Abstract: The present invention provides an antenna system including a body for use in determining N unknown parameters values relating to an object located in the vicinity of the system. The system further includes an antenna array comprised of a plurality of elements that are spaced to reduce ambiguities in the subsequently determined N values. In one embodiment, several pair of elements are used. The spacing between the elements comprise the pairs and the spacing between pairs reduces ambiguities. The antenna system also includes a beamformer for producing a plurality of beams and a device for using the plurality of beams to determine N values associated with the object. The amplitude of the plurality of beams can be compared to obtain coarse data on the object.

Abstract: The present invention provides an improved antenna system that, in one embodiment, includes an antenna array comprised of a plurality of elements, each of which is capable of providing a signal. Also included in the improved antenna system is a multi-beam beamformer for producing two spatially independent overlapping beams from the signals provided by two different subsets of the antenna array. The phase of the two beams is compared to realize an interferometer that can provide high or fine resolution data on the position of an object relative to the antenna system. The amplitude of the two beams can also be compared to obtain coarse data on the position of the object. The beamformer includes a switching network for selecting which elements of the antenna array form the two subsets. This permits, for example, the position of the beams to moved, the baseline of the two beams to be varied, and/or the beam width of the beams to be altered.

Abstract: An antenna apparatus capable of generating scanning beams through a range of 0°-90° is provided. The antenna apparatus includes one or more rows of antenna elements, with the antenna elements in each row being arranged in pairs. The elements within a pair are separated by a distance of about lambda/four, and the pairs are separated by a distance of about lambda/two, where lambda is the wavelength of the center frequency of signals transmitted from the antenna apparatus. Transmit/receive circuitry may be electrically connected to each pair of antenna elements, with the signal to elements within a pair having a phase quadrature relationship so that the pair of antenna elements generates a scanning beam in one direction and a control pattern null is achieved in another direction. A control system controls the generation of a scanning beam output by the antenna apparatus.

Abstract: A cross-link antenna system including a plurality of spacecraft in a constellation is provided. Each of the spacecraft includes an antenna. One or more of the antennas has a number of antenna elements that can be controllably energized. Determined or selected phases and amplitudes can be individually applied through phase shifters and amplifiers to the antenna elements. In determining phase values for energizing the antenna elements to provide the receive beam in the direction of the current transmit antenna of one of the spacecraft in the constellation, location information is obtained for the transmit spacecraft and each of the beam receiving spacecraft. Additionally, attitude information for each receive spacecraft is found and location information associated with each of the antenna elements for each receive antenna is obtained.

Abstract: A radio frequency reconfigurable lens is provided. In particular, a lens comprising at least two opposed frequency selective surface sheets is provided. A relative phase shift may be imparted to an incident radio frequency wave by varying the distance between at least some of the unit cells of a first of the FSS sheets and adjacent unit cells on a second of the FSS sheets. In order to provide a desired phase taper across the width of a lens, and/or to provide different phase shift amounts, pairs of FSS surfaces having controllable columns or rows can be cascaded together. According to an additional aspect of the present invention, radio frequency waves can be scanned by cascading multiple tunable stages. The present invention also provides a radio frequency shutter.

Abstract: A cross-link antenna system including a plurality of spacecraft in a constellation is provided. Each of the spacecraft includes an antenna. One or more of the antennas has a number of antenna elements that can be controllably energized. Determined or selected phases and amplitudes can be individually applied through phase shifters and amplifiers to the antenna elements. In determining phase values for energizing the antenna elements to provide the receive beam in the direction of the current transmit antenna of one of the spacecraft in the constellation, location information is obtained for the transmit spacecraft and each of the beam receiving spacecraft. Additionally, attitude information for each receive spacecraft is found and location information associated with each of the antenna elements for each receive antenna is obtained.

Abstract: A dual band coplanar microstrip interlaced array antenna is provided. The antenna may be confined to a relatively small area, while providing dual band operation with no or minimal grating lobes and losses. According to the present invention, first and second arrays are interlaced with one another to minimize the surface area of the antenna. A maximum spacing between array elements is selected based on the operating wavelengths and scan range for each of the arrays. A first dielectric constant of a material underlying elements of the first array is calculated from the selected element spacing and the operating wavelength of the first array. A second dielectric constant of a material underlying elements of the second array is calculated from the first dielectric constant and the operating frequencies of the first and second arrays. The present invention provides a dual band coplanar microstrip interlaced array antenna capable of efficient operation at two center frequencies.

Abstract: An antenna apparatus that includes a beam control system and a beam collimating system having a compound curve antenna structure is provided. The compound curve antenna structure can be two-dimensional or three-dimensional. In one embodiment, the curve is parabolic and the compound curve antenna structure includes first and second parabolic reflector sections that are spaced from each other. A feed array of the beam control system is disposed therebetween at the base ends of the two parabolic reflector sections. When the compound curve antenna structure is three-dimensional, the two parabolic reflector sections are part of a body of revolution. The control system also includes memory storage that stores predetermined data related to controlling activation of each of a plurality of feed elements of the feed array. The predetermined data is based on information obtained using a reference beam with the compound curve antenna structure.

Abstract: An antenna apparatus that includes a beam control system and a beam collimating system having a compound curve antenna structure is provided. The compound curve antenna structure can be two-dimensional or three-dimensional. In one embodiment, the curve is parabolic and the compound curve antenna structure includes first and second parabolic reflector sections that are spaced from each other. A feed array of the beam control system is disposed therebetween at the base ends of the two parabolic reflector sections. When the compound curve antenna structure is three-dimensional, the two parabolic reflector sections are part of a body of revolution. The control system also includes memory storage that stores predetermined data related to controlling activation of each of a plurality of feed elements of the feed array. The predetermined data is based on information obtained using a reference beam with the compound curve antenna structure.

Abstract: A deployable reflector for an electronically scanned reflector antenna is provided. The deployable reflector may be confined to a relatively small volume for transportation of the reflector to a deployment site. Upon deployment, the reflector of the present invention forms a relatively large reflector surface, having a precisely controlled surface geometry. The reflector generally includes a plurality of panel members interconnected to a plurality of ribs interconnected to an extendable boom. The antenna reflector of the present invention is particularly well suited for a space-based antenna, where a reflector that can be collapsed into a small volume for transport and deployed to form a large reflector surface having high gain is desirable.

Abstract: A multi-frequency radome includes a material-tuned radome portion for generating a low frequency passband of the radome and an integrated low pass frequency selective surface (FSS) portion for tuning a high frequency passband of the radome. The FSS portion provides a reactance necessary to move an upper passband of the material-tuned radome to a desired spectral location. Because the FSS portion is a low pass structure relative to the low frequency passband of the material-tuned radome portion, it does not substantially affect the low frequency passband when the FSS portion is applied to the material-tuned radome. In one embodiment, the FSS portion is designed to take advantage of various well known properties of FSS structures, such as the ability to tune for angle of arrival and polarization properties.

Abstract: A method an apparatus for calibrating an electronically scanned reflector (ESR) antenna to compensate for mechanical distortions in a reflector and feed thereof first determines displacement values for a multitude of points on the reflector and the feed. The displacement values are then analyzed to determine the types of distortion, if any, that are present within the ESR antenna system. Compensation values are then determined for each of a plurality of beam positions based on the type(s) of distortion identified. The compensation values are stored in a lookup table for later use in generating antenna beams in the corresponding beam position.

Abstract: An antenna apparatus for generating transmit signals, receiving return signals based on the transmit signals, and/or receive transmitted signals from other sources is provided. The antenna apparatus includes a beam forming system and a beam collimating system. The beam forming system includes an array of feed elements. Each feed element can be used to generate more than one primary beam, either substantially at the same time or at different times. A secondary beam is developed from the primary beam using the collimating system. The secondary beam constitutes the transmit signal. The feed elements have relatively low gain, the spacing between them is no greater than about one wavelength, and they are relatively small in size to reduce beam-to-beam cross over loss. The beam forming system also includes a control system for energizing different feed elements using the same transmit/receive modules.

Abstract: An antenna element is provided that includes a frequency selective surface (FSS) portion on its primary radiating/receiving surface. The antenna element is conductively or capacitively coupled to an RF feed structure that can also include an FSS portion. In a preferred embodiment, the FSS antenna portion is located at least partially within the radiation pattern of a second antenna that operates in a frequency range for which the FSS is substantially transparent. In this way, signals being transferred to or from the second antenna through space can travel through the FSS antenna portion with little attenuation and/or reflection.

Abstract: The present invention relates to an antenna system which is capable of multiband operation from a single antenna aperture. The system provides a high degree of design freedom for achieving desired antenna pattern shapes for all relevant frequency bands. The system achieves this pattern shaping ability by utilizing a unique array configuration which is highly adaptable. The array configuration may include a center array element for each of the relevant frequency bands. In one embodiment of the present invention, a dual frequency band antenna is provided which includes a stacked patch element as the center element in a first frequency band and a crossed dipole element, mounted on top of the stacked patch, as the center element in the second frequency band.

Abstract: An antenna structure is provided having one or more spiral antenna arms extending outwardly from a lateral center axis. Each arm is defined by an antenna element disposed in a zig-zag configuration to provide reactive loading to the arm, wherein each arm receives or transmits radio frequency waves about a longitudinal center axis of the arm and the zig-zag element configuration. Thus, the antenna structure has a broader bandwidth than other antennas requiring the same amount of space. The antenna structure also has a substantially omni-directional radiation pattern and a low profile. Each antenna element can be metallisation disposed on a support structure or can be one or more cable conductors. A feed means is provided which can be connected to the elements proximate to the lateral center axis and positioned along or coincident with the longitudinal center axis of one arm or can be connected to one of the elements distal to the lateral center axis.

Abstract: A microstrip antenna structure comprising a radiator layer that includes a substrate layer and a radiator patch that is disposed on one surface of the substrate layer; a ground plane; and support elements, formed as an integral part of either the radiator layer or the ground plane, for maintaining a dielectric space between the radiator patch and the ground plane that includes an air gap of predetermined thickness between the substrate layer and the ground plane. The present invention also includes a method for constructing such a microstrip antenna structure.

Abstract: The present invention provides a portable communication system with functional components whose functions are not readily apparent to an observer. One embodiment of the system includes a carrying case in which the antenna portion of the communication system is concealed between the shell of the case and an inner liner; a reflector to protect the radio portion of the system from electromagnetic radiation and direct electromagnetic radiation to or from the antenna that is covered so that it simulates the appearance of the file folder portion of a briefcase; and a radio that is covered with a shell upon which are mounted the keyboard and CRT of an actual personal computer or a simulation thereof, so that when the case is open, it appears to contain a laptop computer.

Abstract: The present invention provides a microstrip antenna that includes a microstrip element with an integral member which is used to establish an electrical connection between the microstrip element and a transmission line. The use of the integral member to establish this electrical connection yields advantages in performance, reliability, and manufacturing, among others, that make the microstrip antenna particularly suitable for mobile applications. The present invention also provides a method of manufacturing such a microstrip antenna.

Abstract: A broadband dual polarized antenna includes pairs of electrically separated stacked spiral antenna arms. Each pair of spiral arms have opposite senses and are orthogonal to each other. The relative overlap of each pair of spirals is kept to a minimum so that radiation received and transmitted by the bottom pair of spiral arms will be degraded as little as possible. No overlap exists within each pair of spiral arms, and the pair need not be co-planar, but do share a common axis with the other pair of spiral arms. The spiral arms can be segmented or may comprise a number of spiralling wire elements. A plurality of such antenna structures can be formed into an array capable of beam shaping or scanning.