Internet Field Day Challenge Soapbox

Sat Jul 8 00:05:25 EDT 1995

On  6-JUL-1995 01:26:46.3 becker said to JKAHRS
   > My novice station was a bust so Im adding more Tech stations in hopes
   >of gettin them out.  I did find a brand new Extra who just got his
   >initial ticket this year... and sat down to a 80 qso hour on 20
   >meters!!  Nice for his first FD/contest!  (Hank, K2UVG)

There's a sequel to this one....tonight at our club meeting he came up to me
with a 1993 Handbook in hand, wanting to know if the CMOS Super Keyer II was
the same as my keyer he used during FD!......but of course!  He's ready to
build and use..................YES!

Talk about hooked!  Wait till 1996!

73, Hank
Internet: jkahrs at

>From Frank Donovan <donovanf at>  Sat Jul  8 05:23:41 1995
From: Frank Donovan <donovanf at> (Frank Donovan)
Date: Sat, 8 Jul 1995 00:23:41 -0400 (EDT)
Subject: High vs Low
Message-ID: <Pine.OSF.3.91.950708000103.8050C-100000 at>

Hi Ed!
My intent in introducing the concept of an isotropic source over a perfectly 
reflecting half space was to clarify why 6 dB gain is produced at the peak of 
EVERY lobe.  For each lobe with 6 dB gain there is a compensating null with
little-to-no energy!  At low heights there are one or two big lobes and a
corresponding number of large nulls.  As the antenna 
height is raised, the total AREA occupied by the peaks and nulls remains 
constant (half of the sphere is illuminated by lobes and half is "dark" 
as a result of nulls), only the total NUMBER of peaks and nulls increases.

Horizontal polarization over real ground typically approximates 
performance over a perfectly conducting half space withina few dB provided 
there is not excessive terrain roughness at the near region of the Fresnel 
zone (roughness exceeding 1/4 wavelength).

Vertical polarization, however, typically results in Brewster angle 
cutoff due to dielectric constant induced phase shift at angles near 10 
degrees and below (actual value depends on soil conditions in the Fresnel 
zone).  By the way, inefficient reflection of vertically polarized waves
over continental land masses, especially at low angles, is one of 
the factors resulting in lower signal levels on DX paths over land paths
vs. similar sea paths.

Regarding gain figures for HF antenna arrays, I trust the values produced 
by modern antenna models such as NEC.


>From Frank Donovan <donovanf at>  Sat Jul  8 05:29:27 1995
From: Frank Donovan <donovanf at> (Frank Donovan)
Date: Sat, 8 Jul 1995 00:29:27 -0400 (EDT)
Subject: Contest Antenna Questions
Message-ID: <Pine.OSF.3.91.950708002523.8050D-100000 at>

Hi Scott!
Its sure great to hear from you again!
The HDBX tower is not safe for large antennas that are capable of 
producing large moment, because the rivets in the tower will fail.  One
approach that avoids this problem is to install a mast all the way from 
the foundation to the top of the tower, so that the mast takes the twist, 
and the tower, in effect, is just a support for the mast!  Small antennas 
with great ops still produce great scores OM!
Hope to CU again on the east coast!

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