David,
As I recall, you take the average gain and subtract it from the maximum gain.
Or
Use 4NEC2, it calculates it for you.
Jim, KR9U
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of David Cole
Sent: Friday, January 25, 2013 4:27 PM
To: topband@contesting.com
Subject: Topband: RDF
How do I calculate RDF – I am currently modelling the Shared Apex Loop antenna
recently described in QEX and QST , Not to be confused with the following
months article on phased K9AY’s - I have an 8 direction antenna up and running
and now wish to add 8 more elements to the array. I will then have three shared
apex loops in anyone of 8 directions. I have using Eznec modelled the array and
the optimum spacing is around 50 feet and the phase delays 0 100 200 appear to
give good F/B and F to side – this leaves me to the original RDF question – in
Eznec the Average Gain is calculated – now is the same average gain that the
RDF formula needs? It does appear to coincide with figures quoted in the
original article for a single array rising to 12.1 db for the three in line
array. However if I use the same method and model my 8 Element full size 80m
array then the results are not as expected when I try and calculate RDF.
Dave
g3rcq
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