Abstract: A surface acoustic wave filter device suitable for CDMA communication system includes a piezoelectric substrate, and a unidirectional input side transducer and a bidirectional output side transducer are formed on the substrate. The filter device has satisfactory filtering characteristics in terms of insertion loss, frequency characteristic, T.T.E. attenuation level, group delay time, etc.

Abstract: In a resonator-type SAW filter, at least one series-arm SAW resonator has an interdigital transducer with reflectors on both sides, and the reflectors are separated from the interdigital transducer by a distance of from (N/2+0.55).lambda..sub.1 to (N/2+0.81).lambda..sub.1, where N is an arbitrary non-negative integer and .lambda..sub.1 is the wavelength of the surface acoustic waves excited by the SAW resonator. Alternatively, from 30% to 80% of the electrode fingers Constituting the interdigital transducer in at least one series-arm SAW resonator are apodized, dividing the interdigital transducer into an excitation region and a dummy region, and the electrode fingers in the dummy region are offset from the electrode fingers in the excitation region by a distance of 0.05.lambda..sub.1 to 0.31.lambda..sub.1.

Abstract: A three-electrode longitudinally-coupled-type SAW resonator filter has an improved level of selectivity by effectively suppressing unwanted large spurious responses generated in a range higher than the pass band. A first ID electrode, a second ID electrode and a third ID electrode are disposed on a piezoelectric substrate. Reflectors are provided on one side of each of the second and third ID electrodes, respectively. A center distance L.sub.1 between the most adjacent electrode fingers of the respective first and second ID electrodes is differentiated from the center distance L.sub.2 between the most adjacent electrode fingers of the respective first and third ID electrodes. Further, the first ID electrode is weighted to more effectively suppress undesired spurious responses.

Abstract: The inside-band characteristic of an internal reflection type unidirectional surface acoustic wave filter is improved by using an internal reflection type unidirectional surface acoustic wave filter having positive and negative finger electrodes (10, 11) of the interdigital transducer and having open or short-circuit type floating electrodes (12) therebetween. The finger electrodes are subjected to weighting by a withdrawal technique and the filter is structured such that at portions wherein no electrical cross is made between the positive and negative finger electrodes, i.e., in case where adjacent finger electrodes each have the same sign as that of the positive finger electrode or negative finger electrode, the floating electrodes (13) located therebetween are not displaced from the center positions therebetween.

Abstract: A surface acoustic wave device includes first and second longitudinal mode resonators. The first longitudinal mode resonator has two resonance modes, i.e., a longitudinal mode distributed in the same direction as a propagating direction of a surface acoustic wave (SAW) and a transverse mode distributed in a direction perpendicular to the propagating direction of the SAW. The second longitudinal mode resonator is arranged adjacent to the first resonator in a direction perpendicular to the propagating direction of the SAW, and has two resonance modes, i.e., a longitudinal mode and a transverse mode. The resonance modes of the second longitudinal mode resonator are acoustically coupled to the resonance modes of the first longitudinal mode resonator. The first longitudinal mode resonator has an output InterDigital Transducer (IDT) having an interdigital electrode to excite a SAW. The second longitudinal mode resonator has an input IDT having an interdigital electrode to receive the SAW from the output IDT.

Abstract: A surface acoustic wave filter is provided which performs balanced signal/unbalanced signal conversion. The input and output impedances are different from each other. In a surface acoustic wave filter of the longitudinal mode type, a signal is applied to two terminals of an input interdigital transducer, or a signal is output from two terminals of an output interdigital transducer, thereby consituting a balanced type filter. The aperture length of the input interdigital transducer is different from that of the output interdigital transducer.

Abstract: A surface acoustic wave filter device suitable for CDMA communication system, includes a piezoelectric substrate, and a unidirectional input side transducer and a bidirectional output side transducer are formed on the substrate. The filter device has satisfactory filtering characteristics in terms of insertion loss, frequency characteristic, T.T.E. attenuation level, group delay time, etc.

Abstract: A dual-function converter, particularly for a dual filter, suitable as a channel filter for double-standard input signals in television sets. Only a single input converter is disposed on the substrate chip, and it has two inputs. The filter configuration of the converter includes interdigital adaptation regions, which are connected in terms of potential to suit whichever of the input signals is selected.

Abstract: A surface acoustic wave device achieving improved insertion loss and fraction defective without lowering the TTE level includes an IDT electrode located on a piezoelectric substrate. The IDT electrode includes a solid electrode portion and a split electrode portion continuously formed at an end of the solid electrode portion in the propagating direction of a surface acoustic wave and having an electrode finger width of about .lambda./8 wherein .lambda. is the wavelength of the surface acoustic wave.

Abstract: Surface acoustic wave (SAW) filter performance is enhanced using series-block weighting and line-width weighting combined for providing a transducer having a finely adjusted uniform weighting across the beam profile. Such a transducer permits practical transducer pairing within a surface acoustic wave filter, as well as use with transducers requiring uniform weighting, such as transducers employing apodized weighting. A three electrode per wavelength transducer electrode finger geometry includes line-width weighting for providing a fine weighting control to complement the inherently coarse weighting control of the series-block weighted transducer. Selected transducer geometries including three electrode per wavelength structures are employed for use in wide band tapered electrode finger SAW devices.

Abstract: A transversal SAW filter capable of reducing the effect of diffraction to achieve desired transmission characteristics without increasing the size of the surface wave substrate includes first and second IDTs arranged on a surface wave substrate so as to be spaced from each other by a predetermined distance. The first IDT has a plurality of impulses and the impulse in the 2n-th (n is a natural number) position counted from an impulse located at a maximum cross length in the 0-th position toward the second IDT has a magnitude which is equal to a magnitude of the (2n-1)-th impulse multiplied by -1.0.

Abstract: A free edge reflective-type surface wave resonator for reflecting SH-type surface waves between two confronting free edges of a piezoelectric substrate includes a piezoelectric substrate having two confronting free edges and an interdigital transducer having a plurality of electrode fingers which are weighted by a cross width weighting method or an electrode thinning method. The weighting of the electrode fingers is performed so that an attenuation pole of a main lobe of the weighted IDT is located outside of a frequency of an attenuation pole of a normal non-weighted IDT which has the same number of electrode finger pairs as the weighted IDT. The weighting of the electrodes is such that the main lobe of the weighted IDT and a plurality of resonance characteristics determined by the attenuation poles of the normal unweighted IDT are obtained.

Abstract: An elastic wave position-sensing device comprising two elastic wave transducing units X and Y, a nonpiezoelectric plate, and a controlling system connected with the units X and Y. Each unit consists of a piezoelectric substrates P.sub.T and P.sub.R, interdigital transducers T.sub.0 and T.sub.i (i=1, 2, . . . , N) formed on one end surface of the piezoelectric substrate P.sub.T, interdigital transducers R.sub.0, R.sub.i1 and R.sub.i2 (i=1, 2, . . . , N) placed on one end surface of the piezoelectric substrate P.sub.R. Each of the interdigital transducers R.sub.i1 and R.sub.i2 is placed such that the finger direction thereof is slanting to that of the interdigital transducer T.sub.i by an angle .alpha.. The thickness d of the piezoelectric substrates P.sub.T and P.sub.R is smaller than an interdigital periodicity P of the interdigital transducers T.sub.0, T.sub.i and R.sub.0. The thickness of the nonpiezoelectric plate is smaller than two times the thickness d, the piezoelectric substrates P.sub.T and P.sub.

Abstract: A SAW resonator for forming a frequency trap has a surface wave substrate and at least one interdigital transducer located on the surface wave substrate. The interdigital transducer includes a pair of comb-shaped electrodes each having a plurality of electrode fingers arranged so that the pair of comb-shaped electrodes interdigitates with each other. An overlapping width of the electrode fingers of the interdigital transducer is set such that in an impedance-frequency characteristic a transverse mode ripple occurring between a resonance point and an antiresonance point is located at the antiresonance point.

Abstract: A full duplex radio (10) having improved properties obtained by using surface acoustic wave (SAW) filters (92, 100, 100') having asymmetric frequency responses (76', 76", 140). The filters (92, 100, 100') are composed of series (50.sub.1, 50.sub.1 ') and parallel (50.sub.2, 50.sub.2 ') coupled SAW resonators. Asymmetry is obtained by altering the metallization thickness of either of the series (50.sub.1, 50.sub.1 ') or parallel (50.sub.2, 50.sub.2 ') resonators of each filter (92, 100, 100') to increase or decrease the SAW coupling coefficient of some of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 ') relative to the remainder of the resonators (50.sub.1, 50.sub.1 ', 50.sub.2, 50.sub.2 '). The filters (92, 100, 100') are desirably in pairs arranged with mirror image frequency asymmetry such that the steeper skirts (93, 95) of the frequency responses (76', 76", 140) are adjacent. Greater passband bandwidths (91', 91") can be obtained without adverse affect on transmitter and receiver isolation.

Abstract: A weighted reflector which has relatively low sensitivity to production-dependent tolerances. The reflector is based on the principle of an open-short reflector which has length-weighted reflector strips.

Abstract: In order to effectively suppress a spurious response appearing at a lower side of a passband of a two-pole type bandpass filter, an overlapped electrode portion of each of interdigital transducers is configured so as to reduce an influence of one standing wave resulting one of three longitudinal resonance modes.

Abstract: The invention relates to a SAW filter comprising a first and second pair of substantially equivalent SAW transducers electrically coupled to form a bridge circuit. Each of the transducers of the first pair of transducers have a center frequency which is slightly different to the center frequency of each of the transducers of the second pair of transducers. The product of the static capacitance of the first pair is the same as the product of the static capacitance of the second pair. In use, signals input to the filter and having a frequency within the passband of the filter are coupled to the output of the bridge circuit via one or other or both arms of the bridge, as in normal bridge circuit operation. However, out of band signals are blocked since all the transducers are equivalent capacitors having the same capacitance (i.e., static capacitance). Thus, transmission of out of band signals through the filter is inhibited by the balanced nature of the bridge.

Abstract: A surface acoustic wave bandpass filter has a piezoelectric substrate for propagation of electroacoustic waves, an input apodized electroacoustic transducer on a surface of the substrate having a tilted apodization structure, an output unapodized electroacoustic transducer spaced from said apodized transducer on the substrate surface and a phase compensator and a shield, which are metal film areas disposed on the surface of the substrate between the apodized and unapodized transducers. The apodized transducer has first and second V-shaped summing bus bars each consisting of a first part arranged in parallel to the direction of propagation of acoustic waves and a second part aligned at an angle .PSI. with respect to the first part, the second bus bar being disposed symmetricaly to the first bus bar relative to the tilted apodization structure.

Abstract: A surface acoustic wave device includes a piezoelectric substrate, an input electrode formed on the substrate and an output electrode formed on the substrate. A surface acoustic wave is generated from the input electrode to propagate in a predetermined direction in accordance with an input signal. In the output electrode, a plurality of taps are arranged in a propagation direction of the surface acoustic wave on the substrate. The surface acoustic wave is converted into an electrical signal by the output electrode. The taps of the output electrode are weighted so that signals output from the taps have substantially equal magnitudes.

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 surface acoustic wave convolver includes first and second interdigital electrodes for exciting surface acoustic waves and an output electrode for detecting the surface acoustic waves to extract a convolution output as an electrical signal, the first and second interdigital electrodes and the output electrode being formed on a piezoelectric or electrostrictive substrate.

Abstract: In an interdigital electrode of a surface acoustic wave device having nonexciting portions formed by removing fingers, fingers having an excitation source located nearest to a nonexciting portion in between are so positioned as to approach the nonexciting portion as compared with arrangement pitch of other fingers. Fingers having an excitation source located nearest to an end of the electrode in between are so positioned as to approach the end of the interdigital electrode as compared with arrangement pitch of other fingers. Fingers having an excitation source located in the central portion of the electrode group in between are so positioned as to approach each other as compared with arrangement pitch of other fingers.

Abstract: In a surface acoustic wave filter having a piezoelectric substrate (11) on which an input interdigital transducer (12) and first and second output interdigital transducers (15, 16) are disposed with the output interdigital transducers opposed to the input interdigital transducer apart therefrom, a first output port (17) for the first output interdigital transducer is directly connected to a filter output terminal (20). Between the filter output terminal and a second output port (18) for the second output interdigital transducer, a switch (22) selectively connects the second output port to the filter output terminal to make the filter output terminal produce a filtered output signal which is equal to a sum of at least one of output electric signals supplied from the first and the second output ports. The switch may be a PIN diode or a mechanical switch.

Abstract: According to this invention, a weighted transducer for a surface acoustic wave filter includes first and second overlap transducer fingers. The first overlap fingers are formed on a surface of a piezoelectric substrate and have overlap widths continuously changed in a propagation direction of a surface acoustic wave. The second overlap transducer fingers are alternately adjacent to the first overlap transducer fingers in a longitudinal direction of the fist overlap transducer fingers, formed on the surface of the piezoelectric substrate to be electrically connected to each other in parallel and reverse-biased, and have overlap widths of the second overlap transducer fingers continuously changed in the propagation direction of the surface acoustic wave. A sum of the overlap widths of the first and second overlap transducer fingers is always set to be constant in the propagation direction of the surface acoustic wave.

Abstract: In a surface acoustic wave transducer including a substrate made of a piezoelectric material, an input side IDT structure having positive and negative electrodes arranged in an interdigit manner and floating electrodes arranged between successive positive and negative electrodes, and an output side IDT structure having positive and negative electrodes arranged in an interdigit manner and floating electrodes arranged between successive positive and negative electrodes, the electrodes of the input and output side IDT structures are arranged such that a surface acoustic wave propagates in one direction, distances between corresponding tracks in the input and output side IDT structures are linearly changed and lengths of these tracks are changed in accordance with a predetermined window function.

Abstract: A surface acoustic wave device comprises a piezoelectric substrate and a plurality of electrode fingers which are located on the piezoelectric substrate along the propagation direction of a surface acoustic wave. The electrode fingers are located on the piezoelectric substrate at a pitch of about 1.5.lambda.o/2 (where a symbol .lambda.o indicates a wavelength of a surface acoustic wave with a frequency equivalent to the center frequency of the surface acoustic wave device). The width of each of the electrode fingers is about 1.5.lambda.o/4. The electrode fingers are located on the substrate so as to be electrically independent of an external circuit and each other.Since the width of electrode fingers is about 1.5.lambda.o/4, the surface acoustic wave device can be produced without fine processing techniques.

Abstract: A surface elastic wave filter includes a plurality of input interdigital transducers for receiving a high-frequency input signal, and a plurality of output inter-digital transducers for producing an output signal derived from the input signal and having predetermined frequency characteristics. Each of the input and output interdigital transducers having a pair of confronting connectors for receiving the input signal and extracting the output signal, respectively, and a pair of groups of interdigitating electrode fingers extending from the connectors. The input and/or output interdigital transducers include finger-withdrawn interdigital transducers with electrode fingers selectively withdrawn in different positions. With such withdrawal weighting, the interdigital transducers have different sidelobe characteristics, i.e., frequency blocking characteristics, so that the surface elastic wave filter operates with a greater sidelobe suppression.

Abstract: Interdigital transducers (3, 4) and reflectors (5, 6) are formed on a piezoelectric substrate (2) by an aluminum film. The aluminum film is crystallographically oriented in a constant direction, whereby stressmigration of the aluminum film is suppressed.

Abstract: An ACT (acoustic charge transport) filter comprises a plurality of SAW (surface acoustic wave) transducers and an interleaved filter bank coupled on either transversal side of the SAW transducer. Each interleaved filter bank comprises two filters, and the electrodes of the two filters are interleaved. Isolation between the interleaved electrodes is supplied by a meadering ground. The electrodes are apodized to facilitate weighted sampling of the delayed signal. Multiple frequency characteristics may be extracted from a single ACT filter by cascading the SAW transducer/interleaved filter bank combinations. Weighted sampling of the delayed signal may also be accomplished through weighted withdrawal of the ACT filter.

Abstract: A surface acoustic electric wave device of the type comprising, over a large face of a planar piezo-electric substrate, a first row of parallel conductive fingers having an individual geometry chosen and distributed according to a chosen distribution arrangement along this row, a second row of parallel conductive fingers having an individual geometry chosen and distributed according to a chosen distribution arrangement along this row, the second row being interspaced from the first so as to allow a propagation of surface acoustic waves between the fingers of the first row and those of the second, which imparts to the device spectral and/or temporal characteristics defined by the acoustic propagation and the frequency selectivity due to the geometry of the fingers.

Abstract: A dispersive surface acoustic wave delay line device consists of a plurality of delay line elements which are disposed parallely so that a propagating path of a delay line element is not co-owned by the other delay line elements, in order to reduce secondary effects caused by electrode fingers.

Abstract: A SAW (surface acoustic wave) device tapped delay line comprises a continuous pattern of bifurcated inter-digital fingers having a constant pitch of .lambda./2 and forming a first IDT (inter-digital transducer), a plurality of second IDTs, substantially identical to one another and arranged with a predetermined pitch P for consecutively receiving a SAW propagated from the first IDT with respective propagation delays, and grounded dummy fingers in regions between adjacent IDTs. The first IDT is apodized in accordance with a Hermitian response to provide it with a pass band centered at a first frequency, and .lambda. is the wavelength of a SAW at a second frequency different from the first frequency and within the pass band. P is an integral multiple of .lambda./2, so that there is a constant finger periodicity throughout the SAW device whereby reflections between the second IDTs are avoided.

Abstract: At least one electro-acoustic transducer of a first surface acoustic wave device and acousto-electric transducers of a second surface acoustic wave device are arranged symmetrically to the first surface acoustic wave device about a line parallel to a propagating direction of surface acoustic wave and is phase-weighted differently from the remaining transducers having common phase-weighting, to improve an attenuation for stop frequency.

Abstract: The invention concerns electric/acoustic input transducers and acoustic/electric output transducers, in particular for a surface wave device, of the type comprising on a large face of a planar piezoelectric substrate: (i) two conductive input zones or output zones separated by a substrate band over which there extend respective parallel fingers which are interlaced according to a pattern chosen to form a row of fingers along this band, the general direction of the band being inclined to the direction of the fingers; and (ii) electric input means for applying high frequency signals between the zones so as to form sources of surface acoustic waves on the substrate or output means for extracting the signals detected by the device.

Abstract: A SAW transducer eliminates mechanical energy reflections by using one-quarter wavelength electrodes spaced at predetermined intervals. Dummy electrodes are shifted one-quarter wavelength to cancel energy reflections in the active electrodes. A pair of dummy electrodes is required for each active set of electrodes (the active set comprises one positive and two negative electrodes).

Abstract: A SAW (surface acoustic wave) device includes a substrate having thereon at least one apodized IDT (inter-digital transducer). The axis of the apodization pattern is inclined towards a driven conductive rail of the IDT at the ends of the pattern, whereby the driven end fingers have a low capacitive coupling to a ground plane on which the substrate is supported. The capacitive coupling to the ground plane may also be reduced by supporting the substrate on the ground plane via an insulating support, whereby an air gap or the insulating support decreases the capacitance between the IDT and the ground plane.

Abstract: A surface acoustic wave device is disclosed which performs frequency channelization in a relatively small volume. The invention utilizes a wide band incline step frequency transducer each step feeding an independent beam width compressor waveguide combination. The waveguides fan out with a wide radius of curvature to contain the wave in off pure mode axis propagation. The output of each waveguide then feeds an independent beam width expander and frequency selector interdigital transducer. The use of the waveguides as a tapping and narrow aperture transport mechanism minimizes defraction, allows the output transducers to be widely separated achieving isolation and permits a larger number of filters per substrate.

Abstract: A surface acoustic wave (SAW) device and a related method, for providing improved frequency response characteristics from a SAW spectrum analyzer or channelizer. The device includes a spectrum analyzer with a preprocessing SAW device configured to provide output signals with narrower passbands, lower sidelobe components, or both. The preprocessing SAW device is a tapped delay line in one embodiment, to simulate positional offsets in the placement of input transducers of the analyzer. The tapped delay line can also be used to provide amplitude weighting or can be configured in a chirp spacing, to transform the spectrum analyzer into a chirp analyzer. Another embodiment employs a thinned-electrode prefilter as the preprocessing device, to yield a frequency response with multiple narrow passbands, which are used to narrow the individual channel passbands of the spectrum analyzer or to suppress sidelobes in the frequency response.

Abstract: A surface acoustic wave device characterized in that in addition to linear first bus-bar electrodes which connect in alignment the edges of the same potential electrodes of interdigital electrodes, second bus-bar electrodes are provided which connect the same potential electrodes in the vicinity of the overlapping positions. Also disclosed is a surface acoustic wave device characterized in that the metalized ratio g/p, which is the ratio of the width of an electrode and the intercentral distance between the adjacent electrodes in an irregular pitch electrode group, is varied between 0.1 to 0.4 or between 0.6 to 0.9.

Abstract: A method for the correction of surface wave devices consists of measuring the transfer function of an entirely finished surface wave device and then designing a surface wave corrective filter, the transfer function of which enables the correction of the transfer function of the preceding device. The method makes it possible to correct, in particular, RAC type dispersive filters.

Abstract: A SAW slanted array correlator (SAC) comprises a piezoelectric substrate, an input and an output interdigital transducer deposited on the piezoelectric substrate, and a reflective array aligned with the transducers. The input and output transducer are slanted at equal and opposite appropriate angles to each other. The reflective array is disposed on the substrate at an angle the same as the angle of emplacement of the output transducer. The transducers comprise a number of interdigital electrodes with varying periodicity, the periodicity being the same for corresponding portions of the two transducers. The reflective array comprises a number of shorted interdigital electrodes having a periodicity corresponding to the periodicity of the output transducer. The reflective array comprises portion of selected electrodes which are active, partially active or inactive.

Abstract: In order to obtain greater flexibility in the design of a linear-phase electrical filter comprising an acoustic surface wave device including a pair of apodized transducers intercoupled by means of a multi-strip coupler, for example to obtain more equal contributions by the two transducers to the gain versus frequency characteristic of the filter, the transducers are apodized differently but have mutually complementary non-linear phase characteristics. First a transfer characteristic corresponding to the collective contribution to the desired overall gain versus frequency characteristic of the filter, is derived in terms of the z-transform and the roots or the reciprocals of the roots of the resulting polynomial in z.sup.-1 are found. These roots or reciprocals are then divided into two groups so that at least one pair of non-identical roots or reciprocals which have equal ratios between their real and imaginary parts and the product of the moduli of which is equal to unity are included one in each group.

Abstract: In a three-transducer surface acoustic wave device, an apodized electrode member is interposed between two interdigital electrode members, each having first and second ends and comprising interdigital electrodes between the first and the second ends either with a uniform density distribution or with a density distribution varied according to a prescribed rule of selective withdrawal of the interdigital electrodes. The apodized electrode member has first and second extremities and is given substantially minimum-phase and maximum-phase impulse responses for surface acoustic waves which are propagated either into or out of the apodized electrode member through one and the other of the extremities. Alternatively, an interdigital electrode member is interposed between two apodized electrode members. Each of the interdigital and the apodized electrode members is of the type described above. One of the apodized electrode member should have a substantially minimum-phase impulse response.

Abstract: A Surface Wave Acoustic (SAW) is constructed with hyperbolically curved electrode fingers. The transducers consist of relatively narrower inner electrode fingers and relatively wider outer electrode fingers, and 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 wave acoustic delay line is formed of a set of electrode assemblies disposed on the surface of a block of crystalline material propagative of a surface acoustic wave. In each of the assemblies, the electrodes are arranged in an interdigitated pattern. Reflected waves are cancelled by the construction of an additional electrode in each of an electrode assembly, the additional electrode extending only one-half the distance of the other electrodes and being spaced from an adjacent electrode by one-quarter wavelength. This introduces a 180.degree. phase shift between portions of relected waves which then cancel to remove the reflection. Also, in the case of closely spaced electrode assemblies, additional electrodes, equal in shape and size to the electrodes of the assemblies, are introduced between the assemblies in the form of a grid which propagates surface waves without reflection.

Abstract: The surface acoustic wave transducer in accordance with the present invention comprises a piezo-electric substrate, and a first type electrode-strips set which generates an electric reflection alone with no acoustic reflection and a second type electrode-strips set which generates both of an electric reflection and an acoustic reflection, both types being formed on the piezo-electric substrate. The first type electrode-strips set is formed by electrode strips with approximate width of 1/8 of the wavelength of the surface acoustic wave, while the second type electrode-strips set is formed by electrode strips with approximate width of 1/8 and approximate width of 3/8 of the wavelength of the surface acoustic wave.

Abstract: The invention provides a method of producing surface wave dispersive filters of RAC type, in which, in an RAC of known type, one of the input or output transducers is replaced by a transducer forming a surface wave filter and whose transfer function allows the errors of the initial transfer function of the RAC to be corrected.

Abstract: A SAW device includes aligned IDTs (inter-digital transducers) with a continuous pattern of fingers between their front edges. Each IDT may be symmetrical about its center, and includes front and back edge reflection suppressing regions of fingers of successively decreasing length, which serve to suppress surface acoustic wave reflections at the respective edges. Optional shield regions between the two front edge suppressing regions, and between the back edge suppressing regions and acoustic absorbers, include fingers of successively increasing length complementary to and adjacent the fingers of successively decreasing length of the reflection suppressing regions. The IDTs may be apodized or unapodized, and each IDT may include dummy fingers between its active region and each reflection suppressing region.

Abstract: In an acoustic surface wave multimode filter comprising a pair of acoustic surface wave resonators and a bus bar on a piezoelectric substrate with the bus bar shared by the resonators, the bus bar is rendered thicker than the resonators. Preferably, the bus bar should be about twice as thick as the resonators.