On Nov 9, 1:23 pm, Tom Horne wrote:
Is it possible to ask questions here without triggering an arcane debate
about competing views of theory. I'm about to find out. I asked
earlier in another thread what measuring instruments I would need to
have the use of in order to compare the effective radiated power of
different antennas. As near as I can tell there was no answer.

I built a collinear J pole using copper tubing. I'd like to know if it
is more or less effective at radiating whatever works to the stations
I'd like to be able to talk to under conditions of emergency operation
then say a collinear ground plane or any other omni directional antenna.

I would like to deploy the most effective practical antennas that field
testing can devise and not have to wait until the next breakthrough in
physics to be able to get my local governments Email out to my county's
government, the state government and the responding relief forces.

My question, again, is what measuring instruments can be effectively
applied to the comparison to provide results that will be born out by
real world performance. I have to admit that I find the endless
theoretical debate wearying. As long as it continuous then the
newsgroup will be useless to newer licensees, like my self, who would
like to get some "patient council to the beginner" from those of you who
have been there and done that. Before I have to go there and do that
would be soon enough.
--
Tom Horne, W3TDH

So, given that you want an omnidirectional antenna ("flat pancake"
radiation pattern), if I were in your shoes, I'd place a field
strength meter far enough away from the point at which I'm placing
each antenna I'll test that it's well into the far field, and then
install the antennas I want to test, feed them power from the
transmitter I'll be using, and see which gives the highest indicated
field strength. Note that you can take a liberal interpretation of
"field strength meter." It might well simply be the received signal
strength indication on a receiver at one of the remote sites you want
to communicate with. Note that this is getting really close to
testing exactly the condition you want to optimize. Why do otherwise
unless you have to? Why not try to optimize the communications on the
path that's giving you the most trouble now, and then verify that all
the others still work at least that well? You asked what instruments
can be effectively applied to provide results that will be borne out
by actual performance--to me, the best is a test of the performance
itself.

Implicit in this, to me, in the name of efficiency, is that you can
try modelling some candidate antennas before building/buying physical
versions to try out.

Also, you're not the first person to have this problem, and others
have solved it various ways. You very well may be able to get
recommendations from people who have. You may be able to borrow some
of the common commercially available antennas to try, too.

Since the antenna itself is only one component of the overall
communications channel, it seems to me that it would be good for you
to step back and look too at other aspects of the channel. If you
have limited resources to put into the project, it may well do more
good to get a modest antenna up high at each site, than to put a "high
gain" antenna in a bad location (e.g. too low).

I suppose there will be several people who will disagree with this and
get into theoretical debates about why it can't be so, just as you
say. But don't let that keep you from trying real antennas and
finding out what really solves your particular problem.