6: Antenna Systems
6-2 PRC1099A-MSOP
Ground Systems
End-fed whip or long wire antennas operate at maximum efficiency only
when used with a perfect ground system. In the manpack configuration the
ground is capacitively coupled through the operator’s body and almost all
output power is absorbed by the lossy ground system, the major reason for the
poor performance of HF manpacks. Even placing the transceiver directly on
the ground provides some improvement in efficiency. If possible, use a
separate ground system. Connect the transceiver ground terminal directly to
the ground using the shortest possible wire. The ground can be a ground stake
in moist soil or a water pipe going into the ground. A counterpoise system
using as many radial wires as possible improves performance even if there is
no direct connection to ground. A direct connection to a vehicle body provides
another effective counterpoise system. Even a single wire laid on the ground
or a connection to any mass of metal such as a wire fence improves
transceiver performance.
End-Fed Antennas
The end-fed antenna is usually erected as a vertical whip or long wire.
Connect the whip directly to the antenna terminal using a short connecting
lead. One end of the long wire antenna is connected to the antenna terminal.
The long wire can be erected part vertical and part horizontal, or in a sloping
configuration. Almost any support like trees or buildings work. Even
compromised installations where the antenna is draped over hedges or out of a
window can work and usually outperforms the manpack configuration. The
antenna does not have to be in a straight line. Keep the radiating part of the
antenna as high and in the clear as possible.
50 Ohm
Antennas
When adapters are removed from the antenna post, the antenna tuner is
disconnected and output is switched to the BNC antenna connector. Use any
50 ohm coaxial fed antenna with a VSWR of less than 3:1 (preferably 2:1)
with the PRC1099A.
Antenna Description
Resonant
Dipole
Simple, efficient antenna provides good long range coverage.
Length of antenna must be adjusted for frequency of use.
Broadband ABB100A and ABB100B offer good performance without
adjustment over 2 to 30 MHz frequency range.
Directional For long range communications. Rotatable arrays provide
coverage in all directions; fixed antennas for operation in
specific directions. Some are restricted to single frequency
operation; other arrays, such as log periodic, are used over a
wide frequency range.
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