Sum Ting Wong wrote:
On Sat, 27 Dec 2008 21:24:44 GMT, "Dave" wrote:

efficiency is only one measure of antenna performance.

Exactly. You get it and JS doesn't.

S.T.W.

Oh, "I get it", you guys just don't get the lack of importance to your
point(s!)

Correct match to you rig does NOT affect the antennas efficiency, you
would still want the most efficient antenna.

Antenna length does relate to efficiency, and normally you would erect
the longest possible for the freqs, and the efficiency of the antenna is
improve, if by nothing else, than capture area ... however, you must
balance this against the antenna pattern you wish.

The pattern of the antenna, which will be identical in both T/R, is
important. Antenna efficiency is important. Match to feedline, and
feedline to rig is important.

You seem to feel that s/n ratio is something to pursue, I tell you it is
not. This is actually handled in the antenna pattern, you do NOT want
the antenna to be receptive in the direction(s) of noise sources nor
have it prone to static charges and disturbance ... antenna design is
what controls this.

Your main problem is that you wish to separate all the elements out and
be able to deal with each one separately--you can't, every added
capacitance adds some measurable amount of inductance, every added
inductance adds some measurable amount of capacitance.

There is never a case when you wish to decrease antenna efficiency,
well, unless you are attempting to construct a dummy load ...

If the antenna is "too sensitive" (efficient), crank your rf gain down a
bit to the noise floor ...

However, if I was supporting a poor antennas' use, or selling a poor
antenna, lack of attention to efficiency would be my first "selling point!"

Let me repeat, there is NEVER a time a ham or swl'er will want lack of
efficiency--they have rf gain controls and other "attenuation boxes" to
handle that--you obviously are attempting to confuse antenna efficiency
with another aspect of antennas ... indeed, efficiency can be applied to
most aspects of an antenna, i.e., "most efficient length", "most
efficient match", "most efficient placement", "most efficient design",
"most efficient pattern", etc.--and these CAN all vary as to the
antennas intended use ... you can never make one change in antenna
design which DOES NOT affect all others--i.e., one change makes many ...
it is why EZNEC and MMANA-GAL are so desirable to toy with ... load up
the software, make one change, watch it affect all others ... well, most
of the time.

Regards,
JS