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Date: Sat, 19 Apr 2014 07:55:15 +1000
From: Richard Rogers <vk7ro@netspace.net.au>
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To: "rsgb_lf_group@blacksheep.org" <rsgb_lf_group@blacksheep.org>
Subject: LF:EWE antenna
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Hello Edgar,

I simulated your EWE antenna using EZENEC4 and saw a cardiod pattern 
with an elevated null to the rear.   But I don't have much faith in the 
results as the ground resistance is unknown.   You would probably get a 
better simulation of a complete loop even if the bottom wire was close 
to the ground.   It seems unnecessary to use the telephone wire as a 
sort of litz if you have 500+ ohm resistor in series with the loop.

I briefly used one of these terminated loops on 7MHz about 10 years ago 
with good results.   When directed on the long path to Europe, the rear 
null was very helpful in attenuating pesky VK3 stations. It worked well 
in my backyard even with the wire draped over shrubbery.   When I put it 
on my flat metal roof, it was not directional at all.   A wire grid 
simulation of my roof showed it to be broadly resonant near 7MHz which 
probably explains why verticals on that roof were never good on 7MHz.

These terminated loops intrigue me, as they are like a vertical dipole 
with the ends bent around and joined together with a poor insulator and 
a loop with a resistor in series.   With the resistor correctly chosen 
they behave just like the active vertical and tuned loop phased together 
which I used on LF when listening to the ZLs on 180KHz in 1997.   
Phasing the two together was not useful in that case because the null 
was to the West where little noise came from at the times I around 
sunset when I was listening.

-- 73, Ric VK7RO