Suburban Chicago has bigger backyards than suburban Southern
California<grin>. The entire lot is 50x100 ft, and the backyard is, maybe,
20x50 feet. Of course, there's also a front yard of the same general size.
(What, are you so unpatriotic as to say I can't have 2 (or maybe 4)
flagpoles? one in the front and one in the back.)
But, the intent of the original question was more generalized than that...
In general, is a shortened dipole better or worse than a shortened monopole
against ground radials, where the max height of both is the same. Seems
it's a tradeoff between matching/loading network losses and ground losses,
and probably (as such things usually are) not a whole lot different (or, at
least, other factors are bigger effects). It would also be interesting to
know about how the tradeoff changes as frequencies go up or down.
Folks like Force12 speak highly of capacitively end loaded dipoles, the
advantages of top hats on short mobile whips are well known, and there is
some theoretical basis for their claims: short antennas with end loads have
more uniform current along the element, which has several desirable effects.
All things being equal, I wonder what the quantitative difference in ground
losses there is between the two approaches (both antennas have part of the
near field in the earth, where power is absorbed, but the distribution is
different).
----- Original Message -----
From: <Jamesnf@aol.com>
To: <keith@dutson.net>; ""'Towertalk'"" <towertalk@contesting.com>
Sent: Thursday, December 02, 2004 2:47 PM
Subject: RE: [TowerTalk] elevated short vertical dipole or
quarterwavemonopole?
> Jim,
>
> You seem to be assuming you can't have an acceptable radial field in a
suburban backyard. I'm in suburban Chicago and had an available space of
only 60' x 40' for my radial field. I centered a Hygain Hytower in the
middle of the space and installed 60 evenly spaced radials varying from
20'(0.15 wl) to 35' (0.25 wl)as space permitted. On 7Mhz, the Hytower
functions as a full size quarter wave which would be within your height
limit. Despite my smaller than optimum radial field, references I checked
said I should have been down only about 1db from a full 120 0.4 wl radial
field. I had no way to measure this, but I can tell you it played very well
on 7Mhz. Don't assume you can't do a radial field that performs well
without own acres of salt marsh.
>
> Jim W9TM
>
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