Abstract: A microwave radiating element including first and second means for conveying electromagnetic waves in respective first and second frequency bands, wherein the first and second means are coaxial.

Abstract: The invention relates to a receive (or send) antenna for a geosynchronous satellite of a telecommunications system intended to cover a territory divided into areas, the beam intended for each area being defined by a plurality of radiating elements, or sources, disposed in the vicinity of the focal plane of a reflector. The antenna includes at least one first matrix each input of which is connected to a radiating element and each output (or input) of which is connected to a corresponding input of an inverse Butler matrix by an amplifier and a phase-shifter. The phase-shifters move the areas or correct pointing errors.

Abstract: A terminal and antenna system (1, 10) for transmitting and receiving radio signals to and from satellites (2, 3) chosen from a constellation of non-geostationary satellites, including means for determining the position of the satellites visible from the terminal and antenna system, means for focusing quasi-plane waves received from or transmitted to a chosen visible satellite towards a focal surface S, primary sources (23, 24) for transmitting and receiving signals in the form of quasi-spherical wave beams, mobile independently over the sphere S in a manner that is slaved to the particular position of the non-geostationary satellites.

Abstract: The invention concerns a multilayer focusing spherical lens (21) adapted to be mounted in a transceive antenna device (1) of a terminal of a remote transceiver system and having a concentric focal sphere (S), the lens including a central layer (21a) and a peripheral layer (21b) having different dielectric constants, each dielectric constant value being determined so that the lens (21) focuses parallel microwave beams towards the focal sphere (S) concentric with the lens. A transceive antenna includes a lens of the above kind and a terminal for transmitting and receiving radio signals to and from at least two remote transceiver systems moving at different points in the field of view of the terminal, said terminal including an antenna of the above kind. The invention applies in particular to systems for transmitting data at high bit rates to and from a constellation of satellites, for public or private, civil or military use.

Abstract: The invention relates to a device for transmitting and receiving microwaves including a planar radiating element. The device is characterized in that the radiating element (60) has substantially orthogonal transmit and receive ports (68, 66) and the relative phase of the transmit and receive signals and the shape of the radiating element are such that the transmit and receive signals, whose frequencies are different, are circularly polarized in opposite directions.

Abstract: A transmission relay system includes a receive antenna with first radiating elements, a transmit antenna with second radiating elements, and processing devices through which the first radiating elements and the second radiating elements are connected. The processing devices are in the form of processing systems all of which induce the same propagation time-delay. Each system connects a given first radiating element to a corresponding given second radiating element defined firstly by an angular position relative to a second axis of symmetry specific to the transmit antenna offset substantially 180.degree. relative to an angular position of the given first radiating element relative to a first axis of symmetry specific to the receive antenna and parallel to the second axis of symmetry and secondly by an eccentricity in the transmit antenna which is a function of an eccentricity of the given first radiating element in the receive antenna.

Abstract: The invention concerns a microwave transmit/receive (T/R) circuit for a polarization synthesizer array antenna, especially a radar antenna. According to the invention the required polarization is obtained by applying two signals to an array element on two orthogonal feed paths with a variable phase difference between the two paths, both of which function simultaneously. In a preferred embodiment both transmit channels are provided with two power amplifiers which each amplify a signal from an in-phase power divider or a hybrid coupler, with a one-bit or two-bit controllable phase-shifter adding a phase-shift of 0.degree., 90.degree. or 180.degree. to synthesize orthogonal linear or circular polarizations. In a preferred embodiment the circuit according to the invention is partly or entirely implemented in monolithic (MMIC) technology. The invention also concerns an antenna including a T/R circuit as specified hereinabove.

Abstract: An electronically-scanned two-beam antenna designed for being installed on board a moving platform, and in particular a satellite. The antenna of the invention comprises a single, complex reflector whose reflectivity is responsive to the polarization with which it is illuminated, and associated with two arrays of orthogonally-polarized sources that illuminate the complex reflector using an offset configuration. The complex reflector is made up of two reflectors placed one in front of the other in the beam propagation direction. The first reflector is transparent to a first linear polarization and reflective to an orthogonal polarization, while the second reflector is reflective at least for the first polarization. The two resulting beams thus propagate in different directions, both parallel to the trajectory of the platform. Electronic scanning is provided in a plane perpendicular to the orbit plane.

Abstract: In a method of calibrating an active antenna the active elements of a transfer function matrix are measured using a near field probe for each radiating source of the antenna. The probe is placed in front of each source in succession and each source is excited in turn with the opposite phase and with all the other sources of the array excited normally. In the case of linear superposition of radiated fields, the measurements obtained by this method yield the elements of the transfer function matrix directly. This allows for phase and amplitude errors due to the components of the active antenna and for the effects of coupling between adjacent sources which modify the theoretical characteristics of the antenna. In the non-linear case the measurements are repeated and the matrix is obtained by iteration based on a comparison of the theoretical values used to control the antenna and the measured fields actually obtained.

Abstract: A microwave array antenna comprises a plurality of like unit sources whose width increases progressively from the center of the array towards its ends and which are disposed relative to each other in such a way that substantially no illumination gaps are created in the array.

Abstract: A high-efficiency active printed-circuit antenna system for pulsed frequency-hopping space radar electronically scanned in two planes encompasses in its timing diagram the transmission of a horizontal polarization pulse, the reception of echoes from a previous horizontal polarization pulse, the transmission of a vertical polarization pulse and the reception of echoes from a previous vertical polarization pulse. The system comprises several thousand MMIC modules distributed over the antenna and each connected to a printed-circuit radiating element comprising a plurality of dual polarized square patches connected by microstrip lines which excite them with the same amplitude and the same phase at two perpendicular ports. Switching between the two ports procures transmission or reception with horizontal or vertical polarization.

Abstract: A method of forming the radiation pattern of a high efficiency active antenna for electronically-scanned radar, wherein its illumination laws, and thus its radiation patterns are dissociated in transmission and in reception; and equal amplitude illumination is provided in transmission in order to maximize the efficiency of the transmit amplifiers which are all identical, thereby minimizing their DC energy consumption and their dissipation. The invention is particularly suitable for use in space radars.