Installation Manual

Table Of Contents
Connection of the Combiner Assembly 101
Release 3.3, Revision A 1/99
Appendix 1
Connection of the Combiner Assembly
A1-1 Introduction
The combiner assembly kit is intended to enable a single antenna to serve two TRXs in one of the following
configurations:
1
Transmitter signals from two power amplifiers may be combined to drive a single antenna.
2
The receive band from a single antenna may be split to serve two separate base stations at different loca-
tions.
3
Antenna ports Ant1 and Ant2 on the BTS RF distribution card may be combined to use a single antenna in
both receive and transmit mode to serve two different TRXs operating on different channels.
A performance penalty is experienced in all three of these applications because the division of power by two results in
a 3dB loss in both directions of operation (to which must be added the internal losses of the coupler, approximately
1dB, for a total of 4dB). The receiver sensitivity will be impaired by this amount, while the transmitted power will be
reduced by this amount.
The combiner assembly can be used for a two-TRX BTS. In this configuration, the combiner assembly is used to
combine the outputs of the two power amplifiers into a single feed. This allows a two-TRX BTS to operate with a single
antenna for both transmission and reception. This configuration offers full receiver sensitivity for each of two channels,
but reduced power output by 4dB in each channel, and no capability for receiver diversity.
The combiner assembly can also be used for a three TRX BTS, in which the third transmitter output is combined with
one of the others to feed an existing antenna. In this case, two duplexed antennas offer full receive sensitivity for all
three channels, switched antenna receive diversity for all three channels, full transmitter power on TRX No.1, and 4dB
reduced tranmsitter power on TRX No. 2 and No.3.
Two combiner kits are available:
Part number M640104 is used for 900MHz BTSs
Part number M640133 is used for 1800MHz BTSs