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Old March 12th 08, 04:12 AM posted to rec.radio.amateur.antenna
Richard Harrison Richard Harrison is offline
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First recorded activity by RadioBanter: Jul 2006
Posts: 588
Default Antenna physical size

Art wrote:
"Why can`t you do that vector trial have you forgotten that old
electrical stuff?

Not completely but it serves little purpose in this arena. I admit that
being retired for decades requires me at times to search my memory for
awhile to retrieve something stored there but that is where the books
come in as reminders.

Richard Clark noted that "size counts" appears on page 3 of Ed Laport`s
"Radio Antenna Engineering". Richard was right:

"---concerns the field around a very short doublet in free space
composed of a straight conductor of length l in which a sinusoidal
alternating current of frequency f is flowing. The current is assumed
to be uniform throughout the length of this doublet."

The above exerpt is sufficient to show the field around a very short
(elementary) doublet in free space is a function of length l as
previously reported from page 864 of Terman`s 1955 opus. The old masters
agree. So call me a parrot already. I don`t care.

I gave you examples of my experience with microwaves. These showed
antennas with the same polarizatiions have the least path loss.
Polarization diversity in addition to space and frequency diversity has
been used to improve reception and reliability on mivrowave paths. When
one polarization, position, or frequency falters, a switch is
automatically made to the other alternative. Reliability is greatly
improved. Surely other readers have had similar experiences with antenna
alignment to receive the best signal. It requires that the antennas be
parallel. Crossed antenna polarization on line-of-sight paths causes
huge (30 dB?) loss.

FM broadcasting began with horizontally polarized antennas. Automobiles
using vertically polarized antennas required FM broadcasters to add
vertical polarization to serve a mobile audience.

Best regards, Richard Harrison, KB5WZI