Abstract: A periodic electromagnetic medium is disclosed that includes a surface that provides an interface with an ambient medium and a periodic structure that provides negative refraction within the medium of an incident electromagnetic field incident on the surface. In various embodiments the incident electromagnetic field is within a range of frequencies, the medium may include dielectric or metallic material, and has either a positive or negative effective index.

Abstract: An improved plasma controlled millimeter wave (MMW) or microwave (&mgr;W) antenna is provided. A plasma of electrons and holes is photo-injected into a photoconducting wafer. A special distribution of plasma and a MMW/&mgr;W reflecting surface behind the wafer allows the antenna to be generated at low light intensities and a 180° phase shift (modulo 360°) to be applied to selected MMWs/&mgr;Ws.

Abstract: An apparatus and method for aligning the antennas of two transceivers of a point-to-point wireless millimeter wave communications link. A narrow band oscillator power source is substituted for the signal transmitting electronics associated with a first antenna and a power detector is substituted for the signal receiving electronics associated with a second antenna. In preferred embodiments after a first alignment procedure is performed, the procedure is repeated with an oscillator power source connected to the second antenna and a power detector connected to the first antenna. In other preferred embodiments the antennas are pre-aligned using a signaling mirror or a narrow beam search light or laser. After the antennas are aligned the transceiver electronics are reconnected. In preferred embodiments the communication link operates within the 92 to 95 GHz portion of the millimeter spectrum and provides data transmission rates in excess of 155 Mbps.

Abstract: A reconfigurable adaptive wideband antenna includes a reconfigurable conductive substrate for dynamic reconfigurablility of the frequency, polarization, bandwidth, number of beams and their spatial directions, and the shape of the radiation pattern. The antenna is configured as a reflect array antenna having a single broadband feed. Reflective elements are electronically painted on the reconfigurable conductive surface using plasma injection of carriers in high-resistivity semiconductors.

Abstract: An artificial magnetic conductor is resonant at multiple resonance frequencies. The artificial magnetic conductor is characterized by an effective media model which includes a first layer and a second layer. Each layer has a layer tensor permittivity and a layer tensor permeability having non-zero elements on the main tensor diagonal only.

Abstract: Equipment and methods for aligning the antennas of two transceivers of a point-to-point wireless millimeter wave communications link and keeping them aligned. Each of two communicating antennas is equipped with a telescopic camera connected to a processor programmed to recognize landscape images. The processors are programmed to remember the pattern of the landscape as it appears when the antennas are aligned. Each of the cameras then view the landscape periodically or continuously and if the landscape in view changes by more than a predetermined amount a signal is provided to indicate a misalignment. An operator can then take corrective action or alternatively the antenna system can be configured for remote or automatic realignment based of feedback from the camera.

Abstract: An antenna apparatus such that a dielectric strip and a dielectric resonator are provided to form a primary vertical radiator, another dielectric strip is provided which is coupled to the dielectric strip to form a directional coupler, and a radiation beam is tilted by changing the relative position of the primary radiator with respect to the dielectric lens by displacing the primary vertical radiator in the directional coupler.

Abstract: A wave-scanning antenna is disclosed that does not require a rotary joint. The antenna produces a collimated beam that can be scanned through 360 degrees. The beam is directed perpendicular to the antenna's axis of rotation to form a disc-like surveillance volume, or at an angle above or below the perpendicular to form a cone-shaped surveillance volume. The radar's structure contains a transmitter and receiver coupled to a horn protruding through open centers of the support bearing and driven gear into the antenna housing. Energy emitted by the horn proceeds upward until deflected through an angle of 90 degrees by an angled reflector located on the axis of rotation. The energy is collected by a dielectric lens and focused into a collimated beam. Reflected energy is collected by the lens and directed by the reflector to the horn, where it is fed to a waveguide coupled to the receiver.

Abstract: A tuneable impedance surface for steering and/or focusing a radio frequency beam. The tunable surface comprises a ground plane; a plurality of elements disposed a distance from the ground plane, the distance being less than a wavelength of the radio frequency beam; and a capacitor arrangement for controllably varying the capacitance of adjacent top plates, the capacitor arrangement including a dielectric material which locally changes its dielectric constant in response to an external stimulus.

Abstract: DC inductive FSS technology is a printed slow wave structure usable for reduced size resonators in antenna and filter applications of wireless applications. It is a dispersive surface defined in terms of its parallel LC equivalent circuit that enhances the inductance and capacitance of the equivalent circuit to obtain a pole frequency as low as 300 MHz. The effective sheet impedance model has a resonant pole whose free-space wavelength can be greater than 10 times the FSS period. A conductor-backed DCL FSS can create a DC inductive artificial magnetic conductor (DCL AMC), high-impedance surface with resonant frequencies as low as 2 GHz. Lorentz poles introduced into the DCL FSS create multi-resonant DCL AMCs. Antennas fabricated from DCL FSS materials include single-band elements such as a bent-wire monopole on the DCL AMC and multi-band (dual and triple) shorted patches, similar to PIFAs with the patch/lid being a DCL FSS.

Abstract: A constrained feed can enable a phased array to be fed from a number of subarray ports while maintaining good sidelobe control. The invention pertains to using constrained feed networks, like Rotman lenses, Butler matrices and waveguide networks instead of a single space feed, to produce these subarrays. The formed subarrays are partially overlapped, and this is required to develop good sidelobe control. The invention solves the problem of having high sidelobes when an array is fed by contiguous, uniformly illuminated subarrays and so allows optical time delay, digital time delay and limited field of view scanning with a constrained network while maintaining low sidelobe radiation.

Abstract: A steerable antenna and method of steering a radio frequency wave received by and/or transmitted from the antenna. The antenna includes a tunable high impedance surface and at least one end-fire antenna disposed on said surface. The method includes varying the impedance of the tunable high impedance surface.

Abstract: A direction-agile antenna system is implemented in a wireless network to allow wireless communication devices to establish and maintain wireless data links with each other.

Abstract: A tuneable impedance surface for steering and/or focusing a radio frequency beam. The tunable surface comprises a ground plane; a first plurality of elements disposed in an array a first distance from the ground plane, the distance being less than a wavelength of the radio frequency beam; and a second plurality of elements disposed in an array a second distance from the ground plane, the second plurality of elements be moveable relative to the first plurality of elements.

Abstract: An improved phased array antenna having a low profile is disclosed. The antenna has a polarizer and a rotating phased array. MEMS phase shifters are used for electronically controlling relative phase shift between antenna elements and MEMS switches employed to provide beam steering and polarization switching.

Abstract: A radar apparatus has an inclined slot wave guide array to form a narrow azimuth beam and a dielectric lens in front of the array to form a narrow elevation beam. The radar apparatus is particularly useful for motor vehicular collision warning systems. The inclined slot wave guide forms an antenna which is driven to oscillate back and forth at a small angle. The dielectric lens is fixed in position relative to the slotted wave guide antenna. The combination of the slotted array for forming a narrow horizontal pattern in combination with the dielectric lens for forming a vertical pattern provides an arrangement that is readily scannable.

Abstract: A motor-drive device for sensors around a spherical electromagnetic lens, for example a Luneberg type lens using in a system of transmission and/or reception, comprises, for each module, at least one piezoelectric motor rigidly connected to the module, the module moving in the vicinity of the surface of the lens by the reptation of the piezoelectric motor on this surface. The disclosed device can be applied especially to receivers and/or transmitters carrying out multiple-satellite tracking, for example in the field of communications by orbiting satellites.

Abstract: A beam forming low profile scanning antenna system is provided comprising a radiating element (11) for radiating signals and a pair of panels (13 and 15) each having an array of phase-inducing transmitting resonant elements (21) on a pair of panels for focusing said radiating signals to produce radiated beams. The panels are rotated with respect to each other (17) to scan said beams.

Abstract: An improved plasma controlled millimeter wave (MMW) or microwave (&mgr;W) antenna is provided. A plasma of electrons and holes is photo-injected into a photoconducting wafer. A special distribution of plasma and a MMW/&mgr;W reflecting surface behind the wafer allows the antenna to be generated at low light intensities and a 180° phase shift (modulo 360°) to be applied to selected MMWs/&mgr;Ws.

Abstract: A circularly polarized reflect array antenna having a plurality of antenna elements, where each antenna element has an electrically conductive patch, at least two electrically conductive stubs positioned along the periphery of the patch, and at least two switches each operable to connect or disconnect the patch to one of the at least two stubs.

Abstract: A dual-band electronic scanning antenna, with an active microwave reflector. The antenna includes at least two microwave sources transmitting in different frequency bands and having opposite circular polarizations. An active reflecting array including elementary cells illuminated by the sources is provided. A polarization rotator is inserted between the reflecting array and the sources, changing the circular polarizations into two crossed linear polarizations. An elementary cell includes a conducting plane and first and second transverse phase shifters, the first phase shifter is substantially parallel to a linear polarization and the second phase shifter is substantially parallel to the other linear polarization. The conducting plane is placed substantially parallel to the phase shifters. The antenna is applicable in particular for microwave applications requiring two transmission bands moreover subject to very low-cost production conditions.

Abstract: A directionality switching antenna apparatus of the present invention is provided with radiator 102 in folded form, folded at a length of predetermined length from a feeding point of ground plane 101, with one end thereof connected to the feeding and with the other end thereof shorted with ground plane 101, a plurality of parasitic elements 103 spaced in the vicinity of radiator 102 each with an element length set to provide the parasitic elements with an electrically symmetrical relation to the center axis of radiator 102, inductors 104 loaded on respective parasitic elements 103, diodes 105 connected to ground plane 101, switching elements 106 that connects in parallel respective inductors 104 and respective diodes 105 between respective parasitic elements 103 and ground plane 101.

Abstract: A microwave phase-shifter including a coupler in a waveguide form, at least one pair of phase-shifter cells, and a conductive strip positioned between each phase shifter cell and configured with a conductive plane to form a guided space where a wave cannot propagate. An incident wave entering a first input of the coupler is subdivided into two waves. Each of the waves are reflected on an elementary cell with identical phases to the incident wave and are recombined into a resultant phase-shifted wave prior to exiting the coupler by an output juxtaposed with the first input.

Abstract: A dual polarized single axis scanned phased array antenna includes a predetermined number of mutually adjacent radiating columns which generate respective beams scannable in azimuth while providing a fixed beam in elevation, and wherein each radiating column utilizes a low loss dielectric slab assembly to serve multiple functions. The slab assembly serves, among other things, as a lens to correct the spherical wave from a small feed to a plain wave within a column. The slab assembly also includes a septum polarizer necessary to carry both horizontally and vertically polarized fields. The slab assembly additionally includes a dielectric radiator element to provide a radiating surface without the need to form a ground plane. The dielectric slab assembly, moreover, inherently loads the radiating columns so that they can be spaced one half of a free space wavelength without cutting off the vertically polarized fields.

Abstract: A wideband matching surface (600) for a dielectric lens antenna (100) is formed from a first dielectric layer (602) (e.g., Rexolite™) characterized by a first refractive index and a second dielectric layer (604) characterized by a second refractive index supporting the first dielectric layer (602).

Abstract: At least one electromagnetic lens having a first contour is disposed proximate to a dielectric substrate having a first edge having a second contour. A plurality of antenna feed elements, for example, end-fire antennas, are disposed on the dielectric substrate along the second contour. A signal applied to a corporate feed port is switched to the antenna feed elements by a switching network, wherein each antenna feed element launches an electromagnetic wave that is diffracted by the at least one electromagnetic lens so as to form an associated beam of electromagnetic energy. Different antenna feed elements generate different beams of electromagnetic energy in different directions. A pair of electromagnetic lenses with associated antenna feed elements at different edge locations on the dielectric substrate provide for bi-static operation. A reflector may be used to redirect the beams of electromagnetic energy.

Abstract: A device for generating and radiating pulses of radio frequency/microwave energy in response to pulses of laser light in which a metal layer is ohmically bonded to each side of a substrate of semiconductior material and an antenna bowtie pattern is ohmically bonded to the metal layers to form a feed structure for a Luneburg lens type antenna. There is at least one aperture available on the substrate of the semiconductor material for permitting laser light to reach the disk to produce photoconduction. The photoconductive switch is electrically connected to the storage device to facilitate fast discharge of the stored energy through the switch. The feed structure is mounted on a motorized support stand, which is connected to a center post by an arm that can rotate 360° in the azimuthal direction and ±90° in elevation. The feed structure is located on the outermost shell of the Luneburg lens, and is concave to conform to the focal radius of curvature of the outermost shell.

Abstract: An antenna system and method for transmitting or receiving a plurality of pixel beams of satellite communication signals. A focusing device (770) focuses pixel beams on individual antenna elements or horns (708 or 808) of the transmitter (700) or receiver (800). In the transmitter, each antenna element transmits a pixel beam, and in the receiver, each antenna element has focused on it an individual pixel beam.

Abstract: A method and a device is disclosed for the generation of a lens device including a plate of ferroelectric material, the transmission phase gradient of which is be varied over the lens by means of a controllable static electric field. The division of an aperture will depend on the number of degrees of freedom to be controlled simultaneously. According to the present invention an electromagnetically transparent highly resistive film (24, 34) is applied at both sides of a plate presenting ferroelectric properties. At two opposite edges of these resistive films highly conducting wires (22, 23 and 32, 33) are applied and electrically connected along the resistive film. The pairs of highly conductive wires at the opposite edges of each one of the two films on the plate presenting the ferroelectric properties are running perpendicular to each other.

Abstract: A layered, electronically scanned antenna. The antenna includes a plurality or array layers separated by dielectric spacers. Each array layer includes a transistor switched grid formed by a plurality of reflective/transmissive elements such as cross dipoles interconnected by a plurality of semiconductors, such as MOSFETs. When the switched grid is in an open state, its associated array layer is reflective. When it is in a closed condition, its associated layer is in a transmissive state. By controlling the state of each array layer, a desired degree of phase shift can be imparted to the signal reflected by the antenna. The antenna thus eliminates the need for costly MEMS/MMIC technology to achieve the desired degrees of phase shift of a signal reflected by the antenna.

Abstract: An antenna comprising a feed for delivering electromagnetic energy to a rotatable combination of a dielectric lens and a reflective surface. The combination of the dielectric lens and the reflective surface is placed proximate to and in front of an energy feed, such as a horn, to support the scanning of an antenna beam in response to rotation of the lens/reflective surface assembly. The lens typically comprises a dielectric material and the reflective surface can comprise a thin layer of material operable to reflect electromagnetic energy. For example, the lens can comprise a half-cylinder shape of dielectric material and the reflective surface can be applied to the flat portion of the half-cylindrical lens. Alternatively, the antenna can comprise two or more electromagnetic feeds and a cylindrical lens of dielectric material including a centrally-embedded, two-sided reflective surface.

Abstract: A multiple band reconfigurable reflecting antenna array and method for multiple band operation and beam steering. An array of dipole antennas is disposed on a multiple band high impedance surface. The antenna array is reconfigured by changing the length of the dipole elements, to thereby change the dipoles resonant frequency. At a given frequency band, small changes in dipole length allow to steer the reflected beam in the selected direction; whether large changes in dipole length permit to switch the operating frequency band. A method of broadening the bandwidth of a high impedance surface is also exposed.

Abstract: A foaming material is charged between a spherical lens and a radome, to form a foaming material layer, thereby to connect the both and support the spherical lens from the side of the radome, in order to provide an easily manufacturing and assembling method having excellent electrical properties, when providing an antenna capable of tracking a plurality of communication satellites and being installed in compact in a relatively small space. The foaming material layer is set at the same dielectric constant as that of the spherical lens or lower than that. Since the radome supports the spherical lens, any special supporting instrument is not necessary. Electrical deterioration occurs to the radome only, not to the supporting instrument. Generally, the radome is little affected by the electrical deterioration and the permeability of the electric waves is uniform, the permeable electric waves are hardly affected.

Abstract: An antenna apparatus such that a dielectric strip and a dielectric resonator are provided to form a primary vertical radiator, another dielectric strip is provided which is coupled to the dielectric strip to form a directional coupler, and a radiation beam is tilted by changing the relative position of the primary radiator with respect to the dielectric lens by displacing the primary vertical radiator in the directional coupler.

Abstract: An antenna array for a base station for communication systems presenting a sparse element grid in a one-dimensional scanned array or multi-beam array is presented. The element spacing is primarily governed by scanning in a horizontal direction. In a triangular element grid the individual element spacing in a vertical direction is increased to an order of a wavelength (dy≈&lgr;) without generating grating lobes in visible space for the obtained main lobe, and maintaining about half a wavelength spacing in a horizontal direction (dx≈0.48&lgr;). This results in a reduction of radiating elements compared to a square grid of radiating elements arranged with a spacing of half a wavelength. By taking into account and limiting the horizontal scan, the vertical spacing may be further increased (dy≈1.25&lgr;−2&lgr;) to obtain an optimum sparse antenna element grid for a one-dimensional scanned beam or a multi-beam pattern e.g., for a communication system base station.

Abstract: An antenna includes first and second arrays spaced apart by a dielectric slab having a predetermined thickness, each of the first and second arrays provided from antenna elements having a linear polarization with the antenna elements in said first array disposed orthogonally to the antenna elements in said second array. The antenna further includes a feed circuit coupled to said first and second antenna arrays to provide said first and second antenna arrays having a phase relationship such that the antenna receives and transmits signals having circular polarization and dielectric material having differing characteristics for providing an impedance transformation that varies with scan angle in accordance with the a scan impedance of said antenna thereby providing the antenna having a scan impedance which is substantially the same over a scan sector while at the same time preserving the response characteristic of the antenna to signals having circular polarization.

Abstract: A satellite communication antenna apparatus for performing communication with a communication satellite, comprises a spherical radio wave lens, an arcuate guide unit arranged along an outer surface of the radio wave lens and having a central point common with the radio wave lens, an antenna unit reciprocally movable along the guide unit, and an antenna positioning unit for positioning the antenna unit, wherein the guide unit is made of a material with a low specific dielectric constant.

Abstract: A method and a device are disclosed for the generation of a surface, the reflection phase gradient of which will be varied by means of a controllable static electric field. The present solution takes into account, instead of mainly the transmissive properties, also the reflection properties of an arrangement comprising a ferroelectric material. Such a reflecting surface may contribute to an entire antenna aperture, a portion of an antenna aperture or an element in a conventional array aperture. In a general case N lobes and M nulls are to be controlled at the same time. In such a case the surface will preferably be designed as a curved surface, for instance a rotation symmetric parabola, while in other cases the reflector element may be designed just as a plane mirror. An antenna comprising such a reflector element of ferroelectric material can also form a polarization twisting Cassegrain antenna with a flat or curved main reflector element.

Abstract: A method and apparatus for providing a high impedance structure or surface comprising at least one electrically conductive wire forming at least one elongate wire spiral, the at least one elongate wire spiral being defined by a plurality of spirals of said at least one wire, the spirals having a pitch and being spaced apart along a major axis of said elongate wire spiral; and an arrangement for varying the pitch of the spirals of said at least one wire to thereby tune the impedance of said tuneable impedance structure. An embodiment useful as an antenna aperture to steer a radio frequency beam having two different polarizations is disclosed.

Abstract: A method and apparatus for producing contiguous spot beam communications coverage on the Earth's surface are disclosed. The apparatus comprises an antenna system including two wide scan antennas and two narrow scan antennas. The two wide scan antennas are disposed substantially opposite each other, and the two narrow scan antennas are disposed substantially opposite each other and substantially normal to the wide scan antennas. The first wide scan antenna, second wide scan antenna, and first narrow scan antenna produce a first beam pattern on a planetary surface and the first wide scan antenna, second wide scan antenna, and second narrow scan antenna produce a second beam pattern on the planetary surface.

Abstract: A beam steerer for steering a microwave beam comprises a body of magnetic material having an aperture and magnetic coils for applying a gradient of magnetization across the aperture. Tapered slots extending from the magnetic coils towards a central region of the aperture are filled with a material having a lower magnetic permeability than the magnetic material of the body. Lower reluctance paths available through the central region of the aperture allow more magnetic flux from the magnetic coils to penetrate through the central region than would be the case in a body of uniform material composition.

Abstract: An antenna device comprised of dielectric elements, the device having an array of parasitic director elements which coherently focuses energy across the parasitic array. The parasitic elements are spaced less than or equal to one wavelength from each other to provide the coherent focusing, with the array thereby acting like an artificial dielectric lens. An optimal spacing or elemental length might include one-eighth (⅛) to one-quarter (¼) wavelength. A plurality of feed elements is associated with the array and provides incident energy thereon. Reflector elements might also be used to further reflect incident energy from a feed element back across the parasitic array. The various elements are switchably selectable via a switching network which might consist of diodes. The parasitic elements form a lens which provides the directionality of the antenna.

Abstract: The present invention relates to a method for producing a shell for a Luneberg lens in which an amount of a dielectric material composition containing particles of an expandable plastic material coated with an amount of a titanium-oxygen compound, is introduced into a mould and heated to an appropriate temperature for moulding. As a plastic material use is made of an expandable plastic material which is non-expanded or partly pre-expanded. The moulding temperature is selected such that expansion of the particles takes place. As an expandable plastic material preferably use is made of polystyrene. The dielectric moulding composition preferably comprises 5-65 wt. % of the titanium-oxygen compound with respect to the total weight of the composition.

Abstract: In an adaptive antenna device having directivity pattern generators operable in accordance with different algorithms, respectively, in a baseband modem, beam steering processing, null steering processing, and estimating processing of an arrival direction are executed in parallel to one anther. Parameters resulting from the beam and the null steering processing are controlled by processing results of the estimating processing and are weighted and combined to individually generate directivity patterns based on the different algorithms.

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: A Luneberg lens has a plurality of feeds arranged to send and receive signals to and from a plurality of satellites. The lens is spherical and is fixedly supported on a support mount. Also supported on this mount are a plurality of arcuate positioner tracks which form arcs parallel to the surface of the lens. Each of the feeds is mounted on a separate one of these tracks. The tracks are supported on the mount for separate pivotal motion along separate paths equidistant from the surface of the lens about a “y” axis relative to the lens. A motor is coupled to the drive of each of the tracks to pivotally drive its associated track in response to control signals. The feeds are mounted on the tracks for motion in paths about an “x” axis relative to the lens, such paths being equidistant from the surface of such lens. A motor drives each of the feeds in response to control signals along separate paths parallel to the lens surface.

Abstract: An antenna device has less change in gain during beam scanning, caused by the displacement of a primary radiator with respect to a dielectric lens, and scanning can be carried out over a large angular range at uniform gain. A primary radiator has a focal plane in a position deviating from the optical axis of a dielectric lens, and when the primary radiator intersects the optical axis, the primary radiator leaves the focal plane. As a consequence, by moving the primary radiator away from the optical axis to other positions, change in the gain caused by change in the open efficiency and aberration can be reduced.

Abstract: A method and a device is disclosed for the generation of a lens device including a plate of ferroelectric material, the transmission phase gradient of which is be varied over the lens by means of a controllable static electric field. The lens may involve an entire antenna aperture, e.g. a feeder horn or constitute a body covering a slotted wave-guide antenna, be a portion of an antenna aperture or an element in a conventional array aperture. The division of the aperture depends on the number of degrees of freedom to be controlled simultaneously. In a general case N lobes and M nulls are to be controlled at the same time. In the most simple case with N=1 and M=0 the lens should be the entire antenna aperture. The invention is based on the fact that the direction of the wires of the control grids (1, 2) in the lens device must run perpendicular to the direction of the E-field direction of a penetrating high frequency radio wave.

Abstract: A phase shifting array antenna includes antenna elements that have a non-electrically conductive substrate having first and second sides, an electrically conductive patch formed on the first side of the substrate, and a ground plane formed on the second side of the non-electrically conductive substrate. At least two pairs of integrated microelectromechanical switches are arranged diametrically opposed across the patch on the first side of the substrate, each microelectromechanical switch having a first electrode electrically coupled to the patch and a second electrode electrically coupled to the ground plane, the first and second electrodes being operable to be capacitively coupled, thereby creating a short circuit plane across the patch. A sealing structure hermetically packages the microelectromechanical switches.

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.