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#1
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On Wed, 09 Feb 2005 17:52:37 GMT, "John" wrote:
Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? Hi John Use a propagation modeler and tailor the antenna characteristics to observe the results. 73's Richard Clark, KB7QHC |
#2
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Angle of Radiation
Can someone tell me please an easy way to calculate the optimum angle of
radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues as to how to work this out. Thanks John |
#3
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Maybe check ON4UN's book -- "Low Band DXing"
He has info on this Too lengthy to quote here -- Caveat Lector (Reader Beware) Help The New Hams Someone Helped You Or did You Forget That ? "John" wrote in message ... Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues as to how to work this out. Thanks John |
#4
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Get W6ELProp - it's easy to use, and free. http://www.qsl.net/w6elprop/.
Roy Lewallen, W7EL John wrote: Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues as to how to work this out. Thanks John |
#5
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The elevation angle of a radio wave is not related to antenna construction.
It is calculated by trigonometry and is geometrically related to the distance between two points on the Earth's surface, the height of the ionospheric reflecting layers involved, and the number of hops. If a radio wave leaves the Earth at one end of the path and returns to Earth at the other end, then the elevation angles of the path taken are the same at both ends. And the same in the other direction. (To forestall nitpickers let it be said things can vary around averages.) The optimum angle at which to point a radio antenna, either for transmit or receive, is obviously the same as the elevation angle of the radio path. BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE OF THE RADIO PATH. For given points on the Earth's surface, height of reflecting layer, and number of hops, the angle of elevation of the radio path is fixed. The angle at which the radiation from an antenna is a maximum is an entirely different matter. Calculation of a path elevation angle on a curved Earth not very difficult but is a little too complicated to be written here. Up to 1500 groundpath miles the Earth can be considered to be flat. Trig calculation is then schoolkids stuff. Full formulae can be found in maths books under "Spherical Trigonometry" or in practical radio engineering books. Calculations can be interesting but are invariably roughly approximate because layer height involves guesswork. And by the time you've finished a calculation the height has shifted. Or the number of hops has changed from 2 to 3. The only things which remain static are your own latitude and longitude. To calculate propagation statistics of one and two hop radio paths, including elevation angles, download simple program TWOHOPS in a few seconds from website below and run immediately. ---- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
#6
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On Wed, 9 Feb 2005 20:35:14 +0000 (UTC), "Reg Edwards"
wrote: The elevation angle of a radio wave is not related to antenna construction. It is calculated by trigonometry and is geometrically related to the distance between two points on the Earth's surface, the height of the ionospheric reflecting layers involved, and the number of hops. If a radio wave leaves the Earth at one end of the path and returns to Earth at the other end, then the elevation angles of the path taken are the same at both ends. And the same in the other direction. (To forestall nitpickers let it be said things can vary around averages.) The optimum angle at which to point a radio antenna, either for transmit or receive, is obviously the same as the elevation angle of the radio path. BUT NO AMOUNT OF WAVING THE ANTENNA ABOUT WILL AFFECT THE ELEVATION ANGLE OF THE RADIO PATH. For given points on the Earth's surface, height of reflecting layer, and number of hops, the angle of elevation of the radio path is fixed. The angle at which the radiation from an antenna is a maximum is an entirely different matter. Calculation of a path elevation angle on a curved Earth not very difficult but is a little too complicated to be written here. Up to 1500 groundpath miles the Earth can be considered to be flat. Trig calculation is then schoolkids stuff. Full formulae can be found in maths books under "Spherical Trigonometry" or in practical radio engineering books. Calculations can be interesting but are invariably roughly approximate because layer height involves guesswork. And by the time you've finished a calculation the height has shifted. Or the number of hops has changed from 2 to 3. The only things which remain static are your own latitude and longitude. To calculate propagation statistics of one and two hop radio paths, including elevation angles, download simple program TWOHOPS in a few seconds from website below and run immediately. The original poster, John, had already indicated the answer to his own question - but Reg was the only one who recognized that and had the correct follow up. Congrats, Reg. Bob, W9DMK, Dahlgren, VA Replace "nobody" with my callsign for e-mail http://www.qsl.net/w9dmk http://zaffora/f2o.org/W9DMK/W9dmk.html |
#7
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John wrote:
Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues as to how to work this out. Try the propagation chapter in the ARRL Antenna Book. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
#8
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Cecil Moore wrote:
John wrote: Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues to how to work this out. Try the propagation chapter in the ARRL Antenna Book. That would be a very good introduction to modern software like W6ELPROP. What it teaches you is that angles of arrival vary considerably, even for one given path, for reasons ranging from time of day to time in the 11/22-year sunspot cycle. Remember that the F-layer is constantly changing height, especially if it's around around dawn and dusk at one of the reflection points. This means that at certain times the propagation has to 'flip' from say 3-hop-F to 4-hop-F, so the angle will flip too. And don't forget the E-layer, if that's there too. W6ELPROP will actually tell you what propagation modes are the most likely at various times of day... and the reality is *much* more complicated than the simple pictures shown in older books. The ARRL Antenna Book does rather assume that you can put up any antenna you can dream of; in which case, it will help you design the optimum system. Ideally, the antenna needs to be able to adapt to the needs of the moment. But for most of us, it's much simpler than that. We can never achieve the low angles that are sometimes needed for some of the most important paths, so it simply comes down to doing the best we can. "Adaptability" comes down to possibly having a second-choice antenna... which at certain times may turn out to be better. But even if we can't actually *do* anything about it, it's better at least to understand that arrival angles (or conversely, optimum launch angles) are actually very variable. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
#9
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Looking at the ARRL Antenna book it seems that the angle of radiation is
pretty well fixed on the type of antenna. "Ian White G3SEK" wrote in message ... Cecil Moore wrote: John wrote: Can someone tell me please an easy way to calculate the optimum angle of radiation from a transmitting antenna over a given path on the HF bands (160m - 10m)? OK, I guess its all to do with the height of the reflective layer in play and the distance of the QSO but I'd really appreciate some clues to how to work this out. Try the propagation chapter in the ARRL Antenna Book. That would be a very good introduction to modern software like W6ELPROP. What it teaches you is that angles of arrival vary considerably, even for one given path, for reasons ranging from time of day to time in the 11/22-year sunspot cycle. Remember that the F-layer is constantly changing height, especially if it's around around dawn and dusk at one of the reflection points. This means that at certain times the propagation has to 'flip' from say 3-hop-F to 4-hop-F, so the angle will flip too. And don't forget the E-layer, if that's there too. W6ELPROP will actually tell you what propagation modes are the most likely at various times of day... and the reality is *much* more complicated than the simple pictures shown in older books. The ARRL Antenna Book does rather assume that you can put up any antenna you can dream of; in which case, it will help you design the optimum system. Ideally, the antenna needs to be able to adapt to the needs of the moment. But for most of us, it's much simpler than that. We can never achieve the low angles that are sometimes needed for some of the most important paths, so it simply comes down to doing the best we can. "Adaptability" comes down to possibly having a second-choice antenna... which at certain times may turn out to be better. But even if we can't actually *do* anything about it, it's better at least to understand that arrival angles (or conversely, optimum launch angles) are actually very variable. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
#10
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Mike Coombes wrote:
Looking at the ARRL Antenna book it seems that the angle of radiation is pretty well fixed on the type of antenna. Talking about "the" angle (as if there was only one) is misleading ourselves. Every antenna has a *range* of angles over which it radiates (or receives) the best. The aim is to make that coincide with the *range* of angles over which signals are likely to arrive. This is made very clear in the 18th edition of the Antenna Handbook onwards. It presents arrival angles as a statistical range of probabilities, over a spread of possible propagation conditions. If you have only one antenna, then obviously you try to make its very best radiation angle coincide with the most *likely* angle of arrival. But it's a game of chance. Occasionally the angle may be very different from the most likely value, so you have to accept that you're going to be some dB down... or dead in the water. And that is where having a choice of different antennas really scores. -- 73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.co.uk/g3sek |
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