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1

Generalisation of transfer functions of inter-digital transducer and filter on basic of surface acoustic waves

Šimko M., Chupáč M.

Przegląd Elektrotechniczny

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2013

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R. 89, nr 11

229-232

EN

In the report we deal with the generalisation of transfer function which is derived from the three-gate model of the inter-digital transducer. Stated generalisation of transfer function includes the influence of adapter circuits attached to the transducer and allows its application for the description of any model´s functioning.

PL

Analiza przetwornik używany do zasilania i detekcji elementu SAW – z powierzchniową falą akustyczną. W modelu uwzględniono także układ adaptera.

2

Planar harmonic Green function for periodic elastic strips

Danicki E.

Journal of Technical Physics

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2007

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Vol. 48, no 2

95-109

EN

A system of periodic elastic strips (each one considered as a fragment of a plate) is characterized by a matrix relation between the Bloch series of displacements and stress at the bottom side of the system, which will remain in contact with the substrate supporting a propagating Rayleigh wave. The theory exploits the mechanical field representation in a spectral domain. It was found advantageous in formulation of the scattering problem for an elastic plate with stress-free cross-section, allowing us to apply ordinary boundary conditions instead of the variational ones. The result satisfies the energy conservation law with great accuracy, provided that sufficient number of complex modes are included in the solution. An algorithm is presented for modes evaluation; asymptotic properties of modes can be applied as well for higher modes. Perfect agreement of the proposed model with the experimentally verified perturbation model of thin strips is demonstrated.

3

Plane-wave theory of interdigital transducers comprising multi-strip periodic cells working in Bragg regime

Danicki E.

Journal of Technical Physics

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2005

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Vol. 46, no 4

219-234

EN

Interdigital transducers of surface acoustic waves are periodic or nearly periodic systems of strips. In several applications they work in the Bragg regime to obtain strong surface wave Bragg reflections. This paper presents generalization of the spectral, full-wave theory to the case of transducers exploiting periodic cells comprising many strips of arbitrary width and positions within the cell. A novel method is applied to solve the dynamic boundary-value problem by means of the generalized electrostatic analysis. The generalization is useful for two purposes: for analysis of transducers having substantially aperiodic strips (by applying large cell periods with respect to the transducer length), and for analysis, in the frame of spectral theory, of unidirectional transducers exploiting cells comprising several different strips and certain interconnections between them within each cell. The theory yields full characterization of such transducers, including the surface wave dispersion characterized by stopband frequencies, and the transducer directionality.

4

On electrostatics of finite planar system of strips applied in surface acoustic wave interdigital transducers

Tasinkevych V., Danicki E. J.

Journal of Technical Physics

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2005

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Vol. 46, no 3

175-193

EN

Planar systems of strips placed on a piezoelectric body are exploited in interdigital transducers for generation, detection and reflection of surface waves. The spatial field distribution in the plane of strips exhibits square-root singularities at the strips edges. In effect, the evaluation of charge spatial spectrum by direct application of the Fourier transformation to the spatial charge distribution never yields satisfactory accuracy. This is due to the strong dependence of the spectrum on the distribution details over the entire system. A new method is proposed here for direct evaluation of the spatial spectrum; the spatial distribution is obtained from it by the inverse Fourier transformation for certain auxiliary purposes and final verification of numerical results. The solution is constructed as a linear combination of the template functions, evaluated in spectral domain and satisfying the electric boundary conditions on the strips. The same functions are applied in the solution of the complementary problem of strips embedded in a preexisting electric field, assumed to be spatially variable (harmonic). In this case the strip total charge is evaluated dependent on the preexisting ("incident") field, as well as the Bloch harmonics of the "scattered" field in a wide spectral domain. Particular attention is dedicated to the numerical problems arising in evaluation of the template functions and the final charge spectrum. The computed examples show typical computational errors and how they were corrected by improving the numerical procedures.

5

Methods of IDT charge spatial spectrum evaluation

Tasinkevych Y.

Journal of Technical Physics

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2004

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Vol. 45, no 2

155-172

EN

Interdigital transducers (IDTs) have found numerous applications in electronic devices for excitation and detection of surface acoustic waves (SAWs). This paper discusses the methods of solution of the electrostatic problem arising in modelling of the IDT most important characteristic - its frequency response. Numerical results are presented based on the so-called spectral approach. Computation difficulties are discussed and their solutions are proposed.

6

Points of vanishing slowness curvature of quartz and lithium niobate

Danicki E.

Journal of Technical Physics

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2001

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Vol. 42, no 1

103-107

EN

There are paints on the slowness surface of anisotropic crystals which cannot be satisfactorily described with standard Gaussian curvatures. The paper presents complete sets of such points in quartz and lithium niobate, and also certain extraordinary points in Rochelle salt. The method of their evaluation and verification is presented briefly.