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Old August 18th 08, 05:26 AM posted to rec.radio.shortwave
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Default Active Antennas

Stephen Drummonds wrote:
Can anyone tell me about them?? Are they any better or worse than wire
antenna?? Thanks for any comments about this Steve




An active antenna can be a wonder. Compact size. Excellent gain.
Offers a lot of mounting choices. Uniform impedance across the spectra.

An active antenna can also be a PITA. Subject to overload.
Increased noise floor. Fragile connections. Susceptible to damage by
static.

Two things will determine whether an active antenna will be right
for you: 1) the quality of the active antenna. 2) the RF levels in
your listening area.

If you're not in a high RF zone...that is to say, if you don't
have local MW transmitters...you can get away with a relatively
inexpensive active while still enjoying decent performance. A poorly
designed active in a high RF area, will overload. Producing cross
modulation artifacts, and some stations will appear multiple
locations up and down the dial. You may also experience hum when a
strong clear signal is zeroed in.


A nearby lightning strike can wipe out an active in a stroke.

A random wire is not subject to overload. Although the front end
of your receiver may be. A random wire can be cut to size and
conditions. And will often have a lower noise floor at the input to
your receiver than an active. If you do overload your receiver, you
can always reduce the length of the wire.

A good active can cost you between $400 and $600 without
cracking a sweat. A good active will often require careful placement
to avoid man made noises. But this can be true of any antenna.

Are they better or worse? Neither. Each has its applications.
Each is superiour under specific conditions. You have to determine
if an active is right for you based on your own unique
circumstances, expectations.

My personal recommendation...start with a random wire, and see
how it works. Then experiment to determine if modifying your random
wire will get you where you want to go. Along the way, if an active
is a better choice, you'll see the clues.


I have one active which I take on the road with me. At the home
base, I use only passives.



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