Arbitrarily oriented SAW gratings: network model and the coupling-of-modes description
E L Adler1, M P da Cunha, O Schwelb
1Dept. of Electr. Eng., McGill Univ., Montreal, Que.
Summary
A new network model accurately describes surface acoustic wave (SAW) devices with nonsymmetric orientations. This model validates the coupling of modes (COM) description and offers simple formulas for COM coefficients across wide bandwidths.
Area of Science:
- Electrical Engineering
- Materials Science
- Acoustics
Background:
- Surface Acoustic Wave (SAW) devices are crucial for signal processing.
- Existing models often struggle with nonsymmetric orientations and arbitrary crystallographic cuts.
- Accurate modeling is essential for optimizing SAW device performance.
Purpose of the Study:
- To develop a comprehensive network model for SAW structures with arbitrary orientations.
- To evaluate the phenomenological coupling of modes (COM) description using the new model.
- To derive simplified, explicit formulas for COM coefficients.
Main Methods:
- A unit-cell-based network model incorporating transmission lines and a novel reactive element for asymmetry.
- Perturbation formulas to calculate the additional reactive element.
- Comparison of model predictions with analytical COM formulas and numerical calculations.
Main Results:
- The network model accurately accounts for energy storage and asymmetry in SAW structures.
- The incremental COM description can be derived from the network model.
- New, simple explicit formulas for COM coefficients were derived, showing good accuracy over a 30% relative bandwidth.
Conclusions:
- The proposed network model provides a robust framework for analyzing SAW devices with complex orientations.
- The derived formulas offer a computationally efficient way to predict COM coefficients.
- This work advances the design and understanding of high-performance SAW gratings.
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