"Jeff Liebermann" wrote in message
...


snip

As for your lack of an antenna analyzer, this is actually a good
thing. What you really want to do is see what the antenna is doing
over a wide range of frequencies. For that, I suggest a return loss
bridge. I use a Telonic Rho-tector Model TRB-50 and a Texscan RCB-3.
Here's what's inside:
http://www.qsl.net/n9zia/rlb/texscan.png
Both will go from 0.5MHz to 1GHz. All you need is a decent RF sweep
generator, oscilloscope, terminators, and cables. You can see the
VSWR curve over the frequency range while you're tuning. You can also
do the same thing with a directional coupler and a diode detector, but
I think the return loss bridge is easier. I've also built a few for
microwave frequencies (2.4 and 5.7GHz).

I have the o'scope and a sweep generator/ spectrum analyzer combination to
provide the RF. I'd have to check to see if the generator provides a sweep
signal for the scope's external horizontal input.

The bridge looks like a one-evening project although I might have to
hand-make those 1% resistors.

By the way, I found a way of using the sweeper/spec-an combination as a
crude antenna checker. I loop the generator directly into the analyzer, but
use a T-connector at one of the ports. Of, course, it produces a clean,
flat line. Next, if I connect an unterminated length of cable to the
T-connector, I see a comb pattern produced by reflected energy. (The comb's
appearance is dependent on the length of the cable and the test setup.)
Lastly, with an antenna on the end of the cable, the comb goes flat at the
frequency (ies) where the antenna is radiating ... reduced reflections at
some freqs since the antenna is radiating most of the forward power. It's
an interesting effect to observe but not sensitive enough for much more than
a GO/NOGO check.

If I put the T-connector at the antenna, itself, with one cable each to the
sweeper/spec-an, the pattern changes somewhat but I haven't analyzed what I
see.

"Sal"