground gain both for H and V.
I do not know what is behind Peters observations, I doubt they were done during times with zero Faraday rotation.
So if there is a difference between Leifs an my findings they are certainly not because of me making observations only at Faraday offset greater than zero as implied below. And since this was up for debate a few years ago on moon-net I have made it a point to check this very closely.
Could the different vertical pattern between his single yagi/4 yagi and my 6 yagi (3 high stack) play a role? My ground gain (over a lake) sets in at very low elevation, 3deg or less.
Hi fellow hams, please allow me to add a side note on this ground gain issue.
I hear what EME operators say about ground gain but I still have some stomach-ache with this concept. If ground gain is effective in EME, it has to be effective in, say Aurora, MS and sporadic E dx propagation too, i.e. in all dx modes associated with nonzero elevation angles. I am actually surprised that this effect isn’t considered in terrestrial dx propagation at all. Perhaps the effect isn’t that obvious here compared to EME operations, nevertheless a consistent picture would be highly desirable.
I appreciate your discussion very much indeed. Learning and understanding ground gain in EME operations, we may possibly draw conclusions from it with respect to double-hop sporadic E propagation. Contrary to the EME community, ground reflection of 2m radiowaves isn’t generally accepted in the terrestrial dx community – and we indeed found potential examples of ground reflection in forward scatter which are difficult to explain and difficult to accept.
Ground reflection in the near field is well documented in the antenna literature and should not be controversial except, perhaps, for the reflection characteristics of actual (non-perfect) ground in real-world (generally cluttered) locations. Those are notoriously difficult to measure, ergo some of the thread we’ve been seeing on moon-net. Double-hop sporadic-E raises a separate issue, namely ground reflection at long distances from the transmitting station. That is one possible mechanism for the long-distance propagation that has been observed, but there are others, such as chordal hop from one Es cloud to another, that could also explain it.
I don’t have a good explanation for the long-distance Es, but I have had a lot of experience with near-field ground reflection in EME and have no doubt at all of its existence at my QTH.
As for long-distance Es, I made one QSO, many years ago, with K0WLU/7 at a distance of 2585 km (1605 mi), at a time when I was also hearing Es signals from W8 stations approximately halfway between us. That would suggest double-hop Es, but of course does not prove it.
Here are some practical examples that the grond gain effect isn’t only noticeable in EME communications. I measured from echoing that the ground gain effect max. when the Moon is at 10 degrees elevation at my qth. At the other hand from my logs the most meteor scatter qso’s are made around 1000Km. At this distance the reflection area is about 10 degrees elevation seen from my qth. Coincidence? Also in satellite transponder communication the effect noticeable.
HI VOLKER, All EMErs as well as DXers
First of all – I am NOPT an expert as well but : Its my general observation through mni Yrs, that has brought me to this conclusionabout the point ground reflection gaian, and why its NOT is being useble for other reflections
Lets make a throught-experiment.
When the signal is being reflected from a object (moon) at a low angle you must imagine standing and looking a night – looking at the moon. You will see the direct moonlight and the reflected . from the ground ( play its water to see this.
This is what happens – and the “gain occur” when the phases of the two sources is correct. Seen from this point, it should be rather easy to understand the “gain” now and then. Now At Au the Freq is changing fast and simultainsly so YOU will NOT see a phaseaddition of gain here.the
This will eigher not be actual at reflections at higher angles why the phasedifferance will be too large.
This is my understanding of the phenomen .
From a mathematical point of view, the elevation angle of maximum and minimum ground gain depends on the actual terrain slope and, of course, on the actual antenna height above ground. Thus, changing the actual antenna height you may convert a field strength minimum into a maximum. With other words: with variable antenna height, you may permanently operate at maximum ground gain in all EME QSOs.
In accordance to a brief calculation on my blackboard, you must double the antenna height in order to convert the first minimum into the first maximum. For example: if your actual antenna height is, say 7 meters above ground and your EME QSO is suffering from the first field strength minimum, push your array up to 14 meters and this minimum converts into a ground gain maximum. Another example: assuming your antenna height is 18 meters and you are entering the third null at high elevation, you may do the following:
i) to address the third ground gain maximum: increase your actual antenna height to 120 percent of the original height, i.e. 21.6m ii) to address the second ground gain maximum: reduce your actual antenna height to 80 percent of the original height, i.e. 14.4m iii) to address the first ground gain maximum: reduce your actual antenna height to 40 percent of the original height, i.e. 7.2 m
Thus, we may identify various optimum antenna heights as a function of the actual moon elevation. This will involve some sort of mechanical engineering, of course, but permanently operating at optimum ground gain in all EME QSOs appears quite an attractive opportunity. In my view, this method may in particular boost the EME capability of small arrays – compared to the big guns in moonbounce communication, the mechanical effort is much smaller here.
On 20-Sep-2004 I3DLI wrote:
Volker: From a practical standpoint, you are dreaming. Believe me.
> Having heard that using vertical polarization results in reduced ground
> gain, I would be interested in hearing comments from those of you that can
> switch your polarization between v&h.
The reason it is explained in my article on ground gain on www.oz1rh.com Pls read the original text as the table is not displayed correct in this email.
For DX-ers on HF it is well known that the radiation angle of a horizontal polarized beam is a function of its height over the ground and ground conductivity has little influence on low angle of radiation. Things are different for vertical polarization. A vertical antenna needs perfect ground to give low angle of radiation. In fact is does not radiate at all below an angle called the Brewster angle. This angle is dependent of the conductivity of the reflecting ground. Check an antenna book on verticals for 80 m, the 80 m DX’ers know all about this. Does low angle of radiation interest us for VHF? Yes ground gain is happening in the range of 0-10 degrees.
|Horizontal polarization||Vertical polarization|
|Ground gain for one reflection||5-6 dB||Perhaps 3 dB|
|Ground conductivity||Little influence at low angles||No radiation below Brewster angle 5-20 degrees|
|Lossy ground||Little less ground gain and not so deep nulls in pattern||High Brewster angle 20 degrees?|
|Good ground conductivity (salt water)||Deep nulls in pattern, but peak almost uninfluenced||Low Brewster angle < 5 degrees?|
It seems a good idea to use horizontal polarization if one wants low angle of radiation. Vertical polarization has less ground gain. A circular polarized signal contains two components: a horizontal polarized and a vertical polarized one. Ground reflection influence the two components differently as describes above and after ground reflection the signal is no longer circular but somewhat elliptical polarized at low radiation angles.
Having a wind-up tower, I’ve tried this on 144, and it works. But fitting an electrically operated winch and height readout is (like 144!) a long way down my list of EME priorities…
Of course we can also make use of ground-gain effectively for long periods without varying the height of the antenna, if we have suitable local topographies. Having a small ridge which rises from the south-east to the south of my house, I can enjoy ground gain, and surprisingly frequent audible echoes with my single (h-pol) yagi, for several hours at low southern declinations. The single biggest EME signal I’ve ever heard on 144 was from a VK running 400W and 4 (v-pol) yagis, when we were both able to exploit ground gain. It’s a pity that there aren’t more people active at those times.
Hi Peter, Ray and all,
> Could the different vertical pattern between his single yagi/4
> yagi and my 6 > yagi (3 high stack) play a role? My ground gain (over a lake)
> sets in at very low elevation, 3deg or less.
Confronted with the details of what Peter has been doing I decided to have a look in a text-book. Yes, ground reflections may behave differently and it depends on the angle and the properties of the reflecting surface. There is something called the Brewster angle. I think it is about 8 degrees for water but I do not know for sure. In a loss-less dielectric there is no reflection at all for vertical polarisation. The reflection changes sign at the zero-crossing. I must conclude that sweet water is not very lossy (compared to the high dielectric constant) and therefore Peter observes the same phase in his ground reflections from both H and V.
Over farm-land and at higher elevations the phase is opposite between H and V ground reflections. According to my book, lossy media may give any phase shift near the Brewster angle and a wave that comes in with linear polarisation may arrive as an elliptic wave at the antenna. I have never observed it, seems I have good conducting ground around here:-)
I guess others on this list know it all much better. One could compute it with NEC or look in a better text-book than the one I have. I tried to search the Internet but found nothing. It would be nice if someone could compute and upload the theoritical reflectivity and phase shift for reflections on salt and sweet water as well as some types of land.
To All of intrest All having been said. I worked NL7Z on 6 EME with his vertical pol, he showed a pronounced peak at 4 deg, nothing was heard from 0-3.5 degrees, others are in the process of scheds with him . I think he will do well with this setup, the only reason for his vertical polarity was to reduce the local spurs from a horizontal TV TX on his receive . Don’t knock success
Hello Chris and all I would like to point out that as we try to lower the take off angle by increasing it’s height we also introduce a larger field of local noise. The closer we can keep the eme array to the ground the quieter it will be , of course this is the norm, there is always someone somewhere that this will not be true. The most we can get is about 6 dB and you are still limited to the relative short window at the horizon. With the expense of tall towers, long low loss feedlines and control cables, preamps out of reach, extra windload at these heights, hard work to get to them, etc, etc, just place it at a good low level and work them all, just put up 4 or more medium size horizontal antennas and enjoy the whole sky. Make it simple , if it is down near the ground you don’t even need motor drives, It was several years before I installed motors on my array and I worked all 50 before then. once each half hour just reset it and enjoy.. On 50 and 144 never use any polarity control other than patience and next time maybe…… I’ll get off my soap box now. just enjoy this great hobby
On 21-Sep-2004 AL7EB wrote:
I use four M2-xpol-20 antennas on 2m and normally run V-pol to the lower-48 states as spacial polarity shift dictates. I have run both polarities with smaller stations in Europe at my Moon-rise (their Moon-set) and see slight enhancement from 4-7 degrees. Of course Faraday can influence polarity choice a lot. There seems to be so many variables that can affect signal level that it is hard to make any hard fast statements. I do find myself in V-pol a lot, though.
Boy you all read things close, I had to go back and reread what I had written to find this one… “on 50 and 144 never use any vertical pol” Now that is a good one , Sorry, what I was trying to say, was that I have never used polarity control on 50 and 144, sometimes it would have been nice I guess. but with 5 EME stations under one roof I try to make things simple. I am for anything that works, Just be active and enjoy this great hobby of ours.
During WWII the Germans used ground reflections and variable antenna height to measure the angle to enemy aircrafts – around 220 MHz I think.
Some hams use variable antenna height to get ground gain at the desired moon angle. According to what I have been told the theory described on www.oz1rh.com works in practise though my theory (which I did not invent but gathered from the referenced sources) may not be complete. I know my text on vertical polarisation is short, but I still think ground gain from vertical polarisation needs good ground conductivity and that it will not go below the Brewster angle – which is low (>1 deg?) over good ground = salt water and several degrees (5-10?) if ground conductivity is bad.
I guess I should have commented on the fact my antennas have to look at a +2 degree slope to the east at Moon-rise and thru a mixed forest of 45-foot birch, spruce, and cottonwood which fortunately do not totally attenuate the signal (leaves drop by late Sept. helping). This conspires to limit my lower elevation limit probably due as much to ground noise as any other effect. I find I don’t begin to hear until the Moon rises over 2.5 degrees.
One factor in the raising of the tower from 40 to 50 feet (to clear most of the trees at Moon-rise). The other was deterioration of the concrete tower base which required replacement (used better materials this time and used self-supporting base). The spring storm (65 mph wind sustained for 30-hours) of 2003 killed my azimuth rotator and put me out of business until last winter (then discovered the elevation did not work too late into winter to fix). So taking the opportunity to re-build better including burial of all feed and new control lines in pvc conduits…looking forward to Oct. 9-10!
Long time since it was so good reading here!
One question! how far from antenna does the ground affect the pattern? (i hope i used the right word) i guess it have with the elevation angle to do and also antenna height.
Peter, Leif, Palle, et al. —
Wave reflections from the ground or any other surface involve a “reflection coefficient” with both magnitude and phase. For real surfaces the magnitude of the reflected wave (relative to the incident wave) is less than 1.0. The phase shift depends on polarization and on the angle of incidence.
For ground reflections, horizontal polarization leads to a reflection magnitude close to 1 and a phase shift of nearly 180 degrees. Everything is relatively simple, and the expected elevations of maxima and minima in your antenna pattern depend only on antenna height.
For vertical polarization, things are different. Both magnitude and phase of the reflected wave depend strongly on the wave angle. The phase shift will be close to 180 deg at low elevations, decreasing to near zero at high elevations. The “Brewster angle” that Palle mentions is where the excess phase of the reflected wave goes through 90 degrees, and the magnitude goes through a minimum. As Palle says, at radio frequencies the Brewster angle is < 1 deg over salt water, about 5 deg over fresh water, and around 15 deg over average ground.
The upshot is that at elevations *below* the Brewster angle, vertical and horizontal polarizations behave similarly with respect to the “ground gain” that we are discussing. Because the magnitude of the reflection coefficient is smaller for vertical polarization, the pattern maxima and minima will be less pronounced; but the elevation angles of extrema will be nearly the same. At elevations *above* the Brewster angle, situation is reversed: maxima in the Vpol pattern will coincide with minima in the Hpol pattern.
Peter says “My ground gain (over a lake) sets in at very low elevation, 3 deg or less.” His Brewster angle is presumably that for fresh water, about 5 degrees, so Peter’s conclusion makes sense. Over a perfectly flat lake, large in extent, I would expect his Hpol ground gain to be close to 6 dB and his Vpol ground gain to be more like 4 dB, but the 2 dB difference would be hard to measure. Moreover, “real” conditions (a somewhat smaller lake having surface waves, etc., etc.) would probably reduce this difference.
If Peter did the same experiments looking over salt water, where the Brewster angle is < 1 deg, he would reach the opposite conclusion. Vpol maxima would then occur at the same elevations as the Hpol minima.
Those of us with antennas looking over normal ground, rather than water, will nearly always see our ground gain below the Brewster angle. We will therefore get slightly (~1 or 2 dB) less ground gain with Vpol than with Hpol; but we should always see the pattern maxima at the same elevations, regardless of polarization.
Hakan asked “how far from antenna does the ground affect the pattern?” I believe the correct scale is that of the first Fresnel zone. Figure on a few hundred wavelengths, at least — and more if your antenna is higher, and the ground-gain lobes therefore lower.
Joe and all!
I have wrote down a date where i found realley strong signals from VK7MO, is it possible to calculate what should be a normal signal level? i decoded him on -14db in JT65B and degradation was 2,7db.
For VK7MO I used P=400 W, Tx feedline loss = 1 dB, antenna gain 20 dBi. For your station I used NF=1 dB, Antenna gain = 22 dBi, ground gain 4 dB, and total sky temperature 700 K. These numbers produced an estimated signal strength of -14.3 dB in WSJT units, just about what you observed.
As everyone on Moon-Net knows, it won’t always work out this nicely. Many things affect signal strength at a particular time, and it is *very* hard to predict all of them to within +/- a few dB.
I think what Joe states below applies to the typical high yagi, perhaps 20 or 30 meters high. In that situation in an Urban area, you would almost certainly have a house nearby that would break up the reflection. I never see ground gain on my 30 meter high yagi.
An interesting situation can happen even on a small Urban lot when the yagi height is limited to only a few meters. The yagi is much closer to the ground, so the reflection point is much closer to the yagi and the fresnel zone is much smaller at the reflection point. I think you could use some simple geometry to figure out about where the reflection point is. When the yagi is this close to the ground, the peak elevation for maximum ground gain can be in the 10 to 15 degree range. If you draw a line from the yagi toward the ground at the same angle as your elevation lobe, you should be very near the mid point of the reflecting ground. Some sources of inaccuracy would result from where exactly on the yagi you drew your line from as well as not accounting for the need of an additional 180 degree phase shift on the reflection path to bring the reflected signal into phase with the direct signal. I do not have any math to back this up, but practical experience suggest that my statement must be fairly good aproximation. Perhaps someone else has better math that can get closer. I did some experiments when my horizontal array was down for upgrade.
When only a 4 element yagi is used, the yagi can be placed very close to the ground (perhaps 1 meter) and it is easy to see that the reflection point must be very close in to the yagi. One important consideration is that if a very long yagi is placed too low, the ground gain lobe will want to be too high and both the direct and reflected signal will be well outside of the main lobe of the yagi. Remember, the direct ray is happening at the maximum signal elevation angle in a positive direction as well as a reflected ray at the same negative elevation angle. The yagi must be placed high enough that the direct and reflected component of the signal is within the -1db point of the free space elevation pattern of the yagi. This would give maximum moon time with good gain for any specific yagi. This would be a major concern for a 100 foot boom yagi and would tend to suggest better luck with 4 or more 3wl horizontal yagis side by side only a few meters off the ground. During moon-rise one might start out with the array a bit higher off the ground to get an early start on moon-rise, then slowly lower the array as the moon rises to track the moon elevation. When the array is too low, gain falls off because the rays are outside of the beamwidth of the yagi. This might work surprisingly well even at somewhat higher moon elevations because with 4 x 3wl yagis there would be signal to spare even with modest ground gain. Since the yagis are operated so close to the ground, they can be maximum gain designs without suffering from too much local noise pickup.
This is something I would consider when I get my large antenna farm. Perhaps 16, 3wl yagis would be managable with a W5UN type mechanical design 50 meters wide and 2 – 3 meters high. Perhaps this can be done with standard field irrigation hardware if variable elevation was not an objective. Hmmmm, 13dbd gain for 3wl yagi, 12db stacking gain and 5 db ground gain….. 30dbd!
OZ1RH published in the Prague EME conf proceedings page 99, the formulae which enable you to calculate the position and dimensions of the elliptical Fresnel zone, where the reflection takes place. I calculated the numbers for a horizontal( 0 degrees elevation )144MHz antenna height of 20 m . The results are. distance to the reflection point 800m distance to the nearest point of the Fresnel zone 136m distance to the furthest edge 1,043m max width of the fresnel zone 113m Quite a substantial area, to get full effect one would need this to be flat to (I suspect) a few wavelengths. At higher elevation angles the zone will be further away. Another factor is slope of the ground accross the reflection zone. I can assure you, from work done in the MLS programme in the 1970s, that a uniform cross slope accross the fresnel zone will introduce a azimuth pointing error, so if you have that condition it is probably worthwhile exploring the azimuth direction for best results.
On 22-Sep-2004 GM4JJJ wrote:
Been following the interesting discussions on reflections and Brewster angle, the same type of effects are visible to us with our eyes and Polaroid sunglasses:
When light reflects from a horizontal surface at an angle, the reflected light tends to be polarised horizontally. At a specific angle, the light is completely horizontally polarised because any vertically polarised light that hits the surface at this angle is allowed to enter the surface without reflection. Since reflections from horizontal surfaces are mostly horizontally polarised, glare is mostly horizontally polarised. Polaroid sunglasses are designed to filter out the horizontally polarised light partially eliminating the reflections.Read More
This is an example of a real QSO made by EA6VQ that could help understand beginners the right procedure for answering a station who is calling CQ via the Moon. (Please notice that the values of date, time, azimuth, elevation, etc. shown are not the real values but the values when I recreated the QSO from the WAV files in order to make this page)
In this case I knew in advance from the DX-News page that S79HP EME expedition was going to operate on 144.144 MHz, always transmitting the first period (even minutes), so I:
- Tuned the transceiver to that frequency
- Entered his callsign and grid in the corresponding input boxes
- Unchecked the “Tx first” box (as I had to TX second this time)
- Pressed the “Gen Std Msgs” to generate the messages and have them ready to transmit.
- Pressed also the “Monitor” button, and waited for some signal.
After some time I began to see a signal in the “SpecJT” window.
When the one-minute period was over, WSJT easily decoded the CQ call of S79HP. So I:
- Clicked with the mouse on the red spike (that corresponds to the frequency of the JT65B Sync tone) and checked the “Freeze” box. With this simple actions I told the program that I wanted it to concentrate on decoding signals which Sync tone was right on that frequency.
- Decreased the value of “Tol” to 50 (50 Hz). This is like setting a passband filter of that width, so the program will not take care of other Sync signals, even although you still could see them in the SpecJT window.
- Made sure that I had “Text 1” selected, that is the right text to send when answering a CQ
- Set the “Auto” to ON, so that the program would initiate the TX and RX sequencing automatically.
Then, the program shown the new decode…and “bingo”, S79HP had received me and it was sending me the O report (“OOO”). I selected the “Text 3” (RO) to confirm him I had received his “O” report and at the same time send him an “O” report as well. (Please notice that in EME it’s not meaningful to use the RST report because the signals are almost always too weak, so the normal is to exchange an “O” report, meaning that both stations are capable of copying each other.)
WSJT transmitted my “RO” message and then passed to RX again. This time I could see the following in SpecJT.
And when the program decoded it I could see that S79HP had sent “RRR” that is the message confirming he had received my “RO” and so at this point the QSO was complete (An EME QSO is considered complete when one of the stations receives the “RRR”, not before). I selected the “Text 5” (73) as a final courtesy message. Although sending/receiving “73” is not required to consider the QSO as complete but it’s a common practice to send it once, after having received the “RRR” from the partner station.
Sent the 73 message for only one period and selected “Auto” to OFF in order not to transmit any more on his frequency..
Easy, isn’t it?Read More
There is still some confusion about Moon Bounce operation and the station requirements for making a QSO in the VHF bands using the Moon as a reflector. Might be you have read in the past that only very large stations with four antenna arrays and Kw amplifiers (and skilled CW operators) were capable of working via EME (Earth-Moon-Earth). This was true till 2002, but nowadays thanks to the JT65B digital mode provided by the WSJT program, any station having an 2m. SSB transceiver capable of delivering 50 W and a directional antenna can make successful contacts via EME. And furthermore, no CW knowledge is required!
But, I can’t elevate the antenna to track the moon…
In order to make an EME QSO, the most important requirement is (obviously) that both stations can see the Moon simultaneously (what is called “to have a common window”). If you have a typical tropo/MS antenna you are likely not to be capable of elevating it, but YOU STILL CAN make EME contacts when the moon is near the horizon.
A single Yagi antenna pointing to the horizon normally allows to work EME till the Moon is up to 15 or 18 degrees above the horizon. If you have a clear take off towards your moonrise/moonset this means about 90+90 minutes (3 hours) of possible operation every day!
Do I need a good preamplifier?
A preamplifier with a low noise figure, mounted as close to the antenna as possible is always a very good help, but it’s not strictly necessary to make your first contacts. The larger EME stations are normally using a lot of power and somehow this will compensate your little reception. You can always get a preamplifier later, when you decide it’s time to improve your reception.
You are only 7 steps away from making your first MoonBounce QSO! Keep reading…
Step 1. Get the WSJT free program
WSJT is a digital communications program written by K1JT and specially intended for weak signal communications in the VHF&up bands. It provides different modes adapted to different modes of propagation and bands. For 2m MoonBounce you will use the JT65B mode. You can download it from K1JT’s WEB site.
Once you have downloaded the setup program you will have to install it your PC. If you are familiar with installing Windows applications this will be very easy, as you simply have to accept the default options offered by the setup program, however if you want you can also have a look at the WSJT setup procedure.
Step 2. Connect the PC to the radio.
If you have already worked some kind of digital communications (RTTY, Packet, PSK-31,etc) you will possibly be able to use the same interface for the WSJT program, and you could skip this step.
If you have never connected your PC to the transceiver then you will need some kind of interface to connect them. If you can afford it the best is to buy a commercial interface, such as the RigBlaster (available at West Mountain Radio).
If you want to build your own interface, you will need to make the serial port cable from your computer be able to key the PTT line of your transmitter. You also must isolate and attenuate the audio from the computer sound card (Line output / Speaker), so it can be connected to the transmitter MIC input. Information on how to do this can be found in many places, but here you have two simple designs.
And finally, you will have to split the audio output from your receiver, and run an audio line over to your computer sound card (Line input / Mic). This will permit your computer to also hear your receiver, and process the signals coming in.
Step 3. Automatically synchronize the PC Time.
WSJT modes (and specially the JT65x) require of a very accurate PC time in order to achieve good results. So accurate that in fact it’s not enough to update the PC time manually. It’s necessary to update it automatically according to some reliable source.
The most common way to do it is through Internet by using a Time Synchronization program, such as Dimension 4 or Automachron, and configuring them to synchronize the time every 5 minutes or so.
It is important that you select one of the time servers that will provide accurate and reliable time corrections to your computer from your particular location and internet connection. You can verify that the time has been properly set within a half second, by listening to WWV and watching the seconds display on the Dimension 4 program screen. If the time server you select doesn’t seem to match WWV, or there seem to be corrections >.1 second when you repeatedly manually set the time with Dimension 4 or Automachron, try selecting a different time server from the optional list provided.
However, if you don’t have an Internet connection in your radio shack then you still have other alternatives to achieve an accurate PC time synchronization:
se the time signals broadcasted in LW and MW and a program like Radio Clock that keeps the PC time synchronized simply connecting the speaker output of the receiver to the line input of the PC sound card.
Use a GPS receiver connected to the PC and the free GPS Utility program to update the PC time with the GPS time.
Step 4. Run WSJT for the first time and Configure it
Configuring the WSJT options properly is important in order to make successful QSO, so please read carefully the page on configuration.
Step 5. Rig setup
Make sure your transmitter is set to USB position and that the receiver is set to the widest filter width. If you have bandpass adjustment on your receiver, make sure it is set to pass tones from 1200 Hz – 1800 Hz (usually by turning the bandpass off). In general you could leave the noise blanker active, but make sure you turn the AGC off. If your rig has a Mic. compressor or speech. processor button you should also activate it, to insure that you are sending each of the tones at full power.
Step 6. Program operation
You should definitively read the operating manual provided with the program as it covers almost all details you need to know, however you could also find interesting to watch the following visual examples of real JT65B EME QSO.
Get on the air
Now you are ready for your first WSJT EME QSO. However here there are some additional suggestions for you:
- Always make your first attempts arranging a “sked” with some of the bigger stations (8 Yagis or more). Please contact me and I will be pleased to calculate the most favourable date and time for trying a 2m EME QSO with you.
- Scanning the band looking for signals is not a very good idea. Only stations with large arrays can detect the weak EME signals by ear. You had better look for the frequency of the stations calling CQ, in the DX-Cluster or in the JT65 EME chat or in the ON4KST EME chat,. Then you can try to detect their signal and answer to their CQ.
- Don’t expect to hear the signals on the speaker or headphones. Although you could eventually listen to the signals of the most powerful stations, that won’t be the rule in JT65B EME operation. You should pay attention to the SpecJT waterfall display and you will see signals that are too weak to be heard by the human ear, but that could be neatly decoded by the program.
- Don’t give up if you don’t succeed in you first EME attempts. There are many factors affecting the Earth-Moon-Earth path and some of them are unpredictable. Often you will have to try several times till succeeding in a QSO.
- Don’t give up if you don’t get an answer in the first minutes. EME conditions change very quickly, mainly due to polarization changes, and quite often you will need up to 30 minutes to complete a QSO. Continue transmitting all you periods so that your partner station will have to chance to copy you when signal improves.
- Don’t get obsessed trying to detect your own echo off the Moon. If you have a single Yagi and a few hundred watts it would be really surprising that you could detect them. Even when you can’t detect your own signal after the reflection off the moon many other stations with larger antennas will be able to detect it, and that is the really important thing in order to achieve a QSO.