Antenna for primary and secondary radars

In a radar system for the monitoring of air traffic, including a primary-radar transceiver, a secondary-radar transceiver, a reflector, a primary feeder confronting said reflector and comprising in succession a rectangular waveguide connected to the primary-radar transceiver for carrying high-frequency wave energy therebetween, a matching waveguide, a circular waveguide with a cylindrical section, and a rectangular horn extending from said circular waveguide toward said reflector, two probes arranged at diametrically opposite locations in said cylindrical section, said probes having a common axis which includes an angle of not more than about 45.degree. with the planes of the major sides of the rectangular horn, said probes being connected to the secondary-radar transceiver for exchanging interrogation signals therewith, two ancillary feeders facing said reflector in symmetrical positions on opposite sides of the rectangular horn, and a power divider inserted between the secondary-radar transceiver and said ancillary feeders for supplying same with phase-opposed control signals to be radiated toward said reflector for transmission to an aircraft along with said interrogation signals,

• the combination therewith of a monopulse channel carrying incoming signals from transponders aboard the interrogated aircraft, said monopulse channel including a pair of auxiliary sources flanking said horn and confronting said reflector in a common azimuthal plane with said ancillary feeders, and angular-deviation-measuring means with inputs connected to said auxiliary sources and to said probes for respectively receiving therefrom a difference signal and a sum signal of said monopulse channel.