Operator's Manual

OM-E 2072-09689-00
3-3
3-3.3 Grounding
The resistance measured between the Micom-Z body and the system ground should be as small as
feasible. Failure to provide proper grounding will degrade system operation and cause RF voltage to
be present on the equipment chassis.
Wide copper straps, as short as possible, should be used for grounding. These straps should be
clamped or bonded to the vehicle body.
For vehicular installations, the vehicle body must be properly grounded during fixed station use. This
can be achieved by means of ground rods. Where the soil is dry and sandy, ground radials should be
used.
3-3.4 Vehicular Noise Reduction
Most vehicles contain several noise sources which can greatly disturb radio reception (for example,
the high voltage ignition sparks that are produced at the vehicle's plugs, and the alternator activity). If
necessary, install a noise reduction kit.
3-3.5 Antenna and Antenna Tuner Unit (ATU)
For fixed stations, dipole and broadband antennas, which provide a nominal impedance of 50 Ω, can
be used. In such applications, the antenna can be directly connected to the Micom-Z ANT connector.
For other applications, and in particular when using whip antennas, long wire antennas, and any
antenna which does not present a 50 Ω impedance over the full operating frequency range, an antenna
tuner unit (ATU) is necessary. Suitable ATUs, for example, F2265 and FLN2818, are available from
the manufacturer; these ATUs can be used in both mobile and base station applications. An externally
mounted mobile automatic antenna system, FAD1410, is also available.
The recommended vehicular whip antenna is FAD1400, also available from the manufacturer. To
achieve maximum operating range, the antenna should be mounted as high on the vehicle body as
possible without striking overhead obstructions in the normal service area of the vehicle. Select a
mounting location on a flat portion of the vehicle body, compatible with the maximum allowable
length of the ATU lead-in cable.
For short range communications (ground waves), a vertical (non-bent) antenna is preferred. For long
range communications (sky waves), a bent antenna is preferred. The antenna may be bent and tied
down to the vehicle's body with a nylon cord.
The best antenna location is the vehicle rooftop, where the antenna is not obstructed by metal objects.
Roof center installation provides good symmetrical omnidirectional radiation patterns. If roof top
installation is impossible, a side wall installation, with the antenna as far away from the side wall and
as high as possible, will suffice. If the antenna's height above ground is limited, it is preferred to install
the antenna as high as possible and to bend and strap it down to the required height (as opposed to
installing the antenna close to the ground, such as in a bumper mounted installation).
Suggested mobile installations are illustrated in Figure 3-2. Figure 3-3 shows options for installations
using FAD1410.