[Elecraft] Antenna?

[Ron D'Eau Claire]

I haven't done "pedestrian mobile" like the "Packers" but I have used a
vertical with single "counterpoise" with a total length of 1/2 wave like
that "reference vertical" they show on the web page would be on 20 meters.

First, we ARE talking verticals now, and a vertical has about a 6 dB
disadvantage over a horizontal, provided the horizontal is about 1/2 wave
high! That's not likely to happen below 10 meters on a portable or
pedestrian mobile setup, so it's a moot point here.

That aside, what is interesting about a vertical with one horizontal
counterpoise wire is that the counterpoise radiates as much as the antenna.
Typical "ground-plane" arrangements provide a lot of cancellation of
radiation from the "radials" since then are generally opposite each other
and fed "in phase" (all connect to the same electrical point, not to
out-of-phase currents like a dipole fed at the center). With only one
counterpoise, there is no cancellation. 

That produces a lobe straight up for NVIS propagation from the counterpoise
that is virtually as strong as the lower angle lobe. Also the antenna
becomes fairly directional (in the direction of the counterpoise) which
helps provide some gain to overcome the near-ground losses when hanging from
a pedestrian <G>. 

That combination can be dynamite for what a H-F Pack operator wants - a
great mix of radiation angles supporting ground wave and sky wave contacts.
The only consideration seems to be that it will probably help to have the
counterpoise sort of generally pointing in the direction of the other
station for ground wave communications, although the "directivity" is going
to be very broad. Also, with the counterpoise literally "on the ground" that
high angle radiation will be greatly affected by the condition of the earth
under it.

Ron AC7AC



-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Brian Mury
Sent: Sunday, July 04, 2004 10:20 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Antenna?


On Sun, 2004-07-04 at 06:47, Mike Morrow wrote: 
> It confirms the very dismal performance of *all* those "popular" HF 
> short loading-coil verticals in comparison to the most simple, basic, 
> inexpensive quarter-wave vertical.  TANSTAAFL!

It's no surprise that a full size quarter wave beats any loaded vertical,
but I disagree that they all have dismal performance. The best 5 are less
than a 1 dB difference (with the best being a mere 0.3 dB difference). The
best 13 are under 6 dB, which is less than 1 S unit. Only 4 have a greater
than 1 S unit difference.

>...
-- 
73, Brian
VE7NGR