120 20110-142
Gemini
PD
Installation Guide
7
2.5 Antenna
To meet the FCC’s RF Exposure Guidelines,
the main transmitter antenna must be vehicle-
mounted to provide a separation distance of
50 cm or more from all persons and the
an-
tenna gain
must not exceed 5dB to satisfy
RF exposure requirements.
2.5.1 Recommended tools and
supplies
•
circle cutter
•
hole saw or
•
socket punch for antenna
•
Mini-UHF Crimp tool
2.5.2 Planning
Referring to Figure 4, Gemini
PD
commonly
uses three separate antennas:
•
“T” - Main transceiver -
Constraints are Maximum Permissive
Exposure (“MPE” on the drawing) limits
of 50 cm (as per see section 2.5 above)
and omni-directional factors
•
“R” - Auxiliary receiver –
Constraints are the receiver spacing of at
least 5/8
λ
(wavelength) from trans-
ceiver antenna and omni-directional re-
quirements
•
“G” - Global Positioning System (GPS)*
Constraints are TX spacing of at least
24-in/60.96 cm from all transmitting an-
tennas and a clear view of the sky.
For the optimum antenna spacing at the fre-
quency you are using, consult System Engi-
neering.
For installation of ground-plane dependent
antennas, the center of the metal surface
used for mounting is preferable for best
omni-directional pattern.
For ground-plane independent antennas, in-
stallation may be close to the edges of the
surface.
*
The
Gemini
PD
Lite model has no GPS.
Figure 4 - Antenna spacing
Install the antennas in one of the following
positions:
-
Most preferred for all antennas: center-
line of roof. For transmitter antenna, it is
the ONLY acceptable position.
-
Less preferred for receiver antenna:
trunk lid, providing distance to transmit-
ting antenna is respected whether lid is
opened or closed.
-
Much less preferred, but permissible for
receiver antenna: left or right rear fend-
ers, just in back of rear window
-
Least preferred, but permissible for re-
ceiver antenna: left or right front fenders,
ahead of windshield
Note:
Proximity to other vehicle-mounted
antennas may cause mutual inter-
ference especially at higher fre-
quencies.
G
MPE
≥≥≥≥
5/8
λλλλ
(UHF: 18"/46cm
800MHz: 9"/23cm)
R
T
50cm
19.7in.
≥≥≥≥
24in.
