Abstract: A microwave radar reflector includes three, substantially planar networks whose reflectivity or transmissivity may be controlled. The three networks are arranged as a trihedron with an open angle. An additional network, whose reflectivity or transmissivity may be separately controlled, is located at said open angle of the trihedron. With the additional network controlled to be transmissive and the other networks having their characteristic modulated between reflective and transmissive, the reflector will return a modulated message when the reflector is illuminated.

Abstract: The invention pertains to the sensing and elimination of jamming signals transmitted by jammers towards radar antennas. According to the invention, we associate with a main space surveillance radar antenna an auxiliary antenna that is outfitted with a modulating filter which enables the sensing of jammers, and the elimination of jamming effects by opposing, to the secondary lobes of the main antenna corresponding to the jamming directions, corresponding secondary lobes which are appropriately amplified by the auxiliary antenna. The invention applies to anti-jamming of radar antennas with mechanical or electronic sweeps.

Abstract: In a radar, a protective radome is placed in front of a to-be-protected antenna. The antenna is made of several networks that are superimposed. At least one of the active networks can be controlled electrically in two distinct states A or B. In state A, the radome, which is placed in front of the antenna, is transparent for the radar operation frequency band and reflective outside that band. For state B, the radome is reflective for all radar frequencies. The invention especially protects the radar against jammers that transmit outside the radar operation frequency band, while providing for the total camouflaging of the radar when it is not being used.