Bill

First - I want to be clear that I have absolutely no problem with using
the term GAIN for describing antenna performance.
I did think had not been established, in this thread, that an antena's
gain has to be referanced to some standard antenna, like a dipole or
theoretical radiator like 'isotropic'. I'd submit that, what we refer to as
antenna gain could be more accurately be called 'specific gain'. I also
tink that the term Directivity clears up any misunderstanding about what can
be done to improve an antenna's performance. And, I realize that my
thinking about Gain and about Directivity dont imply that anyone needs to
exclude either from their vocabulary

I suspect my caution about antenna gain stems from reading specs that
display extremely high "gain" numbers while the antennas are actually quite
ordinary.

Jerry


"Bill Turner" wrote in message
...
On Sat, 10 Apr 2004 15:59:56 GMT, "Jerry Martes"
wrote:

I'll be carefull if you'll tell me how to do it.

Jerry

__________________________________________________ _______

Only one "l" in careful Jerry, not a good start. :-)


1. Decide on your reference, most likely a dipole.

2. Measure the field strength of the dipole in its most favored
direction.

3. Measure the field strength of the antenna under test in its most
favored direction.

4. Calculate the gain or loss of the antenna under test.

5. Post the results here and be prepared for an onslaught of criticism.

--
Bill, W6WRT
QSLs via LoTW

I suspect my caution about antenna gain stems from reading specs that
display extremely high "gain" numbers while the antennas are actually
quite
ordinary.

Absolutely. Whenever I see a gain number that dosen't reference something,
I assume they mean dBi, rather than dBd.

Dave VanHorn wrote:
Absolutely. Whenever I see a gain number that dosen't reference something,
I assume they mean dBi, rather than dBd.

Looks like some antenna retailers reference dBdl. :-)
(dl stands for dummy load)
--
73, Cecil, W5DXP



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"Cecil Moore" wrote in message
...
Dave VanHorn wrote:
Absolutely. Whenever I see a gain number that dosen't reference
something,
I assume they mean dBi, rather than dBd.

Looks like some antenna retailers reference dBdl. :-)
(dl stands for dummy load)

I've seen a few antennas that should be spec'd as negative dBdl.

On Sun, 11 Apr 2004 13:31:22 -0500, Cecil Moore
wrote:

Dave VanHorn wrote:
Absolutely. Whenever I see a gain number that dosen't reference something,
I assume they mean dBi, rather than dBd.

Looks like some antenna retailers reference dBdl. :-)
(dl stands for dummy load)

Actually it appears as if some manufacturers only measure the
directivity and express it in dB :-), completely ignoring the
efficiency, which is often quite low in "exotic" antenna designs.

An exotic antenna design with directivity 10 (10 dB) and 10 %
efficiency will have a 0 dB gain and will produce the same effective
radiation power (ERP) as an omnidirectional (directivity 1 or 0 dB)
antenna with 100 % efficiency when using the same transmitter power.

Paul OH3LWR