I have used an HF2V here in southwest Florida for about 7 or 8 years. I
ground mounted one with a fair amount of radials, no particular pattern,
some long up to 100ft. some short to about 30ft. Total was about 50. I got
the idea of raising it about my boat dock on a pole at about 12ft off the
ground. Using THREE tuned radials ( what a pain in the neck to get these at
45 degree angle) it played better on both recv and transmit over being on
the ground approx. 10ft from a salt water canal. Being over the canal may
have helped but the tuned radials even though just a few made quite a
difference. Trouble is, it had to be guyed as the winds along the water and
especially during the summer thunderstorm season made it a pain to deal
with. Waterfront lots are smaller and confining. Therefore back on the
ground it went. But it did perform better - elevated - and with
elevated/tuned radials at least here.
I still have it up thought now in my FRONT yard with a Steppir vertical
right over the seawall with the 50 radials in the rear. Nice to able to
switch back and forth.
- Mike
-----Original Message-----
From: Peter FORBES
Sent: Wednesday, November 13, 2013 9:11 PM
To: jim@audiosystemsgroup.com ; towertalk@contesting.com
Subject: Re: [TowerTalk] HF2V Elevated or On Ground
Jim,
Are you really measuring what DXers are really after when comparing vertical
antennas at different heights above ground and ground mounted.?
A DXer is really interested in the signal that leaves and arrives at the
antenna at angles varying from 5 degrees or so and higher above the horizon.
- and in the case of 40 and 80 metres, quite high angles of arrival and
departure.
Surely what is really required is for the measurements to be taken at an
angle above the horizon, such as a distant hill far enough away to be out of
the Fresnel zone and high enough to be looking at the signal above the
horizon.
Measuring a vertical at another location 5 miles away, but at the same
relative height is really measuring the ability of the vertical antenna to
couple to the ground to produce a vertically polarised ground wave.
I seem to remember some W6 stations doing this sort of measurement at
significant angles above the horizon many years ago, using a nearby mountain
range, but they were evaluating vertically stacked horizontally polarised
arrays, not verticals.
Cheers
Peter VK3QI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Jim
Brown
Sent: Thursday, 14 November 2013 12:42 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] HF2V Elevated or On Ground
On 11/13/2013 12:48 PM, James Setzler wrote:
Anyone else have experience with the HF2V mounted up using elevated
radials versus ground mounted with limited on-ground radials.
Over the summer, I did extensive modeling (NEC) of vertical quarter-wave and
vertical dipole antennas, comparing performance on the ground and at typical
roof heights. A report on that work is on my website in the form of a pdf of
the Power Point for a presentation I did at Pacificon last month.
http://k9yc.com/publish.htm
The executive summary -- for all vertical antenna types and almost all soil
quality, roof mounting outperforms ground mounting. The advantage of roof
mounting is greatest for the poorest soil, varying from as much as 8 dB for
very poor soil to a dB or so for extremely good soil.
I did one series of signal strength measurements on a real antenna -- a 20M
vertical dipole that was first measured with the base at ground level, then
at 10 ft, 20 ft, 30 ft, and 40 ft, and finally with the center on the ground
and the bottom half horizontal (at W6GJB). The difference between 0 ft and
40 ft was 10 dB over a 5 mile path (to a vertical antenna at my QTH). The
soil at his QTH is quite poor.
73, Jim K9YC
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