In article ,
"Lisa Simpson" wrote:

"Telamon" wrote in
message

.com...
In article ,
"Lisa Simpson" wrote:

Wonderful lesson, thank you! Now I have to learn how to match
antennas
&
receiving systems! : }

Snip

You just have to have the antenna elements the right length.

Which sorta implies an antenna for each frequency you wish to listen
to. I don't have room for an antenna farm, so I have to make do with
one (external) antenna that works for as many frequencies as
possible. I currently have an Eavesdropper C attached to the side of
the house, which seems to be working well, BUT I have a homemade
dipole which seems to work just as well! (used with a RadioShack
DX-394). So far I've logged over 200 frequencies since Christmas
with the dipole, since I just hooked up the Eavesdropper today. So
far I've picked up another dozen new (to me) freq's on the
Eavesdropper.

What I *really* need is the ability to filter receptions; I seem to
now be getting a lot of multiple receptions since plugging in the
Eavesdropper . .

Depends on the type of antenna as some are more broadband than others
but for reception you get the majority of the benefit of a resonate
condition for a band of frequencies. For the most part higher bands
than what the antenna was cut for will be some multiple of it and still
work well so generally you put up the biggest one you have room for.

A dipole will not work well on a band that is 2X the one it is cut for
so avoid that situation and make sure the bands fall on the odd
harmonics.

I'm not sure what you mean by multiple receptions? Some transmissions
by a station are simulcast on several frequencies or do you mean that
your radio is getting false images of some sort?

If you have the false image problem than you can use a pre-selector.
You tune it to the frequency of interest and other signals above and
below it are reduced hopefully to the point the image is not heard.

--
Telamon
Ventura, California