The thing that I was trying to convey with the measurements we made was
that the TH7DX tribanders are not critical in f/b vs frequency in contrast
to what someone suggested.
What the precise f/b numbers are is another interesting topic, as is the
precise gain of an antenna. Hovever, operating on the bands and using the
antenna under various different conditions will soon tell if it is a
performer, omnidirectional or a dummyload..
And in my opinion, given the tests we have conducted over the years, ground
wave tests over 30 km flat land gives a fair _indication_ of what the f/b
is, good or poor.
This has also proven to be the case with various VHF/UHF yagis that I have
built and used on terrestrial and EME operation. On VHF. terrestrial
contest operations ground wave signals (stations locally, nearby) are
really what you want to attenuate because locals create QRM in your
receiver. (wideband noise/hash/clicks etc)
So f/b on groundwave is important and so far, from what I have seen the
results are pretty close to what the software model tells you. But again,
in precise numbers you can't say it is exactly -19db or -21db but you can
sure tell -8db from -18 db.
At 01:07 2004-06-26 , you wrote:
>At 08:51 PM 6/25/2004, Tom Rauch wrote:
>> > Gentlemen, Measuring the F/B of any HF antenna in the
>>E-Plane only, is
>> > at best a guess. The only true way to know the real F/B is
>> > in the H-Plane, and there is the problem.
>>I'll second that comment. The worse possible way to measure
>>horizontally polarized HF or lower frequency antennas is at
>>large distances over earth. The longer the distance, the
>>more likely you are to have an error.
>But let's ask a practical question. If you are trying to evaluate a
>horizontally polarized antenna, either versus another or more generally,
>won't the relative signal to a station a mile or two away. as you rotate
>the antenna, give you some indication?
>73, Pete N4ZR
>The World HF Contest Station Database
>was updated on June 5, 2004
>2728 contest stations at
>See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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