Abstract: An antenna assembly includes a conducting ground plane, a single dielectric substrate layer or a plurality of dielectric substrate layers each with different dielectric constants mounted to the conducting ground plane. A central patch element is mounted to the dielectric substrate layer or layers and configured to radiate within a first frequency band. A plurality of probes (i) extend through the conducting ground plane and the dielectric substrate and (ii) are physically connected to the central patch element. A parasitic ring is disposed around the central patch element and reactively coupled thereto. The parasitic ring is configured to radiate within a second frequency band.

Abstract: A microwave phase shifter for use in waveguide transmission line employs a piezoelectric cantilevered bimorph member mounted on the waveguide and a thin wafer of dielectric material mounted on the free end of the cantilever above a slot in the waveguide. Voltages applied to the bimorph member cause this member to distort so as to insert the wafer into the waveguide slot and alter the phase of the microwave signal being transmitted.

Abstract: An improved dome antenna system wherein compensation for cross polarized signal components in a received difference pattern of the feed array of the system is accomplished with a second array cross polarized to the feed array. This second array is density tapered to establish an aperture distribution function that is substantially equal to the aperture distribution function of the feed array. Weighting factors, programmed as a function of the boresight scan angle, are applied to the output signals of this second array and the weighted signals are subtracted from the difference signals of the feed array.

Abstract: A baseband generator for pulses of high peak amplitude, rapid rise time, subnanosecond duration, and high pulse repetition frequency is disclosed. A plurality of capacitors are charged in parallel then discharged in series to cause a plurality of avalanche of transistors to fire sequentially. The resulting sum voltage across the capacitors is then applied to a step recovery diode to generate the pulse.

Abstract: A surface wave transmission line enclosed in a dielectric shield and supported within the enclosure at a predetermined distance from the base of the enclosure. The enclosure being constructed such that the surface wave transmission line may be in close proximity to reflecting objects positioned along the enclosure and at a predetermined distance from a mounting structure.

Abstract: A collision avoidance system for rapid transit vehicles employing baseband radar principles in which signals with duration in the order of nanoseconds are transmitted down track along a surface wave transmission line. Reflections from a passive target located on the preceding vehicle are processed to establish the distance between the vehicles to within an accuracy previously unachievable.

Abstract: A continuous, self-supporting microwave transmission line along which ultra short pulses of microwave signals may propagate over distances of several hundred feet with minimum pulse distortion and signal attenuation. Propagation along the line is accomplished by an electromagnetic field thereabout that is sensitive to objects positioned in the proximity of the transmission line, a characteristic that may be utilized in short pulse reflectometer systems for monitoring and control of vehicles on a prescribed course.