Abstract: Microwave bandpass filters contain dielectric resonators mounted in dielectric blocks, which are in turn mounted in cavities. There can be more than one dielectric resonator per cavity. Significant size reduction has been achieved over prior art filters. The filters can be operated at cryogenic temperatures and since the results attainable at cryogenic temperatures are repeatable, the filters can be tuned at cryogenic temperatures and returned to room temperature before being returned to cryogenic temperatures for operating purposes. When operated at cryogenic temperatures, the filters contain shorting plates having high temperature superconducting material thereon. The filters can be constructed with various configurations and can be operated in either a single mode or a dual-mode. Previous single mode or dual-mode dielectric resonator filters are larger in size and mass than the filters of the present application.

Abstract: A power divider has a microstripline circuit with bandpass filters at each output that are lumped element printed bandpass filters. The filters widen the isolation bandwidth of the divider. Power dividers can be reversed for use as power combiners.

Abstract: An interdigital transducer for use in a surface acoustic wave filter has two busbars of an irregular shape to reduce the effect of internally reflected surface waves. The busbars will usually have an identical shape to one another and have stepped outer and inner edges. The distance between a portion of the outer edge and a corresponding portion of the inner edge can be constant for a particular busbar or that distance can vary. With previous busbars, the outer and inner edges are linear and each busbar has a rectangular shape.

Abstract: A filterbank using surface acoustic wave technology and having a plurality of filters. Each filter has an input transducer and an output transducer. The input transducers are connected in parallel to a single matching circuit. The output transducers each have a separate matching circuit. The transducers are formed by a thin film of aluminum pattern on a piezoelectric substrate. The input transducers all have the same structure and the output transducers all have the same structure, though that structure is different from the input transducers. The only difference between the transducers of each filter is the location of electrode breaks for each electrode. A weighting function of the transducers is scaled and biased to provide a constant impedance across the bandwidth of the filterbank and to equalize the output amplitudes and capacitances of the output transducers. This produces a continuous level response across the bandwidth of the filterbank.

Abstract: A dual-mode filter has a dielectric resonator in each cavity, with each resonator containing one or more apertures. The aperture or apertures are located to shift a resonance frequency of a spurious mode to a higher frequency range distance from a principal mode. The principal mode can be an HEH.sub.11 mode and the spurious mode can be an HEE.sub.11 mode or vice-versa. The dielectric resonators can be a solid block or two or more discs that are laminated to one another. Previous dual-mode filters cannot attain the results required for current satellite systems.

Abstract: C-, T- and S-switches have a connector or reed in each conducting path. The connector or reed contains a support for a permanent magnet. All of the magnets of the connectors have the same polarity. The connectors, supports and permanent reed magnets in the supports are contained within an RF cavity housing, which can be completely sealed from an actuator or, alternatively, the housing can be open to the actuator. The actuator has a circular shape and contains permanent magnets that correspond in their configuration to the reed magnets of the housing. At least two magnets of the actuator have different polarities. The actuator can be rotated by a motor to two or more positions. In one position, one or more of the reed magnets are attracted and one or more of the reed magnets are repelled. The switch is designed so that when a reed magnet is attracted, the conducting path in which the connector is located is interrupted and when a reed magnet is repelled, the conducting path is connected.

Abstract: A microwave C-, T- or S-switch has an actuator of circular shape that is rotated by a suitable motor. Each conductor path of the switch contains a connector having two positions, one position connecting the conductor path and a second position interrupting the conductor path. The conductor paths and connectors are enclosed within a housing and a pin is mounted on each connector and extends outside of the housing through a suitable opening. Each pin is spring-mounted so that the conductor path is connected when the pin is depressed and interrupted when the pin is released. The actuator is shaped and mounted to override the pins, the actuator containing one or more ridges and one or more indentations. When a ridge overrides a pin, the pin is depressed and the conductor path is connected. When an indentation overrides a pin, the pin is released and the conductor path is interrupted.

Abstract: A microstripline interdigital planar filter has a number of microstripline coupled resonators in an inhomogeneous medium consisting a soft dielectric substrate, and a high dielectric constant, high Q ceramic superstrate. The resonators are printed on the soft substrate as thick copper strips. The rectangular shaped, silver-coated aluminum housing dimensions are chosen so as to give the highest available unloaded Q factor of the resonators. The high dielectric constant of the superstrate is chosen so as to give a very small resonator length resulting in a very small filter size. The input and the output ports are located at right tapping points on the two outermost resonators. The tapping points are chosen so as to match the loaded Q factor of the filter. Previous filters are physically larger and cannot achieve the same high level of performance characteristics as filters of the present invention.

Abstract: A polarizer has a plurality of short waveguide sections arranged so that rectangular-shaped sections alternate with circular-shaped sections. The two end sections are both circular. The rectangular sections have a minimum size at least as large as the minimum diameter of the circular sections. The size of the rectangular sections progressively changes from section to section with all sections of the polarizer being symmetrical about the centre point of the polarizer. The length of each section is less than half a wavelength at maximum operating frequency. The structure of the polarizer is simple and straightforward so that computer-aided analysis and design methods can easily be used. The polarizer has a relatively large bandwidth and can interface directly with corrugated circular waveguides.

Abstract: A two, three or four channel multiplexer can be operated in the TE.sub.01.delta. or HE.sub.11.delta. modes, each channel of the multiplexer has one bandpass filter, with each filter usually having a plurality of cavities. One cavity of each filter is a common cavity with all of the other filters of the multiplexer. The common cavity contains one independent dielectric quarter-cut or half-cut image resonator for each filter representing a channel of the multiplexer. Each resonator is mounted on a suitable support the common cavity provides a common junction and contains a loop coupling to couple electromagnetic energy between the various channels. The multiplexer has at least one input and at least one output. Previous microwave multiplexers have a plurality of bandpass filters arranged on a coaxial manifold. With the multiplexer of the present invention, the manifold can be eliminated.

Abstract: An electronically scanned radar system has a serpentine antenna, with at least two ports. The antenna is physically rotated. Each port has a mixer, transmitter and local oscillator feeding signals to it, the signals of the transmitter and oscillator being synchronized with one another to take advantage of the physical rotation of the antenna. The radar system can be operated in various ways to produce two independent beams simultaneously in a surveillance mode and/or tracking mode at each port. Furthermore, with the use of coupling means, the system can be operated to produce four independent beams at two different frequencies simultaneously. The system can also be operated to produce one or more beams in a surveillance mode and/or one or more beams in a tracking mode at each port. Further, the system can be operated to compensate for the physical rotation of the antenna and can avoid jammers by hopping to another frequency.

Abstract: An electronically scanned radiometer has a dispersive serpentine antenna with one or two ports. A mixer is connected to each port with each mixer being fed by a variable frequency local oscillator. Each oscillator provides the mixer to which it is connected with a drive signal that varies in frequency. The antenna most efficiently receives one or more beams through radiators at an angle that varies with the frequency of the drive signal at the mixer. An output is received at each port and is appropriately displayed. When the serpentine has two ports the radiometer can be operated at two orthogonal polarizations. The frequency being fed to each mixer can be varied in various predetermined patterns. Scanning of the beam can be effected by changing the frequency of observation without physically rotating the antenna. Also two simultaneous beams rotating in opposite directions with independent motions can be achieved.

Abstract: A microwave switch that is an S-switch or a C-switch or the like has an electromagnetic actuator and a plurality of armatures. The armatures moves simultaneously in a linear path in response to the electromagnetic actuator. The actuator has one permanent magnet for each aperture and the switch has at least one coil winding. When an electric current is passed through the winding, the armatures move into a closed or open position, as desired. The only moving parts in the switch are the armatures themselves. The switch does not contain any complex mechanical arrangement or return springs that have been found in previous switches. The mass and volume of the switch as well as the number of moving parts is greatly reduced when compared to previous switches. This is very important when the switch is used in satellites.

Abstract: A dielectrically stabilized planar GaAs FET oscillator has a single gate transistor with a gate terminal and a drain terminal. A cylindrically shaped dielectric resonator is mounted on a ceramic support. The dielectric resonator resonates in a TE.sub.01 mode and is located on the gate line of the transistor a predeterminated distance from the gate terminal. The transistor is biased so that the dielectric resonator alone can stabilize the power produced by the transistor. Stabilized output power is obtained from both the drain terminal and the gate terminal. With previous oscillators having a single gate transistor, output power could only be obtained from one terminal.

Abstract: A reconfigurable beam-forming network for use with a transmitter has a waveguide R-switch that is interconnected with a Magic T. The R-switch contains phasing elements and is connected to a dual-mode power-dividing network, which in turn is connected to first, second and third region power-dividing networks, each having their own feed horn array. The R-switch can be moved to three different positions so that in a first position power is divided between two input ports of the dual-mode network on substantially a fifty-fifty basis with the power on the two input ports being out of phase on a positive basis. In a second position of the R-switch, power is also divided on substantially a fifty-fifty basis between the two input ports but the power is out of phase between the two ports on a negative basis. In a third position of the R-switch, substantially all of the power entering the R-switch is passed into the first input port of the dual-mode network.

Abstract: This invention relates to a modular contiguous channel multiplexer having one or more modules that produce an asymmetric filter function that is combined with responses from other modules to produce an overall symmetrical response. The multiplexer can have channels arranged in any order of relative frequencies and one or more channels can be added or removed from the multiplexer without disturbing the operation of the existing or remaining channels. A method of constructing a multiplexer involves choosing the most downstream channel first, then choosing sequentially the channel immediately upstream from the channel last chosen and choosing filters of each channel to meet certain criteria. The filters of each channel are identical to one another but are not necessarily identical to filters in adjacent channels.

Abstract: A waveguide R-switch has transformers in one or more of its three waveguide paths. The presence of the transformers allows the R-switch to be constructed of a smaller size than previous R-switch with curved outer paths. This results in important weight and volume savings.

Abstract: A quadruple mode bandpass filter has at least one cavity resonating in four independent orthogonal modes simultaneously. Preferably, the filter has two cavities, one cavity being a quadruple mode cavity and the remaining cavity being either a single mode, dual mode, triple mode or quadruple mode cavity. By introducing a resonant feedback coupling into filters of the present invention, the number of transmission zeros produced by the filter is equal to the order of the filter. Previous filters have cavities resonating in either a single, dual or triple mode and the maximum number of transmission zeros is equal to the order of the filter minus two.

Abstract: A fin-line resonance isolator has layers of hexagonal ferrite material that are stacked relative to one another so that the overall length of the isolator remains substantially constant as the number of layers of ferrite material increases. The isolator has substrate materials that are arranged so that the plane of circular polarization is shifted to a center of the isolator. Isolators of the present invention are capable of producing improved responses over prior art isolators while reducing insertion loss and achieving a weight and volume saving.

Abstract: A triple mode dielectric loaded bandpass filter has at least one cavity resonating in three independent orthogonal modes. A triple mode cavity can be mounted adjacent to either single, dual or triple mode cavities. Inter-cavity coupling is achieved through the iris having two separate apertures that together form a T-shape. The cavities can be planar mounted. The filter is designed for use in the satellite communication industry and results in substantial savings in weight and size when compared to previous filters.