"Ken Bessler" wrote in message
news:O3Dig.40117$4H.36191@dukeread03...

"Cecil Moore" wrote in message
. com...
Ken Bessler wrote:
If I prune the driven element on my 6m 3el quad for best
swr, do I have to do anything to the reflector or director?

For beams, the desired radiation pattern is usually
more important than minimum SWR. Using EZNEC, I've
seen a 4:1 SWR yield the desired pattern where
at the minimum 1.5:1 SWR point the F:B ratio was
terrible.
--
73, Cecil http://www.qsl.net/w5dxp

I did model this antenna with EZNEC but I forgot to take
into account the fact that the wire used is insulated. I think
that screwed up the resulting antenna. Maybe? Would an
insulating jacket reduce the VF of the wire? I've accounted
for everything else, wire gauge/loss, ant height, type of
ground, etc.

Ken
KG0WX

OK now I'm really starting to think I should prune my reflector
and director - here's a quote from the ARRL Antenna Book
2003, page 12-4:

"In practice, it has been found that the length around the loop
should be approximately 3.5% greater than the self-resonant
length if the element is a reflector, and about 3.0% shorter than
the self-resonant length if the parasitic element is a director."

I built my 6m quad with a 240.64" driven element which I had
to trim 6" to get the SWR where I wanted it (low end of 50mhz).

My reflector is 246.64" and my director is 233.41".

Help? Do I trim or not? I have done some tests with the ant
up and I'm noticing my F/B ratio is not as good as the EZNEC
model predicted (30.62 db predicted, I'm seeing maybe 2-3db)

Ken KG0WX
Always learning......