Abstract: An active array radar system is controlled by photonic signals. The array of N antenna elements is divided into M subarrays, each having N/M antenna elements. Tunable lasers provide M optical wavelengths within non-overlapping bands. For transmission, a microwave transmit pulse is amplitude modulated onto the M optical signals. Time delays are introduced for an offset between elements in a subarray and for an offset between subarrays. By using wavelength division multiplexing each antenna element on the array has a true time delay.

Abstract: An active array radar system is controlled by photonic signals. The array of N antenna elements is divided into M subarrays, each having N/M antenna elements. Tunable lasers provide M optical wavelengths within non-overlapping bands. For reception, the microwave signals are optically modulated onto a single fiber for each subarray. Time delays are introduced for an offset between elements in a subarray and for an offset between subarrays. By using wavelength division multiplexing, a true time delay is attributed to each antenna element on the array. A non-coherent optical combiner having an array of N photodetectors demodulates the receive signals and recovers the coherent sum of the RF signals.

Abstract: A radar system includes a null processor coupled to transmit receive modules. The null processor inserts nulls in the sum pattern at locations for suppressing a jamming source. The null processor determines the difference pattern based upon the product: sum*sin(x), where sum is the sum pattern and x is the azimuth angle.

Abstract: An integrated directional patch antenna uses multiple patch radiating elements to control the direction of a beam of radio frequency energy (RF) over a large scan volume. The antenna includes a ground plane element and a first dielectric planar member placed on a major surface of the ground plane element. A plurality of first patch radiator elements is arranged on a surface of the first dielectric member remote from the ground plane element. A second dielectric planar member is placed on first patch radiator elements, and a plurality of second patch radiator elements arranged on a surface of the second dielectric member remote from the first patch radiator elements.

Abstract: A switching unit for a photonic phased array for use in the microwave frequency bands uses lasers and other photonic devices to perform various functions in the phased array such that signals can be carried to the antenna elements on a single optical fiber. In one embodiment of the invention, a set of fixed phase shifters generates signals each having different phases. In the switching unit, each resulting signal, which is of a particular phase, modulates a laser of a different color. Each different laser color is thus associated with a given phase. Alternatively, time-delay units produce signals of different time-delay states which signals are then associated with lasers of different colors. The lasers are then used for selection of the signals to be applied to each element in the array. The laser signals are combined and carried on a single optical fiber to an optical network of tunable optical filters which can be located at the element level.

Abstract: A communications card having an antenna assembly providing polarization diversity for use with a portable computer is provided. The antenna assembly comprises two folded antennas, which may be dipoles or slot radiators, that are disposed orthogonally to one another to provide polarization diversity. Signals are carried to and from the antenna by microstrip feed lines. The microstrip lines are placed off center along each antenna slot to establish an acceptable impedance match for the antenna. The feed lines are coupled to the communications card by way of coaxial cables. The antenna assembly is coupled with the communications card in a hinged arrangement thus allowing for spatial redirection of the antenna, if desired.

Abstract: A single radiating structure with an integrated mode transducer that produces near-ideal radiation characteristics at two frequency bands. The dual band feed consists of three main sections: feed waveguide, mode transducer and corrugated horn. The feed waveguide consists of two concentric, circular waveguides that are excited in the TE.sub.11 coaxial and circular waveguide modes for the low and high bands, respectively. The mode transducer, which is critical to the performance of the feed, provides a single mode, low return loss transition, for both bands, between the feed waveguide and the corrugated horn. This is achieved by converting the TE.sub.11 circular waveguide modes into the fundamental hybrid, HE.sub.11, mode of the corrugated horn. The corrugated horn, which is a stepped-slot configuration, is designed to achieve a smooth transition from the mode transducer and to produce the desired radiation characteristics at both frequency bands.

Abstract: An active array radar system is controlled by photonic signals. The array of N antenna elements is divided into M subarrays, each having N/M antenna elements. Tunable lasers provide M optical wavelengths within non-overlapping bands. For reception, the microwave signals are optically modulated onto a single fiber for each subarray. Time delays are introduced for an offset between elements in a subarray and for an offset between subarrays. By using wavelength division multiplexing, a true time delay is attributed to each antenna element on the array. A non-coherent optical combiner having an array of N photodetectors demodulates the receive signals and recovers the coherent sum of the RF signals.