Abstract: An electronically steered scanning active microwave reflector, capable of being illuminated by a microwave source to form an antenna, comprises a set of elementary cells, each comprising a phase-shifter microwave circuit placed before a conductive plane. This phase-shifter comprises conductive wires or tracks positioned on a support, the wires or tracks each comprising at least two two-state semiconductor elements, for example diodes, and being connected to conductors by which the states of the diodes can be controlled independently of each other, it being possible for each of the diodes to be on or off. Thus, four possible states are obtained and the geometrical and electrical characteristics of the cell are such that a given phase-shift value of the microwave received corresponds to each of these states. Finally, microwave decoupling means are provided between the cells. These means consist, in particular, of waveguides formed between two neighboring cells.

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: A microwave lens of the type described in the French patent No. 2,469,808 is adapted to operate with two crossed polarizations. To this end, each of the phase-shifting channels of the lens is subdivided into two subchannels, each of them being assigned to one of said polarizations. Each subchannel includes, in addition to phase-shifting panels, means for rotating by 90.degree. the polarization of the incident wave and impedance matching means.

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.

Abstract: This invention concerns a system to protect active or passive electronic equipment from radar detection. In other words equipment which transmits or receives microwave radiation, for example a radar or telecommunications transmitter or receiver.For this purpose, the transmitting surface of the equipment is covered by a device which can be controlled to apply a phase shift of approximately .pi./2 to the incident wave; this enables a microwave incident on the equipment to be modulated in phase. The frequency spectrum of the wave reflected by the equipment is modified and spread thus making it more difficult to detect the equipment. To avoid any perturbation of the operation of the equipment, an inverse modulation is applied to signals transmitted and/or received by the equipment itself.

Abstract: Disclosed is a source of microwave radiation, namely a source enabling the absorption of multiple reflections for the illuminating of a lens in order to form an electronic sweeping antenna. The source includes a layered arrangement of elementary illuminators in a direction substantially parallel to the electrical field of the microwave energy transmitted. In one embodiment, each elementary illuminator has the following successively, in the direction of propagation of the energy: a plane forming a short circuit; a plane forming an incidence filter, parallel to the above plane, located at a distance from the above plane of the order of half of a wavelength, including two tracks parallel to each other and perpendicular to the electrical field between which resistive elements are connected; and, a plane bearing a rdiating element of the snake line type, extending in a direction substantially normal to the electrical field.

Abstract: The invention pertains to a modulation method at pick-up of the amplitude of the secondary lobes of the radiation pattern for a hyperfrequency antenna and the method application for sensing and eliminating the jamming effects of jammers.According to the invention, we place as a filter (4) close to the reflector (1) which reflects the transmission-pick-up beam of the antenna, the filter having at least one network of conductive wires loaded with variable controllable resistors, such as diodes. During transmission, we make the filter (4) transparent by having strong equal currents travel through the wires, while at pick-up we modulate the amplitude of the currents traveling through the wires in order to obtain the desired distortions of the pattern.The invention especially applies to the sensing and elimination of the jamming effects produced by jammers.

Abstract: Process to attenuate or cancel certain side lobes of a microwave antenna pattern by using a network of parallel wires loaded with resistances that are adjustable at will, arranged as a filter in front of the antenna.Application of this process to the elimination of the effects of active or passive interferences, as well as to the localization of jammers.Adaptive filter for microwave antennas.

Abstract: A plurality of metallic wire conductors are fitted in shunt along a shorted wave guide parallel to a dielectric field of electromagnetic wave incident to the wave guide. At least some of the wires have diodes mounted on them such that selective biasing of the diodes renders these wires discontinuous and causes a controlled phase shift of the incident wave.

Abstract: Bipolar switches in first conductive leads mounted in a dielectric panel are divided into successive groups of alternating polarity and additional pairs of leads are positioned in the panel adjacent each first lead to couple the groups of switches in each first lead in parallel. A reduced reversed biasing of the additional leads results in the first leads being selectively rendered discontinuous by the switches, changing the electrical characteristics of the panel to shift or focus a microwave beam passing through the panel. The additional pairs of conductive leads also operate as microwave elements to increase the bandwidth of the panel.