DRAFT RADAR 900 Series Transponder Introduction The RADAR radio Transponder is the device at the metered of the RADAR system which allows readings to be obtained from water, gas and electricity meters from a distance by means of low-powered radio. ‘The Transponder enables meter readings to be taken from a distance via a hand-held system, using the RADAR hand-held Radii Reader, or by Radar's vehicle mounted system, or by Radar's fixed network product, the Microcode.