"Thomas Magma" wrote in message
...
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

Hi Thomas

I think you can design and develop a very good colinear coaxial array at
UHF using copper pipe. Do you have any requirement for VSWR? Do you have
need for operating the antenna at other than one frequency? It isnt easy to
develop a good UHF colinear without good test equipment. How will you
measure input impedance? Do you care about the angle of the radiation
pattern maximum? End fed colinears will have beam squint with frequency
change.

Jerry KD6JDJ