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 reflector for an antenna includes a plurality of reflector elements, each having a transmission line and an aperture at a distal end of the transmission line. Each transmission line having a length which varies in accordance with the position of each aperture relative to the antenna. The varying length of transmission creates a time delay that phases re-radiated waves.

Abstract: A scanning antenna with ferrite control comprising a waveguide consisting of top and bottom ferrite layers and an intermediate layer. An array of radiating dipoles situated at the upper surface of the top ferrite layer. A horn structure containing first and second horn elements extending longitudinally along both sides of the array of radiating dipoles. Each horn element has an engaging part, a spacing part, and an inner wall. The spacing parts extending along and spaced from the top ferrite layer forming respective gaps therebetween. Dielectric spacers are provided at both sides of the array of dipoles and placed within the respective gaps. Each horn element is formed with at least one groove extending inwardly from the respective spacing part and longitudinally along the axis of the waveguide. The longitudinal grooves and the dielectric spaces restrict excitement of the parasitic modes in the waveguide and reduce power losses in the antenna.

Abstract: An RF/ID transponder comprises an integrated circuit package including at least a memory and an RF modulator. A dipole antenna is coupled to the RF modulator, and has a length greater than one-half wavelength of an electromagnetic wave having a nominal frequency within an operating frequency band of the RF modulator. A base plate provides an electrically conductive ground plane, and a housing is attached to the base plate. The integrated circuit package and the dipole antenna are supported by the housing at a predetermined distance from the conductive ground plane. Thereby, the dipole antenna provides a radiation pattern that includes at least first and second squinted beams extending at respective acute angles relative to a vector defined normal to the conductive ground plane, and at least one center beam extending along the vector defined normal to the conductive ground plane.

Abstract: A two-dimensionally steered antenna system (40) includes a planar lensing system (64, 94) operable to focus signals received from a plurality of ground-based cells (20). A first steering system (66) is operable to steer a beam (32) for each ground-based cell (20) in a first direction by weighing signals associated with the ground-based cell (20) based on a position of the antenna system (40) relative to the ground-based cell (20) in the first direction. A second steering system (96) is operable to steer the beam (32) for each ground-based cell (20) in a second direction by weighing signals associated with the ground-based cell (20) based on a position of the antenna system (40) relative to the ground-based cell (20) in the second direction.

Abstract: A millimeter wave imaging system includes a plurality of millimeter wave radiometer elements disposed in a sparse antenna array integrated into a lower surface of an airborne vehicle. The antenna elements preferably form a cross or T-shaped sparse array. Images are formed using interferometric techniques. Each radiometer element includes a receive antenna coupled to an electronic mirror which provides beam steering. To compensate for deflection of the airborne vehicle, a mechanical deflection measurement system is provided. Additional radiometer elements having transmitter antenna elements may be integrated into the sparse array to provide active illumination to enhance image formation and to operate as target designators.

Abstract: An antenna device and a transmitting and receiving unit using the device which are capable of simultaneously polarizing each direction of a plurality of beams are provided without increasing the size of the whole device. For example, when the detection is achieved by forming a plurality of beams such as a radar of monopulse type, the angle measurement range is easily extended. A movable part is provided with a plurality of primary radiators and movable part side transmission lines (dielectric strips of NRD guide) to be coupled therewith, and a fixed part side is provided with dielectric lenses to form each focal plane at the position of primary radiators, and fixed part side transmission lines (dielectric strips of NRD guide) to be respectively coupled with the movable part side transmission lines. A plurality of beams are simultaneously tilted by displacing the movable part.

Abstract: An antenna subsystem (120) which comprises an electronic scanning reflector antenna (400) is used for the formation of single and multiple beams. Reflecting surface (420) is covered with at least one dielectric layer (430) which is used to simultaneously and independently steer multiple beams. Electronic scanning reflector antenna (400) operates similar to a phased array antenna. ESRA (400) comprises a number of independent controllable reflecting surfaces (450) which are combined together in close proximity. Each one of the individual regions is covered by a dielectric layer, and the dielectric constant for each can be independently controlled. Electronic scanning reflector antennas (400, 600) are used in both space-based and terrestrial-based applications. Electronic scanning reflector antennas (400, 600) are used for both transmission and reception of electromagnetic signals.

Abstract: An antenna element is disclosed with a microstrip transmission line having a series of conductive patch radiating elements, each one of the radiating elements having a pair of conductive patches, each one of the patches being disposed on opposite edges of the transmission line, each of the patches having a rhomboidal shape with edges disposed at an oblique angle with respect to the microstrip transmission line, the edges of one of the patches being at substantially ninety degrees to the edges of the other one of the patches, the patches being staggered with respect to each other along the transmission line by substantially a quarter-wave length at the nominal operating wavelength of the antenna element.

Abstract: A novel means of scanning a circularly polarized reflectarray antenna. The reflectarray is an array of metallic elements arranged on a surface designed to compensate for the various path lengths of the optical rays from an illuminating feed to the reflecting surface and then to the antenna aperture. With appropriate design, the phase in the aperture can be made to vary linearly in any desired direction and also to produce a radiated beam normal to the constant phase surface. In the case of circular polarization, this path length compensation can be accomplished by rotation of the individual elements.

Abstract: A reflectarray antenna for achieving increased dynamic phase range has a plurality of dipole elements positioned across the antenna surface. The elements include a single dipole element having a predetermined length that is approximately proportional to the dynamic phase range through which the first dipole element can reflect. The elements also include a coupled dipole element which comprises a longer dipole and a shorter dipole. The longer dipole and the shorter dipole are positioned on the reflectarray surface such that they are spaced a predetermined distance apart.

Abstract: Varying the azimuth and elevation beam patterns for an antenna. For a horn-type antenna implemented by a parallel-plate waveguide structure, an input port can accept an electromagnetic signal and an output slot can transmit the electromagnetic signal. An azimuth lens can be placed proximate to the output slot for adjusting the antenna beam pattern within the azimuth plane. The azimuth lens comprises two or more lens elements, each typically having a cylindrical shape and comprising a dielectric material, which support the generation of discrete beams in the azimuth plane in response to the electromagnetic signal output by the output slot. These discrete beams can sum in-phase to form a composite beam having a shape or pattern generally defined by the characteristics of the azimuth lens elements. Specifically, this composite beam has a pattern within the azimuth plane defined by the size and shape of the azimuth lens elements and the spacing between these elements.

Abstract: A user terminal (110) which comprises an electrically-controllable back-fed antenna (300, FIG. 3) is used for the formation of single and multiple beams. The electrically-controllable back-fed antenna comprises an RF power distribution/combination network (310), electrically-controllable phase-shifting elements (320), a control network (440, FIG. 4) and radiating/receiving elements (360). The control network is coupled to the electrically-controllable phase-shifting elements and is used for controlling the dielectric constant of dielectric material contained within the electrically-controllable phase-shifting elements. In a preferred embodiment, phase-shifting elements comprise waveguide sections containing at least one dielectric material, and the dielectric material includes a ferroelectric material, preferably comprising Barium Strontium Titanate (BST).

Abstract: An antenna system having a front reflector and a rear reflector arranged in tandem, a front feed for illuminating the front reflector, and a rear feed for illuminating the rear reflector. Each of the reflectors has a generally dish-shaped configuration, and the feeds are located in positions offset from axes of the respective reflectors. The front reflector is reflective to a first radiation, while being substantially transparent to a second radiation except for a fraction of the power of the second radiation. The fractional part of the second radiation is reflected from the first reflector as an interfering beam, the interfering beam being scanned away from a coverage region of a beam of the first radiation by an offset between the feeds. The radiations may differ in polarization or in frequency.

Abstract: A phased array antenna is designed for scanning a narrow beam over an angular sector that is wide in one plane, and narrow in another, while using a minimum number of phase steering controls. High directivity elements occupy a rectangularly shaped area which is large in one direction relative to a second direction, the elements being staggered in position with neighboring elements to suppress near-in grating lobes. The elements are independent and identical to one another so that conventional array beamforming techniques may be utilized.

Abstract: A low cost microwave antenna. Microwaves are radiated from or collected by a thin layer radiating-collecting microwave guide section in which a dielectric slab is sandwiched between a metallic bottom plate and a metallic radiating-collecting cover plate. The cover plate contains a large number of slots spaced to produce outgoing or define incoming microwaves beams having directions determined: (1) by the directions of propagation of microwave radiation within the radiating-collecting microwave section and (2) by the frequency of the radiation. In a collection mode, a microwave lens focuses microwave radiation propagating in the waveguide section at focal locations which are dependent on the direction of propagation of the radiation in the waveguide. Alternatively, in a radiation mode, the lens converts microwave energy broadcast from said focal locations into parallel beams propagating in the radiating-collecting microwave guide section.

Abstract: A low cost, compact, electronically scanned millimeter wave (MMW) lens enables the projection of a highly directional beam of Ka band millimeter wave (MMW) electromagnetic energy, while eliminating the need for mechanical movement of the lens. The present invention allows for the economical production and operation of the lens in the Ka and higher frequency ranges by exploiting waveguide technology. The waveguides of the present invention are tapered longitudinally resulting in a wider portion of the waveguide in electromagnetic communication with an interior cavity of the lens. The waveguide taper improves impedance matching between the waveguides and the lens cavity. The waveguides also include symmetric power dividers, located longitudinally within the waveguide aperture, ensuring port widths below .lambda..sub.g /2, thus, reducing or eliminating unwanted mode components which reduces sidelobe energy. This results in a low loss, low sidelobe steerable beam of MMW energy.

Abstract: The low profile antenna assembly comprises a generally rectangular frame member housing a planar antenna. A radar absorbing material is attached to the front side of the housing with a radome covering the front side of the planar antenna and attached to the frame member. The planar antenna is a microstrip array fed by a beam forming network that uses either delay lines or phase shifters to electronically steer the antenna pattern horizontally and vertically. The antenna assembly is weatherproofed, painted and flush mounted against a building surface for camouflaging the antenna assembly from observers at a distance.

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: Taking the spiral circumference, C, of a single wire spiral antenna as 2.3 .lambda. (.lambda. being the wavelength at the operating frequency), for example, the beam radiated from an axis Z perpendicular to the antenna surface is tilted. The beam tilt angle changes with the spiral circumference, C, and the spiral circumference, C, is set to between 2 .lambda. and 3 .lambda..

Abstract: An antenna assembly for an active electronically scanned array includes, among other things: an array of antenna elements; an RF signal feed and circulator assembly coupled to said antenna elements and forming thereby an array of radiating structures; a generally planar RF manifold assembly having regularly spaced openings therein located behind and normal to the radiating structures; an array of T/R modules connected to the array of radiating structures and having respective RF connector assemblies forming a portion of an RF interface at one end portion of each of the modules which project upwardly through said spaced openings in the RF manifold and wherein the respective connector assemblies thereof connect to at least one immediately adjacent circulator as well as to transmit and receive manifold portions of the RF manifold; each of the T/R modules further have a heat sink plate on the back side thereof which is positioned against one of a number of elongated liquid coolant circulating coldplates connected

Abstract: A computer vision system is disclosed that utilizes a spinning array of podetectors. The array is rotated about the focal plane of a lens and scans all the possible orientations and positions of the edges of the unknown object. In one embodiment, the photodetectors are elongated so as to provide for maximum light gathering ability along the direction of elongation and a minimum light gathering ability in the direction perpendicular to the direction of elongation. In other embodiments, optical means are used to focus the image onto conventional photodetectors while still having the ability to more efficiently determine edge segments of unknown objects. The system efficiently and rapidly implements the wavelet projection transform to characterize-multi-scale edge segment features of an image of an unknown object. An imaging radar system that utilizes a spinning antenna system having frequency scanning provisions is also disclosed.

Abstract: The single channel transceiver with polarization diversity is a target detion and tracking system that results from combining the well-established technology of single channel transceiver with that of microstrip polarization-diverse antenna. The single channel transceiver with polarization diversity transmits a pair of pulses of a pre-selected polarization sense toward a target object and receives two scattered pulses of orthogonal polarizations in rapid sequence. Thereupon, a second pair of pulses, this time of opposite polarization, is transmitted and, again, two scattered pulses of orthogonal polarizations from this second pair of transmitted pulses are received in rapid sequence. Thus, the single channel transceiver with polarization diversity has the capability to obtain the complete scattering matrix of a target by use of four transmitted pulses.

Abstract: A frequency selective surface filter (20 or 50) particularly useful in connection with a transmit antenna (10) for passing and rejecting signals in multiple frequency bands. According to one embodiment, the frequency selective surface filter (20) has a single conductive screen (24) disposed on a dielectric medium (22). The single-conductive screen (24) includes an array of parallel intersecting lines (26) and (28) providing low frequency filtering. The single-conductive screen (24) also includes an array of double-loop conductive elements each made up of an inner conductive loop (32) and an outer conductive loop (30). According to a second embodiment, the frequency selective surface filter (50) contains two dielectrically separated conductive layers including a first conductive layer (52) having an array of double-slots made up of an inner slot (64) and an outer slot (66). The double-slot configuration further includes a second conductive layer (60) made up of an array of single conductive loops (62).

Abstract: A scanning array antenna (300) produces a directional beam by differentially rotating two, co-axial, flat phasing plate assemblies (302, 304). Each plate (302, 304) consists of a phase shifting means designed to efficiently pass incident radio frequency (RF) energy while imparting a particular phase shift to the energy. The energy can be supplied by a feedhorn (406) located behind the plates (402, 404) or can be introduced above the plates (508) and reflected by a ground plane (506) on the bottom plate (504). A method for producing the directional beam using the scanning array antenna (300) determines (804) the desired beam direction, calculates (806) the appropriate plate rotation angles (326, 328), and rotates (808) the plates (302, 304) at the appropriate time.

Abstract: A UHF phase shifter including a UHF waveguide having an electrooptical element lying between two elements 3 and 4 made of materials which have permittivity higher than that of the electrooptical element. An electric polarization field is applied for controlling the electrooptical element and a UHF line is inserted into the element. The control of the orientation of the molecules of the electrooptical element allows for a variation of the index of the element as seen by the field of a UHF wave.

Abstract: A reconfigurable multiple beam phased array antenna has radiating elements arranged in a planar array and variable phase shifters. Each one of the phase shifters is connected to a respective one of the radiating elements. The array antenna further includes a beam forming network for forming spot and regional beam signals. The beam forming network forms a regional beam signal from a combination of spot beam signals. The beam forming network has two dimensional stacks of Rotman lenses provided with a first set of ports. Each one of the first set of ports is connected to a respective one of the radiating elements with. The Rotman lenses generate frequency invariant spot beam signals which are communicated between the radiating elements and the Rotman lenses via the first set of ports for transmission and reception of spot beams and regional beams by the radiating elements. The phase shifters are adjusted to steer the spot and regional beams to desired locations.

Abstract: A low profile receiving and/or transmitting antenna includes an array of lenses that focuses millimeter wave or other radiation onto a plurality of conventional patch antenna elements. The lenses and antenna elements are physically configured so that radiation at a tuning wavelength impinging on the antenna at a particular angle of incidence is collected by the lenses and focused onto the antenna elements in-phase. Two rotatable prisms may be disposed above the lenses to alter the angle of incidence of incoming or outgoing radiation to match the particular angle of incidence.

Abstract: Terrestrial antennas (10A, 10B, 10C and 10D) which are capable of transmitting and receiving radio signals directly to and from satellites in low Earth orbit are disclosed. The preferred embodiment of the invention employs circularly polarized, dual-frequency printed circuit antenna elements (136) measuring only a fraction of an inch in diameter. One embodiment (10A) includes an elevation array and an azimuth array which both reside on a trapezoidal, semi-conical housing that resembles a flattened pyramid. Both the top and the curved exterior of the pyramid support circular, slotted, printed circuit patches on their surfaces which bound individual radiating antenna elements (18). Since the entire antenna is only a few inches in diameter and is less than two inches high, it can be incorporated as an integral element of a telephone (T) or can be mounted at the end of a collapsible mast (CM).

Abstract: An electronic scan antenna for generating an electrically scanned RF beam in response to an incident RF beam having at least one operating frequency band associated therewith includes a ground plane for reflecting the incident RF beam and a phasing arrangement of plasma structures operatively coupled to the ground plane. Each plasma structure includes gas containing areas which are reflective at the operating frequency range, when ionized, forming ionized plasma areas. Each ionized plasma area is disposed a first distance from the ground plane, a second distance from adjacent ionized plasma areas and each plasma ionized plasma area has a particular size associated therewith. In this manner, each ionized plasma area, in cooperation with the ground plane, provides a portion of a composite RF beam which has a phase shift associated therewith.

Abstract: An omnidirectional isotropic antenna employing a tubular waveguide 12, a dielectric insert 18 which includes a lens 20 and a depending stem 22. The lens 20 is an elliptoid generated by rotating an elliptoid form about the longitudinal axis 42 of the tubular waveguide 12 with its foci 40 aligned with the longitudinal axis 42 and its major axis 38 lying in a zone of rotation 43 intersecting the horizontal plane 44 that is normal to the axis 42 and containing the foci 40. The stem 22 has integrally formed a polarizing element 36, and an impedance to matching element 21. There is provided a passband filter 50 and a modified tubular waveguide 60 that provides node differences for the RF signals.

Abstract: An antenna structure includes a plurality of vertical directed antennas mounted on an insulated cylindrical substrate. A parabolic reflecting antenna is mounted at one end of the cylindrical substrate cavity and a dielectric lens admits radiation through the cylindrical cavity to the parabolic reflector. Optical detectors are located on the cylindrical substrate periphery and exposed to optical signals through an InfraRed (IR) optical filter.

Abstract: An interleaved planar array antenna system providing angularly adjustable linearly polarized beams comprises an array of parallel rows of transmit dipole element pairs and an array of parallel rows of receive dipole element pairs, the two arrays being interleaved. Each of the dipole element pairs includes a first dipole element and a second dipole element adjacent and orthogonal to the first dipole element. All of the first dipole elements are parallel to each other and all of the second dipole elements are parallel to each other. All of the dipole elements are on the same surface and on another surface parallel to and spaced from the first surface there is an array of transmit feed line pairs and an array of receive feed line pairs, with the arrays being interleaved with each other. The transmit feed line pairs are proximity coupled to the transmit dipole element pairs and the receive feed line pairs are proximity coupled to the receive dipole element pairs.

Abstract: The invention relates to an antenna system which is capable of producing multiple, high-gain, independently steerable antenna beams from a single antenna aperture. The system accomplishes this, in part, by utilizing a separate phased array antenna as the feed element of a spherical lens for each desired beam. In this fashion, the beam(s) produced by the antenna system can each be electronically steered (independently of the other beams, if any) and physical movement of the feed element(s) is not required. The invention may also use multiple spherical lenses, wherein each lens includes at least one phased array feed.

Abstract: A waveguide lens antenna system is shown which includes a collapsible support structure and a collapsible waveguide lens array. The collapsible waveguide lens array includes a plurality of integrally connected tubular waveguide cells that form an array which focuses transmitted signals onto a satellite signal processing device. The array is coupled to a support structure that is affixed to a mounting surface, such as a satellite, and that correctly positions the array when the array is operationally deployed.

Abstract: An array of hemispherical dielectric lenses antenna on a ground plane for focusing radiation from an array of point sources, each point source being located adjacent to its respective hemispherical lens. Dual polarization point sources provide dual orthogonally polarized radiation patterns, including right and left hand circularly polarized radiation patterns. The entire antenna and ground plane may be rotated and the array of point sources may be moved relative to the hemispherical lenses so as to scan the antenna beam over a hemisphere.

Abstract: A device for scanning in a scanning axis includes a periodic array of conductive plates disposed along the scanning axis. The device has a periodic array of ferroelectric material slabs disposed along the scanning axis, each slab being disposed between a pair of adjacent conductive plates, adjacent slabs being separated by one of conductive plates. Each of the slabs has a receiving face and a radiating face substantially parallel to each other. Input transmission means feed an input electromagnetic signal to the periodic array of slabs in a propagation direction so that the input electromagnetic signal is incident on the receiving faces of the slabs and so that the electrical component of the input electromagnetic signal received at each receiving face has a component parallel to the scanning axis.

Abstract: An antenna having: a beam forming network; an array of antenna elements; and a parallel plate region coupling the array of antenna elements and the beam forming network formed on a common, folded dielectric substrate. The beam forming network includes strip conductor circuitry separated from a ground plane conductor by a portion of the substrate. The array of antenna elements comprising strip conductor circuitry separate from a ground plane conductor by a second portion of the substrate. The parallel plate region is disposed about a folded region of the substrate and includes a pair of conductive plates separated by the folded region of the substrate. With such arrangement, a compact antenna is provided using the folded substrate. Also, spurious radiation (which has been found to radiate when strip conductor circuitry is disposed about the folded region to couple the array of antenna elements and the beam forming network) is confined by the parallel plate region.

Abstract: A compact scanned antenna which includes a radiator, a rotatable tube and a line source. The radiator is formed by plating a shaped dielectric core. It generates an antenna beam at an output aperture in response to a microwave signal at an input port. The line source generates a radiation sheet which is directed across a signal plane to the input pot. The tube has a cylindrical wall which is positioned across the signal plane. As the tube rotates, refractive or diffractive transmission structures pass through the signal plane. The refractive structures include linear segments which refract the wavefront of the radiation sheet. Because the wavefront slope at the radiator's aperture is a function of the wavefront slope at its input port, the antenna beam is scanned. The linear contour segments have the same inclination but are not colinear. This arrangement reduces the thickness of the tube wall. Phase coherence is achieved by an appropriate radial spacing of adjacent ends of contour segments.

Abstract: Terrestrial antennas (10A, 10B, 10C and 10D) which are capable of transmitting and receiving radio signals directly to and from satellites in low Earth orbit are disclosed. The preferred embodiment of the invention employs circularly polarized, dual-frequency printed circuit antenna elements (136) measuring only a fraction of an inch in diameter. One embodiment (10A) includes an elevation array and an azimuth array which both reside on a trapezoidal, semi-conical housing that resembles a flattened pyramid. Both the top and the curved exterior of the pyramid support circular, slotted, printed circuit patches on their surfaces which bound individual radiating antenna elements (18). Since the entire antenna is only a few inches in diameter and is less than two inches high, it can be incorporated as an integral element of a telephone (T) or can be mounted at the end of a collapsible mast (CM).

Abstract: A scanning folded lens antenna system for scanning reception and/or transmission of electromagnetic radiation and method of scanning receiving and/or transmitting electromagnetic energy. The folded lens has a first cylindrical parallel plate waveguide, a second cylindrical parallel plate waveguide, a waveguide coupler operatively associated with the first and second waveguides to communicate a signal therebetween so as to transform a cylindrical signal from the first waveguide to a substantially planar phase signal in the second waveguide, and a plurality of coupling device operatively associated with first waveguide for coupling a signal between the first waveguide and the coupling device.

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: The invention pertains to an electronic sweep device with integrated active lens and light source.The device includes a bundling of superimposed channels C which are separated by thin metal planes P that include, in front of a metal short-circuit plane (10), illumination organs (S) and phase displacement organs (B).The invention makes it possible to create a compact electronic sweep device which eliminates the parasitic reflection phenomena between illuminator and lens for the purpose of controlling a hyperfrequency beam.

Abstract: An antenna system includes a set of symmetrically located center-fed and segmented dipole antennas embedded on top of a frequency selective photonic bandgap crystal. A two-dimensional array of microelectromechanical (MEM) transmission line switches is incorporated into the dipole antennas to connect the segments thereof. An MEM switch is located at the intersection between any two adjacent segments of the antenna arm. The segments can be connected (disconnected) by operating the switch in the closed (open) position. Appropriate manipulation or programming of the MEM switches will change the radiation pattern, scanning properties and resonance frequency of the antenna array. In addition, an MEM switch is inserted into the crystal to occupy a lattice site in the 3-dimensional crystal lattice.

Abstract: An array of coupled microwave oscillators operate at equally spaced output frequencies to produce a train of high-power RF pulses. Each oscillator is embedded in a printed planar radiating structure so that they form a classical antenna array. The oscillators are coupled through weak radiative interactions and by adjusting the frequencies of the oscillators so that adjacent devices operate at equally spaced frequencies, the output from the array is a frequency spectrum of equally spaced pulses. The pulses have a pulse repetition rate which is determined by the frequency spacing and the pulse duration and peak power are a function of the square of the number of oscillators in the array. In addition, the signal scans repetitively through space above the array.

Abstract: A multiple layer dipole array that provides for a multi-frequency band phased array antenna. Several layers of dipole pair arrays, each tuned to a different frequency band, are stacked relative to each other along the transmission/reception direction. The highest frequency array is in front of the next lowest frequency array and so forth. Due to the frequency selective property of the arrays, incident high frequency signals are completely absorbed by the highest frequency array. In regard to incident low frequency signals, the insertion loss due to higher frequency arrays is small resulting in good performance of the lower frequency arrays. The multi-frequency band phased array antenna may use active or driven dipole pairs, or parasitic elements that form the multiple layer dipoles. The multiple layer dipole array of the present invention may employ corporate feed circuit boards and a corporate feed power divider, using strip transmission line circuits, for example.

Abstract: Microwave apparatus for altering the phase-front of microwave energy propagating in a predetermined path and in which there is provided a panel having a plurality of electrically-conductive leads extending substantially parallel to the electric vector of the wave, each of these leads is lengthwise divided into sections. A semiconductor junction is formed in the semiconductor material at each end of each section of lead. Each pair of confronting junctions together with the semiconductor material therebetween provide a surface oriented semiconductor diode switch. A switching voltage is applied to each of the leads so as to render at least some of the diodes in each of the leads simultaneously either conductive or non-conductive, thereby allowing each of the leads to be electrically either divided into said sections or continuous throughout at least a portion of its length.

Abstract: A satellite-based cellular telecommunications system employing a constellation of telecommunications satellites in medium earth orbit to provide multibeam radio frequency (rf) communications links for worldwide cellular telephone service with a minimum number of satellites. The telecommunications satellites are placed in a plurality of inclined orbits about the earth at an altitude of between approximately 5600 and 10,000 nautical miles. The characteristics of the orbits, such as the number of orbits, the inclination of each orbit, the number of satellites in each orbit and the altitude of the satellites, are tailored to maximize the coverage area of the satellites and their related line-of-sight elevation angles, while minimizing propagation time delays, the number of beam-to-beam and satellite-to-satellites handovers, and the total number of satellites.

Abstract: The usable range of incidence angles for electromagnetic wave polarizers using arrays of polarizer elements is increased by introduction of a dielectric medium having a dielectric constant large enough to reduce the angle of wave incidence upon the polarizer elements. For example, arrays of 45 degree inclined meander-line polarizer elements are encased in a dielectric medium having a dielectric constant of about 3. The polarizer includes impedance matching layers at the surfaces of the dielectric medium to reduce reflections at those surfaces. The resulting polarizer is indicated to be usable to reciprocally convert an incident polarization to a desired polarization (e.g., from linear to circular polarization) for waves with incidence angles from zero to 70 degrees in any plane.

Abstract: A satellite-based cellular telecommunications system employing a constellation of telecommunications satellites in medium earth orbit to provide multibeam radio frequency (rf) communications links for worldwide cellular telephone service with a minimum number of satellites. The telecommunications satellites are placed in a plurality of inclined orbits about the earth at an altitude of between approximately 5600 and 10,000 nautical miles. The characteristics of the orbits, such as the number of orbits, the inclination of each orbit, the number of satellites in each orbit and the altitude of the satellites, are tailored to maximize the coverage area of the satellites and their related line-of-sight elevation angles, while minimizing propagation time delays, the number of beam-to-beam and satellite-to-satellites handovers, and the total number of satellites.