I just did a few quick simulations. It turns out that as height of the
antenna increases, the gain difference between horizontal and vertical
polarization decreases. Here are some results for a two element 10 meter
quad as a function of height and polarization.
Height_____Horz______Vert___Difference
25_________11.8______6.6______5.2
30_________11.8______7.1______4.7
40_________12.4______8.0______4.4
50_________12.4______8.7______3.7
100________12.7_____10.5______2.2
The difference is getting smaller as height goes up. A two element quad
at 50 ft to the boom, which is pretty high for a 10 meter antenna (K3LR
obviously doesn't think so), only has a 3.7 dB far field difference.
This could be hard to measure without some accurate equipment and a good
test range. I did not simulate a 4 element version.
Jerry, K4SAV
George P. wrote:
>Gents,
>I would not feed only with vertical... That would make no sense to me. Feed
>Both polarities with separate feedlines!!! Then you can choose either, or
>both with phase shift if you want to play with circular. I have compared the
>vertical and horizontal patterns independently on my quad and found that at
>50 feet to the boom, they are very close. At less than 36 feet (<1
>wavelength, no tests were done) I would think the horizontal polarization
>would be more affected, since the elements are in the same plane as the
>ground. BTW... Both have >30 dB front to back and a little more off the back
>corners (4 elements) at 50ft with my design. Gain of the vertical feedpoint
>on the quad over the antron99 is about 10/12dB. I had no dipole to compare
>for the horizontal polarization gain comparison test.
>George AB2KC
>
>----- Original Message -----
>From: "K4SAV" <RadioIR@charter.net>
>To: <towertalk@contesting.com>
>Sent: Sunday, January 08, 2006 9:10 PM
>Subject: Re: [TowerTalk] 10 Meter Beams - Any IDEAS
>
>
>
>
>>OK, I'll concede one point.
>>
>>If your interested in local ground wave contacts, then the fact that you
>>lose most of the antenna gain with a vertically polarized quad, probably
>>doesn't matter. But I don't think it's the kind of thing a contester
>>would be interested in doing.
>>
>>Jerry, K4SAV
>>
>>K4SAV wrote:
>>
>>
>>
>>>I would not recommend feeding an HF quad with vertical polarization. If
>>>you do that, the antenna pattern is no longer reinforced by ground
>>>reflections, and you end up with something that has less than free space
>>>gain. If you have a UHF antenna that is far enough above ground to not
>>>care about ground reflections, then maybe it doesn't matter.
>>>
>>>Jerry, K4SAV
>>>
>>>George P. wrote:
>>>
>>>
>>>
>>>
>>>
>>>>Michael,
>>>>Quads rule. 4 elements minimum and you'll be on top. Set driven element
>>>>up
>>>>for both vertical AND horizontal. Use same feedline length for each
>>>>polarity, and you can play with circular polarization if you add 90
>>>>degrees
>>>>phase length (1/4W) in one of the feedlines. Vertical is great for late
>>>>night ground wave for mobile contacts, state to state <200 miles and the
>>>>local repeaters. You may e-mail me for more info on how to set it up.
>>>>When
>>>>the band dies... there's always guys on groundwave using A99 verticals.
>>>>George AB2KC
>>>>
>>>>----- Original Message -----
>>>>From: "Michael Mark" <m2eng@mts.net>
>>>>To: <towertalk@contesting.com>
>>>>Sent: Friday, January 06, 2006 8:32 PM
>>>>Subject: [TowerTalk] 10 Meter Beams - Any IDEAS
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>I like contesting and have the Canadian 10M Phone LP SSB record which I
>>>>>did
>>>>>in 1991 with about 2500 QSO's.
>>>>>
>>>>>I used a Hy Gain LJ105 on a 48' tower back then at my old QTH.
>>>>>
>>>>>I have a couple of bucks now so I want something better for the upcoming
>>>>>Sunspot Cycle increase.
>>>>>
>>>>>I have a 48' tower at my office building with nothing on it.
>>>>>
>>>>>As well, my flat building roof is 65' x 45' with 16' in height.
>>>>>
>>>>>I have new: A Stack Match for 2 antennas, new Ham IV and 2 Hy Gain
>>>>>LJ105CA's and a Glen Martin 8' Roof tower.
>>>>>
>>>>>I was also considering a M2 10M7 or a Force 12 MAG 810 as well.
>>>>>
>>>>>Just asking for some ideas or experiences from you Contesters about your
>>>>>10M antenna recommendations.
>>>>>
>>>>>Tnx
>>>>>
>>>>>Michael Mark, P.Eng., VE4MM
>>>>>_______________________________________________
>>>>>
>>>>>
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