In message , bilou
writes

"Brian Howie" wrote in message
...
The questions I have a- Were Tonna being overcautious ? Is my modelling
software inadequate for boom effect modelling .
Hi
I think he used the same pilars on his 10cm beam that is fed from a
rectangular wave guide above the boom.
It seems he was also using them for 900Mhz yagis made for the american
market.
I can't be sure as I only have the 10 cm beam here.
It's elements are 4 cm above the boom.
One problem I remember from the 55 elements was QSB during high winds
but I am not sure if it was due to boom bending or rotor slackness.



Thanks. I've been reading around. It seems NEC models current flowing in
the centre of a wire, so simulating the boom with a thick wire isn't
going to work. I tried putting 3 thin wires spaced 1/4" about 1cm below
the elements, and it screws the impedance and radiation pattern.

I could simulate the boom with a wire frame model , but it might be
easier using taller pipe clips.

73 Brian GM4DIJ
--
Brian Howie