12
FT-90R OPERATING MANUAL
Antenna Considerations
The FT-90R is designed for use with antennas presenting an impedance of near 50
Ω at all operating frequencies. The antenna (or a 50 Ω dummy load) should be
connected whenever the transceiver is turned on, to avoid damage that could oth-
erwise result if transmission occurs accidentally without an antenna.
Ensure that your antenna is designed to handle 50 Watts of transmitter power.
Some magnetic-mount mobile antennas, designed for use with hand-held trans-
ceivers, may not be capable of this power level. Consult the antenna manufacturer’s
specification sheet for details.
Most all FM work is performed using vertical polarization. When installing a
directional antenna such as a Yagi or Quad, be certain to orient it so as to produce
vertical polarization, unless you are engaged in a special operating situation where
horizontal polarization is used.
Note that this transceiver is designed with wide frequency coverage in the VHF
and UHF spectra. For general listening, you may wish to have a broadband an-
tenna such as a discone available, because a directional antenna such as a Yagi
will have degraded performance outside the Amateur bands.
Excellent reference texts and computer software are available for the design and
optimization of VHF and UHF antennas. Your dealer should be able to assist you
with all aspects of your antenna installation requirements.
Use high-quality 50 Ω coaxial cable for the lead-in to your FT-90R transceiver.
All efforts at providing an efficient antenna system will be wasted if poor quality,
lossy coaxial cable is used. Losses in coaxial lines increase as the frequency in-
creases, so an 8-meter-long (25’) coaxial line with only ½ dB of loss at 28 MHz
may have a loss of 2 dB or more at 440 MHz; choose your coaxial cable carefully
based on the installation location (mobile vs. base) and the overall length of the
cable required (for very short runs of cable in a mobile installation, the smaller,
more flexible cable types may be acceptable).
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