Abstract: A surface acoustic wave device includes a substrate which supports surface acoustic wave propagation having a predetermined surface acoustic wave velocity characteristic and a pair of interdigitated transducers coupled to said surface wave propagation surface. The pair of interdigitated transducers are spaced by a region of said surface wave propagation surface. To adjust the surface wave velocity characteristic of said surface wave device, a thin layer of a nonconducting elastic material, such as aluminum oxide or zinc sulfide is deposited onto a portion of the region disposed between the pair of interdigitated transducers, to change the surface wave velocity characteristic of the surface wave device.

Abstract: A delay line with multiple taps is provided in which a hyperbolically tapered input transducer directs a wave to a plurality of hyperbolically tapered partial reflectors. A plurality of hyperbolically tapered output transducer taps are aligned with each of the partial reflectors so that varying delays may be obtained over a wide frequency band.

Abstract: A surface acoustic wave device includes a semiconductor substrate, a piezoelectric film disposed on the semiconductor substrate, at least one pair of comb-shaped electrodes constituting an input transducer and an output transducer, a plurality of surface acoustic wave filters having different bands which include a plurality of metal electrodes, so disposed that each of them is located between the input and output comb-shaped electrodes of each of the surface, acoustic wave filters, a bias voltage applying arrangement for applying bias voltages to each of the metal electrodes; and a bias voltage regulating arrangement for regulating the bias voltages.

Abstract: An electronic article surveillance and identification system employing a transceiver (10,11) for broadcasting an interrogation signal into a zone to track the location and movement therein of inventory, merchandise, vehicles, animals, people and objects carrying passive (unpowered) transponder tags (12) adapted to receive the interrogation signal, process the signal in an encoded surface acoustic wave device (15) having a predetermined pattern of reflection groove or grating transducers (30-39, 40-72) and echo an encoded response signal to the transceiver.

Abstract: A cathode ray tube for use in a touch panel system that is capable of recognizing touch positions along a coordinate axis of a touch display surface of the system has a flat glass faceplate capable of propegating surface acoustic waves. An input surface wave transducer, acoustically coupled to the touch display surface, serves to launch a burst of surface waves on that surface. At least one array of wave reflective elements are disposed in or on the touch display surface for directing the surface waves derived from the input trasnducer across the touch display surface.

Abstract: A reflective array surface acoustic wave signal compressor or expander (RAC) has a piezoelectric substrate (LiNbO.sub.3) upon which is deposited an input transducer and an output transducer and etched therein a reflective grating. The RAC grating comprises reflective elements which includes a plurality of grooves having either uniform depths and lengths and preselected widths or uniform depths, lengths and widths for producing a flat pass band or a desired frequency characteristic. Yields are increased owing to the simplified fabrication process and costs decreased owing to batch fabrication made possible by the resulting simplified fabrication-process.

Abstract: A single mode waveguide dispersive surface acoustic wave (SAW) delay line is formed by aligning an elongated input transducer, which has a pattern of interdigital electrode fingers which launches a wideband SAW, with a beam compressor that feeds an input waveguide. The input SAW passes down the waveguide to a 3 dB coupler which extracts one-half of the power of the incoming SAW and feeds it in the direction opposite to the input wave. Both portions of the SAW are passed to dispersive reflective arrays along a folded path. A series of additional couplers and reflective dispersive arrays that form the folded path serve to further delay the SAW until it reaches a beam expander at the output end which feeds the SAW to an output transducer that is constructed in a manner similar or analogous to the input transducer.

Abstract: A surface acoustic wave device in which the two ports of an input transducer (2) provided on a piezoelectric substrate (1) are coupled to the two ports of an output transducer (3) via respective reflective multi-strip couplers (12, 13). In order to avoid the necessity of providing external tuned matching components to attain the low potential insertion loss of such a device, the number of electrodes and center-to-center distances of the electrodes of at least one of the transducers are chosen so that the impedance of that transducer is substantially real for a range of frequencies which contains the center-frequency of the device response characteristic as determined by the couplers.

Abstract: A surface acoustic wave (SAW) device comprises a piezo-electric surface acoustic substrate, and plural sets of input/output interdigital electrodes disposed on the substrate. A phase shifter is provided between a sending electrode and a reflecting electrode included in the input or output interdigital electrodes for producing an electrical phase difference to implement a unidirectional electrode. The sending electrode and the reflecting electrode are mutually connected through the phase shifter including two pure reactance elements serially connected between the sending and the reflecting electrodes and a pure reactance element connected to the junction between the two serially connected reactance elements so as to form a T-circuit. When the two serially connected pure reactance elements are selected equal to each other, the operating frequency band is broadened. The phase shifter includes no ohmic resistance and thus is lossless.

Abstract: A surface wave filter is provided with digital structures formed of strip-shaped coatings which are photolithographically produced. The digital structures have groups allocated to them which are also formed of strip-shaped coatings and which follow a respective digital structure. By use of such groups, which do not produce interfering reflections, a level exposure during formation of the digital structures is achieved.

Abstract: In a surface acoustic wave device including launching and receiving transducers (2, 3) and a reflective multistrip coupler (4), the inner boundaries of the input and output electrode arrays (5, 6) of the reflective coupler (4) are defined both electrically and acoustically by an electrically discontinuous strip (23) formed for example by isolated islands of metalization (24) in conjunction with corresponding adjacent portions of interconnecting conductors (16). This enables the effective apertures of the input and output arrays (5, 6) to be better matched to the transducers (2, 3). The arrangement can reduce the insertion loss in low-loss SAW devices (i.e. in which both ends of the transducers (2, 3) are coupled via corresponding reflective couplers (4)) and also in single symmetrical guided mode SAW devices in which the strip 23 can provide an effective inner guiding bus bar whose surface mass loading corresponds to that of the outer bus bars (9, 10).

Abstract: In a surface acoustic wave device which includes a relfective multistrip coupler (4, 4'), direct electrical breakthrough resulting from the adjacent location of the input and output transducers (2, 3) is reduced by including at least one forward multistrip coupler (24,25) in each path coupling the transducers (2,3) via the reflective couplers (4,4') so as to space the transducers (2,3) from one another. In a so-called low-loss device in which both ends of the transducers (2,3) are reflectively coupled, the arrangement enables the input/output track separation (23) of the reflective couplers to be reduced thereby significantly reducing the insertion loss of the device.

Abstract: A surface acoustic wave device includes a plurality of surface acoustic wave elements provided on a piezoelectric substrate. The device further includes a metal electrode provided on the piezoelectric substrate between and around the respective elements, and a bias voltage is supplied to the metal electrode to cause local attenuation.

Abstract: Compensation for the effects of environmentally caused changes and aging on piezoelectric acoustic wave devices is electrically provided by the application of a signal, such as a DC bias voltage, to the finger elements of an interdigital transducer formed on the surface of the acoustic wave device. This produces very large field concentrations at the finger edges which act to magnify the electric field and accordingly the electroacoustic effect which alters the acoustic velocity of surface acoustic waves, shallow bulk acoustic waves and reflected bulk acoustic waves propagating in a piezoelectric substrate between input and output interdigital transducers.

Abstract: An acoustic surface wave device is configured as a bandstop filter. The device has groups of sinusoidal corrugations cut into the top surface of a piezoelectric substrate between the input and output sets of interdigital transducers. The groups of corrugations selectively scatter certain surface acoustic wave spectral components traveling between the input and output transducers. The scattered components are converted to bulk vibration and do not impinge upon the output transducer; other components travel from input to output transducer relatively undiminished. Thus, a band of scattered surface acoustic spectral components is filtered from the input spectrum.

Abstract: A dispersive Surface Wave Acoustic (SAW) filter is provided by a dispersive reflective array, and input and output transducers that we aligned with respect to the array so that the angle of incidence of a SAW from the input transducer is approximately equal to the angle of reflection from the reflective array over the entire range of the dispersive array, wherein the transducers are constructed to provide a frequency response which is matched to the periodicity of the dispersive array. Such design may be accomplished by forming the transducers with hyperbolically curved electrode fingers. The transducers may consist of relatively narrower inner electrode fingers and relatively wider outer electrode fingers. The transducers may also be divided into a plurality of tracks with each of the tracks being subdivided into a plurality of subtransducer elements which are capacitively coupled in electrical series.

Abstract: A surface acoustic wave (SAW) meander type delay line (FIG. 8) is provided by a plurality of multistrip reflecting track changers (82, 84, 86, 88, 89) on a piezoelectric substrate (80) for folding back a SAW propagation path (106, 108) in serpentine manner. The meander delay line is tapped by simple RF tap means comprising single lossless coupling strips (110, 112) in the track changers removing only that portion of the SAW signal actually tapped out and converted to RF, and directly coupling out such signal portion over the entire bandwidth of the track changer. The single strips are on the center line between the arms of respective U-shaped multistrip couplers (102, 104) of the track changers. The structure enables high impedance direct RF multitap bus connection facilitating RF bus summation of many taps without a plural switching network.

Abstract: In devices comprising closely spaced metallized regions deposited upon a dielectric substrate, in particular acoustic wave devices, electric fields may arise between the regions due to pyroelectric effects or acquired static charges during production or subsequently. These fields can cause damage by arcing or cracking of the substrate. The present method overcomes this problem by providing resistive links between such regions so that the fields do not arise. Preferably the links are of metallizing formed simultaneously with the metallized regions. Application to a SAW convolver is described in which the links are strips of metallizing (7,8,9).

Abstract: A surface acoustic wave resonator filter comprises reflector structures whose metallization strips are repeatedly interrupted in length, whereby the arrangement of the interruptions for the individual strips corresponds to a randon distribution.

Abstract: A surface acoustic wave device in a piezoelectric medium includes input and output transducers for launching and detecting a surface acoustic wave along the piezoelectric medium. The device is arranged in a ring loop to process the bidirectional acoustic wave launched from the input transducer. Multistrip couplers in the ring loop between the input and output transducers are used to achieve low loss characteristics. A phase shift introduced by the multistrip couplers between portions of the surface acoustic wave is used to cancel triple-transit reflections.

Abstract: Dynamic variation of the functional properties of a surface acoustic wave (SAW) device is achieved by using photoconductive material on a wave propagating substrate and illuminating the material with changing light patterns. Photoconductive materials, such as lead sulfide or cadmium sulfide, are used that are essentially dielectrics and have substantially no effect on SAW propagation when not illuminated, but under suitable levels of illumination become resistive and interact with the electric fields of the waves to dissipate energy as heat. Scanning control of the areas of illumination may be used to attenuate sidelobes and scattering in a wideband system, while intensity variations may be used to amplitude modulate the waves.

Abstract: An electronics component operating with reflected acoustic waves having a division of weighted reflector fingers into respective sequences of sub-pieces which have a weighting offset relative to one another. A continuation of the fingers extending beyond a principal path is provided by additional, weighted sub-pieces. The additional weighted sub-pieces are at least a fundamental repetition of the sequence of sub-pieces of the corresponding weighted finger of the principal path. The additional sub-pieces are provided in view of distortions which occur causing the waves to follow a path which laterally deviates from the principal path.

Abstract: An acoustic surface wave device is configured as a bandpass filter. The device has similar groups of sinusoidal corrugations cut into portions of both the top and bottom surfaces of an otherwise flat piezoelectric substrate. A pair of input interdigital transducers is located upon one end of the top flat surface of the substrate. A similar pair of output interdigital transducers is located on the bottom flat surface of the substrate at the end opposite the input interdigital transducers. When an input RF spectral signal is applied to the input interdigital transducers, the transducers convert the electrical signal spectrum to a surface acoustic wave spectrum. When the surface acoustic wave spectrum strikes the corrugations cut into the top surface of the substrate, the corrugations selectively scatter certain spectral components into bulk vibration.

Abstract: A surface acoustic wave device is provided for sensing the presence of chemical agents by chemo-electronic means. The device includes a quartz substrate and means deposited on the substrate for propagating and receiving surface acoustic waves along the surface of the substrate. Regions are provided on the substrate containing etched tunnels, the walls of the etched tunnel being coated within with a chemical substance sensitive to the chemical agent to be detected. When surface acoustic waves are caused to pass over these regions, the reaction of the chemical agent to be detected with the chemical substance causes a change in the acoustic wave velocity.

Abstract: An improvement to the reflective multistrip coupler of the surface acoustic wave device described in EPA No. 0098661 for overcoming the k-determined bandwidth limitation wherein, instead of being uniform, the electrode spacing is varied correspondingly along the input and output arrays of the coupler with the result that different frequency bands will be reflected by different groups of electrodes. At least two reflective couplers (24, 25) with complementary spacing variations are included in the path coupling the input and output transducers (2, 3) so that all frequencies in the overall passband have substantially the same overall time delay. Contiguous bands of frequencies f.sub.1, f.sub.2, f.sub.3, f.sub.4 may be reflected by individual related groups 26, 27, 28, 29 of uniformly spaced electrodes forming either a monotonic or a permutated sequence, or the spacing can be varied continuously and monotonically.

Abstract: A low insertion loss surface acoustic wave filter in which withdrawal weighted launching and output transducers 20, 40 are acoustically coupled by two high efficiency reflective multistrip couplers 6, 6'. To reduce the insertion loss, the inner bus bars 21, 41 are reduced in width so as to reduce the dead space 12 in the coupler. This makes it impossible to form a reliable wire bond connection to the inner bus bars which are therefore connected via a conducting path across the propagation path at the ends of the transducers. Further reduction in the widths of the inner bus bars and consequent increase in resistive losses are offset by several connections to a further bus 23, 43 via groups 25 of dummy electrodes arranged at null points in the weighting pattern.

Abstract: An acoustic surface wave device employing an input and an output transducer (2, 3) and a multistrip coupler (5). The input and output tracks (11, 12) are separated to avoid unwanted acoustic energy transfer. As a result, a significant loss can occur from the launching of acoustic energy from the interconnecting conductors of the msc. The interconnecting conductors (22, 32') of the multistrip coupler are spaced differently from the, or the equivalent, wide-aperture beam spacing of conductors (16, 17; 36', 37') in either track of the msc so as not to launch any acoustic surface or bulk waves within the frequency passband. In a forward transfer msc different spacings can alternate, and in a reflective msc the spacing can take the mean of the respective equivalent wide-aperture-beam spacings of the coupler electrodes.

Abstract: A surface acoustic wave device comprising a first set of interdigital electrodes that generate surface acoustic waves, a second set of interdigital electrodes that receive and convert surface acoustic waves into electrical signals, and an intermediate electromechanical coupling element provided therebetween. The coupling element comprises a plurality of parallel strips formed on the surface of a piezoelectric substrate such as to receive and change the direction of propagation of the surface acoustic waves, each of these parallel strips being spaced at a predetermined distance from each other and connected therebetween in a given manner to obtain suitable stopband characteristics.

Abstract: A component has a reflector structure with fingers which are weighted by division into sub-fingers in a longitudinal direction. These sub-fingers are offset relative to one another in a wave propagation direction by a dimension of the weighting.

Abstract: An acoustic surface wave device having a pair of attenuating transducers positioned between the input transducer and the output transducer. Each attenuating transducer has two sets of interleaved electrodes which are connected together by a thin film resistor. The attenuating transducers are spaced apart so that their reflected signals are 180.degree. out of phase, and thus tend to cancel each other. The attenuating transducer arrangement increases the insertion loss of the device and consequently suppresses triple transit signals in the device.

Abstract: An acoustic surface wave device having an acoustic energy absorber of acoustic surface wave absorbing material positioned between the input transducer and the output transducer. The acoustic energy absorber increases the insertion loss of the device and consequently suppresses triple transit signals in the device.

Abstract: An acoustic surface wave device comprising a piezoelectric substrate provided with an input transducer (2), an output transducer (4) and a compact reflective multistrip coupler (6) in which the strips of each pair of comparatively widely spaced strips (7 or 8) in one array of mutually parallel strips are connected to respective strips of a pair of comparatively narrowly spaced strips (8 or 7) in the other array. The wide and narrow spacings alternate along each array. The improvement provides further electrodes 9 located in the relatively wide spaces in each array and electrically interconnected so as to effect a transfer of signal currents along each array and from one array to the other. The device improves efficiency, reduces insertion loss and improves the shape of the pass band.

Abstract: An acoustic surface wave device comprising a piezoelectric substrate provided with an input transducer (2), an output transducer (4) and a compact reflective multistrip coupler (6) in which the strips of each pair of comparatively widely spaced strips (7 or 8)in one array of mutually parallel strips are connected to respective strips of a pair of comparatively narrowly spaced strips (8 or 7) in the other array. The wide and narrow spacings alternate along each array. The improvement provides further electrodes (9) located in the relatively wide spaces in each array and electrically interconnected so as to effect a transfer of signal currents along each array and from one array to the other. The device improves efficiency, reduces insertion loss and improves the shape of the pass band.

Abstract: Electronic components which operate with acoustic waves are provided as interdigital structures and/or reflective arrangements. An oscillating displacement of the significant plurality of sub-groups is provided parallel to the principal axis of propagation in a weighted region, each sub-group having at least two successive real finger edges and, under certain conditions, virtual finger edges. A plurality of principal groups is provided and in a number which is equal to or greater than the time/bandwidth product. Each principal group has at least two real sub-groups and the respective degree of displacement of the finger edges of the individual sub-group corresponds to an additional oscillating phase modulation for the sequence of the sub-groups of the weighted region with the oscillation being such that the number of oscillations within a principal group is a whole number which is not greater than half the number of the sub-groups therein.

Abstract: A dispersive acoustic delay line using reflection on slanted gratings is provided. This device comprises slanting input and output transducers each formed of pair electrode fingers. The interval of the electrodes of different polarity varying from nv/2f.sub.min to nv/2f.sub.max, where v is the speed of the waves, f.sub.min and f.sub.max the endmost frequencies of the frequency band and n the number of the harmonic on which the transducers operate. The interval of the gratings varies from kv/f.sub.min to kv/f.sub.max, where k is the number of the operating harmonic of the network, with n.noteq.k.

Abstract: A surface acoustic wave (SAW) filter partially coated with an acoustical wax, such as one soluble in trichlorethylene, or with an epoxy paint dramatically improves the performance of the filter, especially with regard to the attenuation of out-of-band signals.The coating pattern may be initially empirically determined depending on the substrate and transducer configuration but once determined is readily amenable to known printing and stamping techniques.

Abstract: A novel technique for fabrication of a new class of surface acoustic wave (SAW) signal processing devices. Substrates of non-piezoelectric silicon or weakly piezoelectric gallium arsenide are prepared and a thin film of a piezoelectric material, such as zinc oxide, is deposited on the substrate. Interdigital transducers are fabricated at each end of the device to inject/receive SAW signals. A row of P-N diodes is constructed in the substrate underneath the SAW beam path and a metal electrode is deposited on top of the zinc oxide film. The diodes may be serially addressed/controlled by a variety of devices external to the SAW beam path, but fabricated on the same substrate and the new device used to provide transformation between high-frequency signals and low-frequency signals having the same time-bandwidth product.

Abstract: A surface acoustic wave filter which comprises a substrate of piezoelectric material and a multistrip coupler. The multistrip coupler comprises a plurality of parallel conductive strips formed on the substrate; at least one input transducer is disposed on one side of the multistrip coupler, and at least one output transducer is disposed on the other side of the multistrip coupler. The surface acoustic wave filter is characterized in that a part of the middle portion of each of the conductive strips of the multistrip coupler is made of a photoconductive material.

Abstract: In devices comprising closely spaced metallized regions deposited upon a dielectric substrate, in particular acoustic wave devices, electric fields may arise between the regions due to pyroelectic effects or acquired static charges during production or subsequently. These fields can cause damage by arcing or cracking of the substrate. The present method overcomes this problem by providing resistive links between such regions so that the fields do not arise. Preferably the links are of metallizing formed simultaneously with the metallized regions. Application to a SAW convolver is described in which the links are strips of metallizing (7,8,9).

Abstract: A pulse compression filter designed as a dispersive delay line functions with acoustic waves having a mean wavelength .lambda..sub.o in the filter. At least one input/output transducer or at least one reflector arrangement is provided with a plurality of electrode respectively reflector fingers distributed on a substrate in accordance with a prescribed transfer function which has a given bandwidth and whose Fourier transform has a given time duration T. Said fingers are divided into a plurality of N finger groups designed identical to one another with respect to the number fingers n and corresponding finger spacings of corresponding fingers. Each finger group has a length in a propagation direction of the acoustic wave in the filter which is at least equal to the mean wavelength .lambda..sub.o. Center spacings of adjacent finger groups from one another are non-equidistant in accordance with the prescribed transfer function.

Abstract: An acoustic surface wave multiplexing filter is described having two signal processing paths, one for each of two possible input signals. Each processing path includes an input transducer, a multistrip coupler, and an output transducer. To save substrate area, the multistrip couplers are formed on the substrate in a position of side-by-side overlap with each other.

Abstract: A magnetostatic wave device in which waves propagate in a layer of magnetic material grown on a non-magnetic crystalline substrate with a grating arranged in the wave path for modifying propagation velocity. The grating is formed by ion implantation without removal of magnetic material so coupling with spin modes is avoided.

Abstract: A surface acoustic wave (SAW) device is disclosed. The SAW device includes input and output transducers disposed in spaced acoustic tracks on a piezoelectric substrate material, and a multi-strip coupler for translating the acoustic beam generated by the input transducer into the acoustic track in which the output transducer is located. The multi-strip coupler is designed so as to minimize the influence of Fresnel peaks found to exist in the amplitude profile of the acoustic beam in the output acoustic track. The multi-strip coupler is longer than in the past, and includes a central fanned region for providing well defined acoustic boundaries whose locations do not vary from device to device.

Abstract: A thin film metallic loop is used to electrically short the gap between metallic portions of a surface acoustic wave device to eliminate substrate surface cracks. The loop is deposited on the substrate at the same time the structures defining the gap are deposited.

Abstract: A variable delay line for surface acoustic waves includes spaced input and output transducers affixed on the wave-propagating surface of a piezoelectric substrate for sending and receiving acoustic waves. An AC or DC voltage is applied to the substrate through a pair of electrodes as a strain inducing signal. The applied voltage changes the time delay of the wave by physically altering the length of the propagation path, and/or by altering the effective properties of the substrate to vary the propagation velocity of the wave. The time delay will vary proportionately in response to the applied voltage.

Abstract: In order to suppress triple transit ghost images in a T.V. receiver, a surface wave acoustic filter is provided in which either the input or output transducer system, or both, includes both primary and dummy transducers, the echoes from which cancel each other totally. The dummy transducer is designed as a function not only of position along the acoustic beam path, but also as a function of the number of elemental transducers and their interdigitated lengths; and the design also takes into account relevant electrical parameters including transducer admittances and any external or parasitic impedances under short circuit and open circuit conditions. These factors are taken into account not only for the primary transducer, but also for the dummy transducer.

Abstract: A convolver based on the propagation of acoustic waves at the surface of a piezoelectric solid comprises a piezoelectric substrate, means for exciting two backward-traveling acoustic waves at the frequency f, means consisting of at least two electrodes for collecting the signal at the frequency 2f, the signal being produced as a result of nonlinear interaction of the two acoustic waves. The convolver device is connected to one of the two electrodes by means of a plurality of electrical contacts placed lengthwise and at intervals along the axis of propagation of the two interacting acoustic waves which are representative of the electrical signals applied to the two convolver inputs.

Abstract: An acoustic surface wave device is disclosed for generating an output signal that is the phase-conjugate of the input signal to the device. Disposed on the piezoelectric substrate is a first interdigital transducer for receiving a modulated input signal having a carrier center frequency f.sub.1 and for converting the input signal to an input acoustic wave. A semiconductor material is disposed over the surface of the piezoelectric substrate. A second interdigital transducer is disposed on the surface of the piezoelectric substrate between the first interdigital transducer and the semiconductor material. A standing wave at frequency f.sub.1 is generated by counterpropagating pump waves in the nonlinear acoustic wave interaction region in the area of the semiconductor material.

Abstract: A surface wave acoustic filter is compensated for diffraction and other spurious effects, which distort its frequency response, by adding an auxiliary acoustic channel which is in parallel with the primary acoustic channel, is out of phase therewith, and mimics the frequency response of the primary channel to the diffracted or other spurious wave.

Abstract: Acoustic surface wave devices of a novel class characterized by the provision of coupling means comprising at least several spaced filamentary electrical conductors extending over a first region and a second region for causing acoustic surface waves propagated across the coupling means in the first region to interact with acoustic surface waves propagated across the coupling means in the second region, by means of alternating electric signals induced on the filamentary electric conductors. The regions to be coupled are preferably formed on piezoelectric material, but modified forms of the coupling means can be made operable with other materials and suitable biassing fields.