Topband
[Top] [All Lists]

TopBand: Elevated GP vs. Vertical Antennas

To: <topband@contesting.com>
Subject: TopBand: Elevated GP vs. Vertical Antennas
From: k6se@juno.com (Earl W Cunningham)
Date: Sun, 22 Mar 1998 00:58:13 EST
Carl, KM1H said:

Possible use of antenna design that does not include earth return current
    dependency for the feedpoint (some form of  vertically polarized
loop)

Eric, N7CL said:

What does EZNEC have to say about a full size loop, vertically
polarized, base 8' above the ground?  F/B is of no concern to me
but maximum ERP is...and at the lowest possible angles.

EZNEC says:

"Diamond" loop with bottom corner 8' high, fed at side corner for
vertical polarization:  Gain = 2.25 dBi @ 18.0 degrees TOA.

"Square" loop with bottom 8' high, fed at center of side for vertical
polarization:  Gain = 2.06 dBi @ 20.5 degrees TOA.

"Delta" loop, equilateral triangle, base horizontal and 8' high. 
Feedpoint adjusted for max vertical polarization:  Gain = 1.91 dBi @ 20.9
degrees TOA.

Same "delta" loop, but inverted, with "apex" 8' high.  Feedpoint adjusted
for max vertical polarization:  Gain = 1.90 dBi @ 18.1 degrees TOA.

Results are for full-size (1 wavelength) loops resonant at 1.830 mHz and
above "good" (5mS/m) ground.  Gain increases and TOA decreases if soil
conductivity is better than "good", and vice-versa.

Earl, K6SE says:

You might consider a non-ground-return-dependant, vertically polarized
antenna that is much less unwieldy than the above full-size quad and
delta loops (which require support(s) anywhere from 160' to over 200'
high).   A choice such as the so-called "magnetic radiator" type of
antenna for 160m would require two supports about 52' high with the
bottom of the antenna 8' high.  EZNEC says the following for such an
antenna, resonant at 1.830 mHz and erected over "good" soil:  Gain = 2.11
dBi @ 24.4 degrees TOA.

73, de Earl, K6SE


_____________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com
Or call Juno at (800) 654-JUNO [654-5866]


--
FAQ on WWW:               http://www.contesting.com/topband.html
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Problems:                 owner-topband@contesting.com

<Prev in Thread] Current Thread [Next in Thread>