Topband: RDF

[James Wolf]

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 at contesting.com] On Behalf Of David Cole
Sent: Friday, January 25, 2013 4:27 PM
To: topband at 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
_________________
Topband Reflector