Abstract: A temperature compensating circuit for a varactor diode having a voltage source applied to a temperature compensating diode which is provided separately from a control voltage for controlling the varactor diode and which is unaffected by a varactor diode controlling voltage source exhibiting a high impedance.

Abstract: Phase quantization errors in a phased array antenna are reduced by providing phase control signals which approximate ideal phase functions for symmetrical pairs of elements having an average phase value which is displaced from a nominal phase quantization value by one-quarter the smallest phase step.

Abstract: A phased array antenna includes a coupling network which is arranged to supply signals to pairs of elements located on opposite sides of the array center with a phase difference which is an odd-integral multiple of one-half the smallest phase step of the array phase shifters. This coupling network arrangement reduces antenna beam pointing errors which arise from a phase quantization of the array phase shifters.

Abstract: The multiple beam, short wave planar antenna array system, which simultaneously exhibits low loss, low side lobe levels, high efficiency, and low volume in a design affording independent control of the E and H plane radiation pattern shapes is particularly applicable in microwave radiometric systems such as airborne mapping systems. The antenna system generates symmetrical, matching narrow pencil beam sensitivity patterns by using symmetrically spaced sectorial receiver horns fed energy through a hyperbolic dielectric lens, the horn array and lens residing in a TE.sub.01 mode parallel plate guide, the lens being illuminated by signals collected by a broad wall slotted wave guide array supplied with a thin, planar sheet radome mounted on the energy receiving face of the array.

Abstract: A digital channel selecting apparatus for selecting a channel among a plurality of channels which are distributed in at least a relatively higher and lower frequency regions, wherein a plurality of capacitance elements are coupled in parallel, each constituting a portion of a tuning circuit, such that each capacitance element is individually coupled to a corresponding switching device which is operable responsive to a digital control signal, whereby the total capacitance value associated with the tuning circuit is varied to achieve channel selection, characterized in that a fixed reactance component, such as a fixed inductance component or a fixed capacitance component commonly coupled to said plurality of capacitance elements for constituting the tuning circuit is selectively switched to a different reactance value in a semifixed manner by means of a switching diode for each of the higher and lower frequency regions.

Abstract: One of ports of a 3dB hybrid for dividing and combining electromagnetic waves is used as an input port, and first and second resonators are electromagnetically coupled respectively with two ports to which the electromagnetic waves incident from the input port are outputted after being divided. The first and second resonators respectively comprise pluralities of opposed coupling disks sequentially arranged in the direction of travel of the electromagnetic waves and first and second reflectors disposed opposite the coupling disks farthest from the hybrid. The numbers of coupling disks of the first and second resonators are selected to differ by one. The remaining port of the hybrid is used as an output port.

Abstract: In accordance with the present invention, a single shunt feed mechanism, including a single gamma section and a single impedance matching circuit, is employed to enable an antenna tower as an effective radiator in plural wave length bands without having to alter the upper tie point of the gamma section to the antenna tower. In one embodiment, the shunt feed of the invention enables the antenna tower as an effective radiator in either two of the adjacent bands mentioned, namely the 40 and 80 meter bands or the 80 and 160 meter bands. In accordance with another embodiment of the invention, a single shunt feed mechanism, including a single gamma section, a single impedance matching circuit, and a filter, enables an antenna tower as an effective radiator in all three of the indicated bands.

Abstract: An antenna mounting structure, for mounting an antenna on a mounting surface with a limited amount of under space, has a coaxial cable attached substantially at a right angle to the axial direction of the mounting structure. The mounting structure includes an antenna base assembly having a lower portion disposed beneath the mounting surface. An antenna disposed in the base also projects below the mounting surface into a cavity in the base, and an aperture is provided in the side of the lower portion of the base. The mounting structure also includes a cable mounting assembly having a cable adapter in the form of a plate with an aperture, on which plate the outer lead of the coaxial cable is fixed so that the cable is substantially parallel to the plate at the connection, the inner lead of the cable extending into the aperture. The cable and adapter are dimensioned such that, when assembled with the base, the inner lead projects into the antenna base cavity and can make contact with the antenna.

Abstract: A band rejection coaxial filter for use with a coaxial transmission line, for example, comprises a casing made of a conductive material and having an internal geometry selected to be in a cut off state with respect to the frequency of a signal being transmitted along the coaxial transmission line. The casing is coupled to the coaxial transmission line and a leakage coaxial cable is provided in the casing, so as to be coupled to the coaxial transmission line through the casing. The leakage coaxial cable is formed of a plurality of leakage openings spaced apart from each other a quarter wave length of the resonance frequency of the resonators in the axial direction for allowing for leakage of the transmission signal. A corresponding plurality of dielectric resonators are provided spaced apart a given distance from and faced to the leakage openings, so that a portion of the transmission signal of the frequency determined by the dielectric resonators is trapped.

Abstract: An antenna mount for a retractable antenna has a collapsible spacer to permit the antenna mount to conform to the shape of the surface to which the antenna is mounted. The collapsible spacer has a plurality of cantilever springs formed thereon which permit one end of the spacer to angulate relative to the centerline of the spacer while the spacer collapses in a direction generally parallel to the centerline thereof without significant change in the diameter of the spacer.

Abstract: An interdigital filter comprising a plurality of resonators each comprising a resonant conductor rod coupled to each other in the even and odd modes of a transverse electromagnetic wave, wherein each resonant conductor rod is enclosed with a dielectric material so as to increase the ratio of the odd mode characteristic impedance to the even mode characteristic impedance.

Abstract: Compact, simple, ferromagnetic-filter coupling structures which provide a very high, effective-quality factor Q in the VHF, UHF, and microwave frequency ranges.

Abstract: A mobile antenna includes a radiating element which can be adjusted to an effective length to tune the antenna to a desired operating frequency without changing the physical length of the element. The radiating element is slidably received in a sleeve member positioned within a central bore having a tapered end of progressively decreasing diameter within the antenna base. The radiating element is locked in position by a deformable rim portion of increased diameter on the sleeve which is drawn into the tapered end of the bore and clamped around the radiating element by means of an axially-aligned bolt threaded into the opposite end of the sleeve. The bolt is preferably accessible only when the antenna is removed from its mounting base to discourage tampering with the antenna.

Abstract: Disclosed is a preset plate for a VHF tuner, having a first and a second rotary bodies which are unitarily mounted on a main shaft of the VHF tuner. The first rotary plate has a plurality of coils corresponding to respective channels to be selected and a number of switching contact pieces, while the second rotary body carries a plurality of fine-adjusting screws for getting into and out of the cavities of respective coils for varying the inductance thereof. Stationary contact members are fixed on the frame of the tuner for engaging the successive switching contact pieces as the preset plate is rotated around the axis of the main shaft.

Abstract: Apparatus for generating elevation and azimuth reference signals for use in demodulating a tracking error signal to provide elevation and azimuth error components for use in adjusting the position of a tracking conical scan radar antenna, includes a template ring having a notched periphery and being attached to a rotatable nutator of the antenna such that its peripheral notches are in a predetermined angular phase relationship with a reference position on a feed horn attached on the nutator, during rotation of the feed horn with the nutator. The apparatus further includes an optical transducer and electronic circuitry coupled thereto for producing the reference signals from a signal generated by the transducer in response to rotation of the ring with the nutator. As the ring rotates with the nutator, its notched periphery makes or breaks a photon path between light beam generating and sensing elements of the transducer.

Abstract: A mobile antenna includes a radiating element and an inductance winding for tuning the radiating element for operation on a desired frequency. The inductance winding is supported within the base of the antenna by a core assembly and an overmold layer within which the turns of the winding are partially embedded. The winding is preferably formed with a relatively large diameter and of relatively heavy gauge wire, and the winding support core is preferably formed with a chamber concentric to the winding to improve the electrical efficiency of the winding, and hence the radiating efficiency of the antenna.

Abstract: A corner fed electric microstrip dipole antenna consisting of a thin eleccally conducting, rectangular shaped radiating element formed on one surface of a dielectric substrate, the ground plane being on the opposite surface. The feed point is located at one corner of the antenna element and the input impedance is matched with a matching microstrip transmission feed line connected to the corner of the antenna. The length of the radiating element is greater than the width and determines the resonant frequency along the Y axis (i.e., length dimension) and the width determines the resonant frequency along the Z axis (i.e., width dimension). This antenna is capable of generating linear polarized radiation along the length thereof with minimal cross-polarization when the radiating element width dimension approaches one-quarter waveguide wavelength and less using a single corner fed element and single feed point. Elliptical polarization is also available with the rectangular radiating element.

Abstract: Increased bandwidth, reduced axial ratios and improved beam shape and sidelobe characteristics are achieved with non-uniform diameter helical antennas. The antenna structures are configured to various combinations of tapered diameter and uniform sections. By varying the number of turns, diameters of the helix sections and lengths of the various helix sections, antennas are synthesized to yield specific gain-frequency response characteristics.

Abstract: A building block resonator is fabricated using a single chemically milled copper pattern and two pieces of garnet material to form a quarter-wave transmission line which is shorted at one end. Tuning is achieved with an electromagnet by varying the static magnetic field perpendicular to the resonator which causes the permeability of the garnet material to change. Resonators formed in this manner can be cascaded in any number to form a multi-pole filter. Narrow band UHF filters (0.5 percent 3 dB bandwidth at 225-400 megahertz) can be built in a very compact form. The magnetic tuning field intensities used are above the saturation point of the garnet, and high power level operation devoid of non-linear effects is possible.

Abstract: An improved electronic structure for achieving a frequency offset between two or more YIG devices tuned by a single electro-magnet. The structure does not require different sizes of YIG spheres, different magnet gap spacings, or modified coil windings on the electro-magnet, but relies entirely upon the anisotropy variations of the single crystal structure of the YIG spheres when they are mounted on respective tuning rods on a specific axis and rotated under a variable field for a fixed frequency input.