TopBand: EWEs

[Earl W Cunningham]

Eric, N7CL commented that Ewes perform better over better ground.

This might be true only because the ground conductivity greatly affects
the TOA (in this case, the angle of max reception), but this is true for
all antennas, no?.  Ewes over very poor soil can be good performers
without building a ground screen for them  -- read on.

Eric also said that Ewes are size-critical, but he said this is because
if the Ewe is small, it doesn't produce enough signal.  Any Ewe, large or
small, can be made resonant on the desired frequency by inductively
loading it at the feedpoint.  Doing so does not alter its directional
pattern and, no doubt, will produce a much larger signal.  A resonant
loop doesn't need a preamp with so much gain that its noise overwhelms
the signal from the loop, does it?  A resonant Ewe may not even need a
preamp at all.

An Ewe antenna is indeed size critical, but not for the reason given by
Eric.  As I previously posted, the optimum size for an Ewe is *highly*
dependent on the type of soil over which it is erected.  Poor soil
conductivity requires a smaller Ewe than good soil conductivity.  The
correct termination resistance varies, of course, depending on both the
soil and the size of the Ewe.

Eric's idea of installing a ground return wire which connect both ends of
the Ewe together is a good one.  EA3VY, the first to come up with this
idea to my knowledge, has shown that the ground return wire is an
effective way to minimize the effect of different soil condutivities
(which may be a different reason for the ground return than Eric's).

I previously posted the parameters for optimum-size Ewes modeled over
"very poor", "poor", "good" and "very good" soil conductivity.  Anyone
who didn't read that post and would like to have the info, e-mail me
direct and I'll send it to you.

Eric, let me know if you use EZNEC.  If so, I'll attach and send the
model files for optimized Ewes to you.

73, de Earl, K6SE


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