Abstract: A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterized by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature. Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured. A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies.

Abstract: A waveguide for projecting a longitudinal acoustic wave of wavelength .lambda. from an ultrasound energy source toward a target area. The waveguide has at least one tubular channel. The channel has inwardly tapered, conical inlet and outlet ports separated by a venturi. The inlet port taper defines a sharply rimmed entry orifice around the inlet port. A separation distance equal to one wavelength .lambda. is maintained between the source and the waveguide's inlet port. The waveguide shears off a cross-section of the wave emitted by the energy source and ejects it at accelerated velocity toward the target area. The channel has a length L and the venturi has a diameter D, such that the waveguide has an emitted beam angle equal to 2 (tan.sup.-1 (D/L)). Preferably, a plurality of tubular channels are aligned concentrically around and longitudinally parallel to the one tubular channel, each channel having a selected length and a selected diameter.

Abstract: In a piezoelectric resonator having a piezoelectric bar formed in a substantial rectangular parallelopiped and electrodes formed on a pair of confronting surfaces of the piezoelectric bar for resonating in the length expander mode, the piezoelectric bar has at least a bevel portion extending the longitudinal direction. In a ladder filter having series and parallel piezoelectric resonators, the series piezoelectric resonator has the bevel portion to shift a frequency of a spurious response to that of the parallel piezoelectric resonator to suppress the spurious response. It is disclosed that a second piezoelectric resonator has a piezoelectric bar formed in a rectangular parallelopiped has a length L, a width W, and a thickness T wherein L>W>T; and electrodes formed on a pair of confronting surfaces defined by L and T. Another ladder filter includes the second piezoelectric resonator as the series resonator to decrease a capacitance between the electrodes to increase an amount of attenuation.

Abstract: In a surface acoustic wave filter utilizing at least two longitudinal modes, input and output interdigital transducers are mounted on a piezoelectric substrate so as to oppose each other. First and second grating reflectors are mounted on the piezoelectric substrate outside the input and the output interdigital transducers, respectively. Each of the input and the output interdigital transducers comprises a plurality of electrode digits which are equal to N in number. Each of the electrode digits is made of a metal material having a discontinuous impedance coefficient K related to acoustic impedance. The surface acoustic wave filter is structured so that a product of the number N and the discontinuous impedance coefficient K is not smaller than 0.55.

Abstract: A modified branch line coupler amplitude equalizer circuit employing cross arms and branch lines of varying lengths and impedances to minimize the return loss of the circuit.

Abstract: A surface acoustic wave device for generating an output signal with only a symmetric or only an asymmetric vibration acoustic wave mode in a piezoelectric substrate. The device has first and second transversely spaced transducers and the device is driven from both the first and second transducers. A third transducer is between and acoustically coupled to the first two transducers. The electrodes of all three transducers are arranged with respect to each other so as to cause only a symmetrical acoustic vibration mode or only an asymmetrical acoustic vibration mode in the piezoelectric substrate.

Abstract: A two-pole monolithic piezoelectric filter (50) provides an improved frequency response at specified frequencies above the center frequency of a two-pole filter; at these frequencies the frequency response exceeds the attenuation of a four-pole filter without any increase in space, volume, or cost by the inclusion of additional resonator stages (64 and 68) formed into the substrate (52). Appropriate selection of the dimensions of these resonator stages can be used to adjust the frequency at which these resonator stages provide additional desired attenuation.

Abstract: A tri-phase combiner/splitter system that has similar advantages to presently available binary combiner/splitter systems which uses quadrature couplers. Notably, the combiner input Voltage Standing Wave Ratio ("VSWR") remains at 1:1 for identical mismatch impedance at the output ports. There is also a complete cancellation of back-door intermodulation components for identical output device nonlinearities. An innovative wideband, 0.degree. three way combiner/splitter is the basic building block of the present invention. To achieve equal port impedances, a new wideband transmission line transformer is used. By using 60.degree. or 120.degree. phase equalization networks at the three, 0.degree. output ports, this device is converted to a wideband tri-phase combiner.For moderate bandwidths, a coupled transmission line version is possible using meandering strip lines in the same fashion used in quadrature coupler design.