TETRA Antenna Combiner
Radio Systems Information Ltd.
Page 4
1
Introduction
1.1
General
The TETRA Antenna Combiner is designed to work with the Gemini survey tool allowing up to
four TETRA class 3 (3W) radio terminals to be connected to a single antenna whilst meeting all
ETSI requirements for isolation between radio terminals so that each may be operated
independently with no degradation in performance caused by the other terminals.
The TETRA Antenna Combiner is available in two models:
Model A – with utra-linear power amplifier allowing 2 of the 4 TETRA terminals to be combined
with 0dB loss in the transmit path. The remaining 2 terminals have 11dB loss in the transmit
path.
Model B – passive design with all terminals having 11dB loss in the transmit path.
Note that 11dB is the difference (as proposed by PITO) normally applied to degrade a vehicle
antenna to give the same performance as the antenna on a body-worn handportable radio
terminal.
The Model A contains a front panel mounted fan for forced air cooling of the RF power amplifier
with the vent being on the side of the case. Both the front and the side of the case must
therefore not be obstructed.
Both models include individual switches for each terminal to include a further 5dB loss in the
transmit path to simulate the difference in transmit power level between a class 3 (3W) vehicle
radio and a class 4 (1W) hand-held radio.
