"Richard Clark" wrote in message
...
On Sun, 9 Apr 2006 12:45:06 -0500, "Ken Bessler"
wrote:

New antenna is a 16 element coaxial collinear @32' agl.
Total transmission system losses work out to 5.299db @2.412
ghz (includes feedline + N connectors).

So, why does this antenna only have about (rough measurement)
1-3 db gain over the stock antenna? I was meticulous in my work,
measuring the antenna parts with a digital caliper and checking
the connections with a DVM along the way.

Maybe my design is a fault?

Hi Ken,

What did you compute as being the Velocity Factor for the shield being
covered with thick PVC?

The problem with this modified Franklin Array is that you are cutting
for half-wave dimensions once, for two Velocity Factors along the same
length. Only one is going to be correct, and it is going to impact
the theoretical application of the other.

You might want to try again using bare wire, twin lead fashion.

73's
Richard Clark, KB7QHC

To Ken

Hi Ken, I'd always take Richard's advice before mine. But, I wonder if
you realize how difficult your task is. It is a very difficult project to
develop the design of any array of radiators thats about 5 wavelengths long.
And, it *is* a project, not just a matter of precise measuring and cutting.
I'd think that 3 dB improvement over the antenna that was designed for
optimum performance shows that you are doing something right.
This project is a great learning opportunity for you.

I'd suggest that you get a directional coupler and get some idea of the
match of the array while it is being made longer. If you can manage to keep
the VSWR under 2:1 with 6 or 8 elements, at your operating frequencies, you
will be way ahead of me.

Jerry KD6JDJ