IMPROVEMENTS IN OR RELATING TO SECONDARY SURVEILLANCE RADAR

摘要

A secondary surveillance radar is provided with means for reducing the effect of undesirable reflections on the interrogation pulses transmitted by the radar and the replies received in response to the interrogations. In addition to a directional antenna a further omni-directional antenna is provided and the energy of certain of the interrogation pulses are shared between the two antennas in such a manner as to enhance suppression of replies from aircraft which are located at angles away from the boresight of the directional antenna.