18 Installing the Radio TM9100 Installation Guide
© Tait Electronics Limited August 2005
2.4 Installing the Antenna
This section provides information on installing an external antenna within 
the RF exposure limits.
Install the external antenna according to the antenna manufacturer’s 
instructions. Good quality 50Ω coaxial cable must be used, such as RG58 
or UR76.
Important Route the cable in a manner that minimizes:
■ coupling into the electronic control systems of 
the vehicle
■ coupling of electric vehicle systems, such as alternators, 
into the radio.
Avoid sharp bends in the cable. These distort the cable and 
alter its electrical characteristics.
Warning!! RF exposure hazard
To comply with FCC RF exposure limits:
1. Mount the antenna at a location such that no person or persons can 
come closer than 35 inches (0.9m) to the antenna.
2. For 40W/50W radios:
■ VHF radios must be installed using an antenna mounted centrally 
on the vehicle roof, with a gain of 2.15dBi or 5.15dBi.
■ UHF radios must be installed using an antenna mounted either 
centrally on the roof with a gain of 2.15dBi or 5.65dBi, or 
centrally mounted on the trunk with a gain of 5.65dBi.
3. For 25W radios, the radio must be installed using an externally 
mounted antenna with a gain of either 2.15dBi or 5.15dBi.
Terminating the 
Antenna Cable
1. Run the free end of the coaxial cable to the radio’s mounting position 
and cut it to length, allowing approximately 8 inches (20cm) excess 
at the radio end.
2. Terminate the free end of the antenna cable with the mini-UHF plug 
or BNC plug (supplied) as shown in Figure 2.4.
Figure 2.4 Terminating the antenna cable