Ericsson ORION, Installation Manual

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Figure 6 - Radio Installation, Kawasaki K1000
(188D6803, Sh. 2, Rev. 2A)
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ANTENNA INSTALLATION
General
The Ericsson ORION motorcycle options for the VHF, UHF, 800 MHz,
and 900 MHz land mobile radio bands were specifically designed for use with
Larsen OM series antennas. With the OM series antenna a ground plane is no
longer necessary. The OM series antenna is an end fed high impedance antenna
which provides the proper VSWR and radiation pattern without the use of a
ground plane. Typical antenna gain without a ground plane is 0 dB. If a ground
plane were to be used, the antenna gain will increase by 2.4 dB.
The case/antenna mounting plate (188D6437P1) was specifically
designed to fit the hole mounting pattern for the OM series mount.
To properly use a thru-line wattmeter one of the following two conditions
must be met:
•
If the wattmeter is installed right at the ORION’s RF port and the odd
multiple of a quarter-wavelength of coax to the antenna is used, correct
readings will result. Any other length of coax will result in improper
readings.
•
If a length of coax equal to a multiple of a half-wave length is installed
between the ORION’s RF port and the thru-line wattmeter and an odd
multiple of a quarter-wavelength of coax to the antenna is used, correct
readings will also result. Any other length of coax will result in improper
readings.
To calculate the proper cable length of the antenna coaxial cable, proceed
as follows:
1. Determine the center frequency of the majority of programmed transmit
channel frequencies.
Since the Larsen OM series antenna is a high impedance, voltage fed
antenna, the length of the coaxial cable from the antenna to the ORION’s
RF port is critical. It cannot be just any arbitrary length. To prevent possible
extraneous radiation, RFI feedback from the antenna to the radio, high
VSWR, and antenna ground currents, select an antenna coaxial cable
length that is close to a multiple of an odd quarter-wavelength.
CAUTION
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