Abstract: A ferrite scanning line source is formed of a ferrite toroid and one or more dielectric slabs mounted to a side of the toroid. A signal propagating through the waveguide is phase shifted by the magnetization of the toroid. The further down the toroid the signal propagates the greater the phase shift that is applied to the signal. Radiators or coupling ports are formed by slots cut in a wall of the waveguide. The phase of the signal radiating from each slot in the line source is shifted from the signals emanating from the preceding and following slot in the line source. By properly locating the slots along the line source, a composite beam formed by the energy radiating from each slot may be titled (scanned) to a desired direction. In addition, the amount of phase shift applied to the signal by the waveguide depends on the magnetic state of the phase shifter.

Abstract: A dual band, dual polarized antenna comprising an array of resonators in a plane for radiating at a first frequency, a ring resonator in a plane, the array of resonators being contained within a projection of the boundary of the ring resonator, the ring resonator for radiating at a second frequency which is lower than the first frequency, apparatus for exciting the array of resonators to cause them to radiate at the first frequency with dual polarizations simultaneously, and apparatus for exciting the ring resonator to cause it to radiate at the second frequency with dual polarizations simultaneously.

Abstract: A method of operating a SAR system comprised of emitting a sequence of pulses toward a target, alternating characteristics of pairs of successive pulses, receiving reflected pulses from the target, passing the received reflected pulses through a filter, modifying parameters of the filter in step with the transmitted pulses to match the characteristics of the successive pulses in the event a time delay between pulse transmission and reception of a pulse reflected from a target is a fraction greater than an even multiple of a pulse period, and modifying the parameters of the filter in anti-synchronism with the successive pulses in the event a time delay between pulse transmission and reception of a pulse reflected from a target is less than a fraction greater than an even multiple of a pulse period.

Abstract: The antenna includes an antenna body, comprising a conductive material, having a cavity surrounded by intersecting wall segments. The wall segments include a rear plate and a face plate having a planar array of longitudinal slots, and both plates are positioned in spaced-apart parallel planes. The antenna further includes a center wall, centrally placed between the face plate and the rear plate, to form within the cavity a parallel pair of waveguide channels. The center bar has a center bar opening extending longitudinally along a portion of the center bar, thereby separating the center bar portion into first and second center bar segments. A guidance hole is aligned with an edge of the center bar and extends through the first center bar segment and at least a portion of the second center bar segment. A probe distributes radio frequency (RF) energy in substantially equal phase and amplitude to the waveguide channels via the center bar opening.

Abstract: A method and apparatus for suppressing the generation of passive intermodulation within passive devices. A dielectric sheet comprising dielectric material is placed between first and second conductive elements of the passive device. The second conductive element is then mounted to the first conductive element, thereby "sandwiching" the dielectric sheet between the first and second conductive elements. In this manner, a direct contact connection can not be formed at the junction of the first conductive element and the second conductive element. This absence of a continuous direct contact minimizes the opportunity for passive intermodulation products to be generated at this junction of the passive device.

Abstract: An antenna comprising a waveguide component and a probe assembly, coupled to the antenna assembly, for distributing radio frequency (RF) energy to slots positioned on at least one of the broad walls of the waveguide component. The probe assembly can be positioned at the approximate center point of the waveguide component to present a desired impedance to the waveguide cavity and to distribute RF energy of substantially equal amplitude and phase to each section of the waveguide cavity. The probe assembly includes a post, connected to one or both of the rear and front walls, and a probe pin. The post, which is typically positioned within the center of the waveguide cavity, comprises (1) a post cavity located within and extending along at least a portion of the post, and (2) a post slot having an opening located along the post and traversing the post cavity.

Abstract: An improved spherical gradient lens and a method of fabricating same. A uniform sphere of a material such as high density irradiated polystyrene or a methylpentene copolymer in the polyolefin family having a uniform relative dielectric constant is provided. A plurality of radially extending holes are formed therein, for example by drilling, the holes having a predetermined cross sectional geometry along axes extending radially from the center of the sphere. The geometry of holes is selected to control the resultant local density of material, and thus the relative dielectric constant as a function of distance from the center of the sphere. Hole diameters are chosen so as to be small compared to the shortest wavelength of interest with which the lens will be used.

Abstract: A low loss, fast switching, electronically tunable filter circuit which is microstrip compatible is obtained through the use of a resonant ring structure having two couplers, a low noise amplifier and a variable phase shifter. The tunable filter may advantageously be used in the receive channel of a transmit/receive module for phased arrays wherein the resonant frequency of the ring can be tuned anywhere in the operating frequency range so as to increase the dynamic range of the receiver.