I think the key here is that you were able to raise your vertical well over
1/2 wavelength on 15M. The discussions I've read here about elevated vs
ground-mounted verticals indicate you really have to get them up high (was
it over 1/4 wavelength or 1/2 wavelength?) for optimum performance.
Unfortunately, that's a tough requirement at 40M, 80M, and 160M, where
verticals are often the most practical solution.
73, Dick, WC1M
-----Original Message-----
From: John Langdon <jlangdon@outer.net>
To: TowerTalk <towertalk@contesting.com>
To: <towertalk@contesting.com>
Date: Thursday, July 23, 1998 10:14 AM
Subject: RE: [TowerTalk] Antenna Comparisons
>
>When I was a novice, I lived in Corpus Christi, Texas, in high conductivity
>soil about 3 blocks from the Gulf of Mexico. Crystal controlled on 21.106,
>I became a DXer. Every time I would hear something and not work it, I
>would go out and install three more radials in the ground around my 14AVQ.
> I ended up with more than 60 countries and more than 60 radials. When my
>general ticket arrived, I put up a 40' Rohn push up mast with a 108" mobile
>whip at the top with a loading coil at the base of the whip and four
>sloping radials. I carefully tuned the coil and radial length for
>resonance and adjusted the slope of the radials to lowest SWR. On 15M, the
>elevated GP beat the 14AVQ ground mount every time in every direction at
>every distance except 3 blocks away. A three element "Gotham" beam
>anybody ever modeled one of those historical curiosities?) at the same
>height as my GP was slightly better (less than 3 db) than the GP. And that
>14AVQ was probably in the best possible environment for a ground mounted
>vertical (although I guess I could have been 1/4 wave from the water ala
>6Y4A). In Central Texas soils where I live now, I won't even consider a
>ground mounted vertical, but a would do an elevated GP if that was fit for
>the space and supports available.
>
>-----Original Message-----
>From: Tom Osborne [SMTP:w7why@mail.coos.or.us]
>Sent: Thursday, July 23, 1998 1:03 AM
>To: TowerTalk
>Subject: [TowerTalk] Antenna Comparisons
>
>
>Hi All
> Last week I was on an extended camping trip and thought I would
>take the rig along to pass the time. I wasn't sure what type of antenna
>to use, so I did some experimenting.
> The first antenna was an elevated 20 meter ground plane with the
>base about 10 feet in the air. It seemed to work real well as worked
>some good stuff on it. Not being satisfied, I took it down and put up a
>delta loop at about 30 feet. It didn't work nearly as well as the
>elevated 20 meter G.P. with 4 radials. I've seen posts on the reflector
>about elevated GP's but I didn't think the elevated GP would work that
>much better than the delta loop. I think I'll raise the verticals I
>have here and see if they work better. 73
>Tom W7WHY
>
>
>--
>FAQ on WWW: http://www.contesting.com/towertalkfaq.html
>Submissions: towertalk@contesting.com
>Administrative requests: towertalk-REQUEST@contesting.com
>Problems: owner-towertalk@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|