Abstract: A reflector of an antenna in a radar system subject to jamming carries a multiplicity of localized phase shifters which are sequentially controlled by a processor to introduce certain phase modifications into incoming signals reflected toward an associated radiator. The processor, operating on branched-off portions of the incoming signals, compares the magnitudes of the signals received in the several operational states of each phase shifter and maintains that operational state for which the signal level is at a minimum. The comparisons may be carried out on signals received at the end of a signal-transmission cycle, lacking a useful component.

Abstract: There is described an electronic scanning antenna comprising a multiplicity of elementary radiators arranged for example in a vertical plane and constituting an array designed for simultaneous surveillance and tracking, the array being fed by two parallel waveguides. The first waveguide is connected to the radiators through a set of first couplers in cascade with a set of fixed phase shifters. The second waveguide is connected to the radiators through a set of second couplers in cascade with a set of variable phase shifters and with the first couplers and the fixed phase shifters. The waveguides are connected to respective transmitters and receivers operating at different frequencies. The complete assembly produces simultaneously at least one tracking beam which varies in elevation and one searching beam having a fixed, preferably low elevation angle.

Abstract: In order to compensate for the displacement of a coherent pulse airborne radar, the latter is provided with means for alternately linearly moving forward and backward the phase centre of its antenna system, at the reception, from one cycle radar to the next.The displacement of the phase centre is carried out by introducing a controllable dissymmetry in the illumination of the linear radiating aperture of the antenna system.