Abstract: A surface acoustic wave device including a synchronous reflection array disposed in a delay line between the input and output transducers, the synchronous reflection array having a synchronous reflection frequency that distorts the beam profile of propagating surface acoustic wave energy in the delay line so that when the beam profile is amplitude averaged at the output transducer, the transducer output signal has a relatively deep notch in amplitude at the synchronous reflection frequency.

Abstract: In the synchronous detection signals of frequency Fo immersed in a noise, an auxiliary signal is produced having a period 1/2 Fo and in the form of a rectified symmetrical wave, by rectifying a symmetrical wave of period 1/Fo. The signal to be filtered is multiplied by the auxiliary signal and synchronous filtering or synchronous detection on the frequency Fo is performed on the signal obtained after the above-mentioned multiplication. Preferably the auxiliary signal is produced in the form of a rectified sinusoidal wave and a square wave reference signal from which the above-mentioned symmetrical wave is derived, having the period 1/Fo, is also used to control the synchronous detection or the synchronous filtering.

Abstract: Apparatus for convolving acoustic surface waves without dispersion comprising a piezoelectric substrate having surface acoustic waves generated at opposite ends thereof and directed towards an interaction region formed from a semiconductor film deposited thereon. The film is deposited on the substrate at such an angle with respect to the direction of propagation of each of the two acoustic surface waves so that the dispersive components of the wave vectors associated with the surface acoustic waves refracted in the interaction region substantially cancel. Apparatus is also disclosed for substantially eliminating undesired wave reflections in a convolver operating in the degenerate mode wherein a conductive array of electrode fingers is disposed at an angle with respect to the direction of propagation of the acoustic surface waves such that the reflections therefrom are directed away from the paths traversed by said acoustic surface waves.

Abstract: A variable length, digital delay line apparatus utilizing a set of progressively increasing delay devices in conjunction with a set of digitally selectable switching units to vary the delay times over a predetermined delay range.

Abstract: A signal bandpass filter apparatus is disclosed wherein a direct short circuit between input and output is prevented and the loss of the ground reference of the filter is detectable and fail-safe in operation.

Abstract: A bulk wave acoustic wave device with electrodes fabricated on a crystal in the form of arrays each having a plurality of closely spaced electrodes, one array being angularly disposed with respect to the other to provide at least one pair of matching electrodes notwithstanding uncontrolled beam wander within the crystal.

Abstract: A nonlinear delay line correlator and convolver is described which comprises a tapped, piezoelectric surface acoustic wave delay line and an array of series or parallel connected forward biased semiconductor diodes. An interdigital signal transducer is connected to each end of the delay line and voltages are applied to each transducer to generate contra-flowing acoustic strain waves which are radiated toward an interaction region comprising a plurality of equi-spaced weakly coupled interdigital transducers, each transducer being connected to one diode. Nonlinear signal mixing in the diode array is utilized to perform serial product convolution or correlation of the signal modulation applied at the two signal input transducers. Because of the large nonlinearity of semiconductor diodes, insertion loss is relatively low.

Abstract: A bulk acoustic wave delay line including a body of acoustic wave supporting material and having at least one planar surface capable of reversably converting longitudinal wave mode acoustic energy to shear wave mode acoustic energy, the delay line also including at least one transducer for converting electromagnetic wave energy to acoustic wave energy and vice versa for propagating said acoustic wave energy along a path, a major portion of which supports shear wave mode energy and which path is at least partially defined by the mode converting planar surface, the planar surface being treated to increase the attenuation of propagating acoustic wave energy thereat by a predetermined amount, the attenuation provided at said planar surface being relatively frequency independent as compared to the attenuation per unit time of the propagating acoustic wave energy in the delay line body whereby triple transit signal suppression is significantly increased while still maintaining a relatively wide band frequency respo

Abstract: A piezoelectric monolithic crystal filter having shunt trimming capacitors incorporated into the design of the filter as electrode strips at the edges of the crystal element. This eliminates the need to use discrete low value shunt trimming capacitors which generally are of a few pico-farad capacitance and are expensive and introduce objectionable lead inductance which is non-linear with frequency. A means is provided for producing filters which are less expensive and improve performance over conventional filters, particularly at higher frequencies.

Abstract: The invention relates to elastic surface wave resonators and filters. The device in accordance with the invention is based mainly on the selective reflection of the elastic surface waves. It comprises a crystalline substrate in the upper face of which at least one grating of reflective elements is formed by ion implantation for locally altering the regular arrangement of the atoms in the lattice structure of the substrate.

Abstract: Methods for spatially separating ac and dc electric fields in which materials are used having characteristics as dielectrics to the ac fields and as conductors to the dc fields. The apparatus for separating the fields utilizes homogeneous materials of moderate to high resistivity. The method is applied to the separation of fringe fields near the ends of quadrupole mass filters for the purpose of improving the efficiency of ejection and transmission of ions in mass filter devices.

Abstract: There is disclosed a glow discharge device gas mixture consisting essentially of about 20 to 35 percent atoms of argon and about 80 to 65 percent atoms of a xenon-based composition. The mixture is especially beneficial for use in a color phosphor, direct current (dc) gas discharge device because the mixture substantially lowers device operating currents while providing phosphor stimulation. The xenon-based composition consists essentially of about 95 to 100 percent atoms of xenon and about 5 to 0 percent atoms of another component, particularly one or more selected from neon, krypton, nitrogen, helium, and mercury.

Abstract: An acousto-optic device suitable as a correlator, convolution integrator or Fourier transform device. The device comprises a piezoelectric substrate or crystal such as lithium niobate. The substrate is covered by a thin, outer layer having higher index of refraction than the substrate and a thickness on the order of 50 micrometers. Two acoustic transducers such as interdigital transducers are disposed on opposite ends of the crystal to launch two acoustic surface waves in opposite directions. A laser beam is guided through the outer layer and is coupled with the two acoustic waves to generate either a correlation function, a Fourier transform or a convolution integral depending on the signals impressed thereon.

Abstract: An active resonant circuit to be used as a cell for a low insertion loss high level microwave filter is disclosed comprising a circuit tuned at f.sub.o inductively coupled with a negative resistance amplifier consisting of a transistor with a cut-off frequency high with respect to f.sub.o , an emitter circuit coupled to said tuned circuit, with a high transformer ratio, an adjustable tuned circuit in the base of said transistor and means for biassing said transistor for maximum negative resistance at f.sub.o . Two or more cells may be associated to constitute a filter.

Abstract: Two waveguide structures are coupled by connector members that are slideably engaged to one waveguide and adaptable to fixed engagement with the other. Tapered threaded locking pins are threaded through a portion or extension of the waveguide structure that accommodates the slideable end of the connector members. The tapered end of each locking pin engages a tapered recess in a connector member. Longitudinal translation and fixed coupling of the two waveguide structures is achieved by screwing the tapered ends of the locking pins into full registration with the tapered recesses in the connector members. The connector members can be rotatable about the locking pins and partial retraction of the locking pins permits ready disengagement of the connector members from the other waveguide.

Abstract: An elastic surface wave filter is disclosed which is composed of a substrate for the propagation thereon of elastic surface waves and transmitting and receiving transducers, each having at least an electrode deposited on the major surface of the substrate and in which the transmitting and receiving transducers are disposed line connectin the major surface of the substrate a predetermined distance apart from each other; the electrode of one or both of the transmitting and receiving transducers is formed with first and second comb-shaped electrodes; and the first and second electrodes are disposed with each electrode element of the latter extending between adjacent ones of the electrode elements of the former. The electrode elements of the first and/or second comb-shaped electrodes are weighted in terms of length and the extent of the region of overlapping of the first and second comb-shaped electrodes in a first direction, i.e.

Abstract: A notch filter for the selective attenuation of a narrow band of frequencies out of a larger band wherein a helical resonator is connected to an input circuit and an output circuit through discrete and equal capacitors, and a resistor is connected between the input and the output circuits.

Abstract: An electro-mechanical filter is configured from a single thin metal sheet and comprises a base portion, at least four vibratory tines extending outwardly from the base portion, and a plurality of supporting members also extending outwardly from the base portion. The tines and supporting members are arranged circumferentially around the base portion in alternate relationship and extend from the base portion in parallel with each other. The tines may extend in either the same or the opposite direction as the supporting members. A piezo-electric element is coupled to each tine and the elements are differentially connected together to form a filter.

Abstract: An improved miniaturized electro-acoustic surface-wave filter device is disclosed having broad, deep, adjacent channel stopbands from uniform aperture transducers. The device includes two spaced, interdigital electrode transducer structures fabricated on one surface of a piezoelectric substrate. Each electrode structure includes a central finger group and a number of flanking finger groups spaced from the central finger group at predetermined temporal locations. The strengths of the flanking groups are adjusted by controlling the number of finger pairs within a group, the overlap length of the fingers, and the strip/gap ratio of the fingers. Aperture uniformity is maintained in reduced overlap flanking groups through the series weighting technique. The subject device is particularly useful for channel selection in the IF portion of a television receiver.

Abstract: A surface acoustic wave delay line uses a closed loop principle with separate input and output transducers side by side. 3dB Multistrip couplers are introduced to achieve substantially 100% transfer for surface acoustic wave energy from the propagation path associated with the input transducer to the propagation path associated with the output transducer. Several such delay lines can be formed on a single cylindrical body of piezoelectric material and these can then be cascaded with intermediate amplification to form a long delay or a tapped delay.