Modelling numbers for a 20 x 140 DKAZ to back up what I said: - best null is
-42 dB and the -6 dB null width is 72 degrees. - lower the termination by 80
Ohms and the best null (straight off the back) is only -29 dB but the 6 dB null
width jumps up to 106 degrees.
Chuck
From: charle...@msn.com
To: irca@hard-core-dx.com
Subject: RE: [IRCA] [NRC-AM] DKAZ Antenna
Date: Fri, 21 Aug 2015 21:41:51 +0000
This is a repeat of my earlier comment to Nick, where I guessed / thought that
the minima does not really move.
Ad I see it, the issue here is that the best null is the sharpest (narrowest)
null. If you want a null to cover something off to the side a bit, you can
indeed "mis-terminate" and get a wider null that hits the off-to-the-side
station. The price you pay is a degraded null in the backwards direction.
The way to prove this is to record termination and signal strength data for
someone directly in the null and someone off to the side. That's tough to do
from Grayland is you choose to face the antenna west for DX - there are few
stations directly in the eastward null. Unfortunately for testing purposes, it
would be better to face the antenna SW or SSW.
Chuck
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