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AR3030 operating manual
with about 3 controls on the front. The disadvantage is the need to constantly
re-tune the ATU when changing frequency. An ATU of this nature is "passive",
this means that no power is required to operate the ATU and no extra circuit-
noise is introduced into the receiver.
Loop Aerials
Desk-top loop aerials have the advantage of small size (such as the AOR
LA320). They too have tuning controls to reject unwanted signals. As the
loop is within easy reach of the operator it can be rotated to provide directivity.
They can be particularly useful for DX'ing the lower bands.
Generally speaking they offer excellent portability but cannot compare on the
higher bands with a well sighted long wire aerial.
Active aerials
Active aerials are normally quite compact (AOR WA7000) and combine a wide
coverage aerial with a preamplifier mounted within the aerial its-self. They
require power to enable them to operate. Not all designs allow you to switch
the preamplifier off although some have a gain control.
As with loop aerials they tend to provide good results on the lower bands when
compared to poorly sighted short'ish wire aerials. Overload can be a problem
on the busy 7 and 9 MHz bands. If you have a small garden space, an active
aerial may be worth considering.
Discone
For wide coverage in the VHF-UHF bands a compromise has to be met and the
most popular aerial is a discone (AOR DA3000). Their appearance is like a
large spider or umbrella without the covering material, the better models have
about 16 elements.
50
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