Lynn,
I promise not to go in to tons of details, but radio
antennas share something in common with musical instruments.
While the physics of air don't seem to have a lot in common with
electrons, they do create resonances which are based on the size
of the paths that the electrons or air molecules follow so low
frequencies such as a base pipe organ note or a bassoon require
physically large pipes to make the low notes. piccolo and
penny whistles are small because they make high notes and the
airways must be very short.
Radio antennas are governed by the same natural laws
except that it is not air but electrons that bounce around in
conductors which behave just like organ pipes only for
electrons. That means antennas for low frequencies such as HF
must be physically larger than antennas for VHF 2-meters and UHF
70-CM and above.
There are tricks you can play, however, to make
low-frequency antennas smaller than they normally would be but
still resonate. Nothing comes for free, though, and the tradeoff
is efficiency.
The RSGB and ARRL have all kinds of books on how to make
various types of antennas and there are sections on what are
called "stealth antennas." These are antennas either disguised
as something else like a flag pole or are made out of materials
that are very hard to see such as fine wire.
The fine wire antennas break more often, of course, but
some are almost invisible.
Stealthy antennas are designed for amateurs who either
have fussy neighbors or who are forced to live in neighborhoods
with bans on outdoor antennas.
The books tell you how to build such antennas in a safe
manner so that you don't expose yourself or your neighbors to
high-level electromagnetic radiation which may or may not be
harmful to the body and can sometimes disrupt consumer
electronics such as music systems, computers, etc.
The wave lengths such as 2-meters, 6-meters, 70
centameters, etc, describe the distance between the waves as
they fly out from the antenna like ripples on a pond. In this
case, they fly at the speed of light.
"Mrs. Lynnette Annabel Smith" writes:
> Gordon is, like you, a radio amateur. I think he's talked about that
> before; and it's something which we would like to bring back within his
> reach but due to problems on the premises the only antenna he currently
> can have is a 2 meter and 70CM vertical; I don't understand the technical
> bits of that. But an HF antenna is out of the question now as we don't
> have a great deal of space, and we no longer have cooperative neighbours.
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