> One of the tests I performed involved a short 1 inch wire off the
> end the end of a 50 ohm coax (small monopole) and a 1 square inch
> loop antenna off the end of another 50 ohm coax....
> Well, the short of it is, they aren't much different from one
> another. Oh, if you pull out the magnifying glass, you'll see in
> some places a maximum diff of possibly 3dB, but not much anywhere
> else. I waited a couple of days and repeated the tests with the
> same results.
> Is this to be expected? Am I looking a virtual point sources in the
> far field so it really doesn't matter if they're stubs or loops?
Yes, it's to be expected. However, see below.
> I went further and compared a 4 inch monopole against a 4 inch
> dipole. Turns out the monopole does better than the dipole.
Since you haven't mentioned a balun or common-mode choke, I suspect
that in each case the outside of the coax was part of the antenna. In
the case of the monopole, it pretty much had to be. That is, E-field
lines leaving the monopole had only one place to go: the outside of
the coax.
-C.
Received on Sat May 13 2000 - 11:05:05 EDT
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