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LF:EWE antenna

To: "[email protected]" <[email protected]>
Subject: LF:EWE antenna
From: Richard Rogers <[email protected]>
Date: Sat, 19 Apr 2014 07:55:15 +1000
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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


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