On Nov 25, 5:55*pm, "Thomas Magma"
wrote:
Hello,

I am about to attempt to build a UHF collinear coaxial antenna and am trying
to finalize a design. I have done a lot of reading and am a little confused
on a few things. First off I have read contradicting statements whether to
use odd or even number of 1/2 wave elements. 1, 3, 5... or 1,2,4... Also I
don't understand what the 1/4 wave whip is doing on the top without a ground
plane (found in most designs), is this necessary for a receive antenna?.

Instead of using coaxial cable, I will be building the 1/2 wave and 1/4 wave
transmission lines out of ridged copper pipe with air as it's dielectric in
order to maximize the velocity of propagation and therefore making true 1/2
wave elements. Does anyone see anything wrong with this approach?

Thomas

I just built one of these using thin wall 1 1/4" aluminum tubing and
bare 20ga copper wire for inside. It was a tri band
for 50, 144 & 440 mhz, section = 1/4 and 3 x 1/2 wave then top 1/4
section cut for 146mhz. SWR is higher than I
like but it receives and signal reports are so much better than my
factory 5/8 antenna I will now try to lower the swr.
I used short pieces of PVC to couple the tubing, its freestanding and
15' tall, very light weight, I used old swmming pool cleaner
telescopic pole for the elements.

N4aeq

unaxesc