User's Manual

800MHz & VHF Cell Enhancers

Maintenance Handbook

H/book Number:-50-078001HBKM

Issue No:-

Date:-02/09/2004

Page:-

59 of 88

5.12 2-Port RF Isolator (08-930002)

5.12.1 Description

The purpose of fitting an isolator to the output of a transmitter in a multi-transmitter

environment is such that each output is afforded a degree of isolation from every other. Were

this not to be the case, two simultaneous transmissions could interfere to create

intermodulation products, especially in the non-linear power amplifier output stages of the

transmitters. Whilst this effect would not affect the intelligibility of the two original

transmissions, a further two new transmissions would be created which could themselves

cause interference to third party users.

The ferrite isolator is a ferro-magnetic device, which has directional properties. In the

forward direction, RF arriving at the input is passed to the output with minimal attenuation.

In the reverse direction, RF arriving at the output due to reflected power from a badly

matched load, or due to coupling with another transmitter, is routed into an RF load where it

is absorbed. The isolator therefore functions to prevent reflected RF energy reaching the

power amplifier where it could cause intermodulation products or premature device failure.

5.12.2 Technical Specification

PARAMETER SPECIFICATION

Frequency range: 150-300MHz

Bandwidth (% of centre frequency): 2

Isolation: 35dB (typical)

Insertion loss: 0.25dB (typical

V.S.W.R: 1.15:1 (typical)

Maximum power: 200Watts (per carrier)

Connector: SMA

Weight: 200gm (approximately)