Electroacoustic Transducer Aperture Weighting for Mode Suppression
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Solution Overview
Problem
Existing electroacoustic transducers in RF filters often suffer from deteriorated electrical properties due to the presence of unwanted wave modes, which conventional methods struggle to suppress effectively, leading to reduced efficiency.
Innovation Solution
The use of a transducer design with a periodic dielectric material in the acoustically active region, featuring a transversal velocity profile with alternating minimal and maximal values, flanked by edge structures, to selectively suppress unwanted transversal modes and enhance the piston mode, thereby improving the electrical properties of RF filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transducer designs are used, then the device complexity is low, but unwanted transversal modes are not suppressed effectively, deteriorating the electrical properties of RF filters
Solution Approach 1:
The patent applies aperture weighting by varying the width of interdigitated electrode fingers across the transducer aperture. The electrode fingers have different widths in different regions, creating a non-uniform excitation profile that suppresses unwanted transversal modes while maintaining the fundamental mode. This local variation in electrode geometry achieves mode suppression without adding separate suppression components.
Solution Approach 2:
The transducer aperture is divided into multiple regions with different electrode finger widths. By segmenting the electrode structure into zones with varying dimensions, the patent creates a distributed aperture weighting function that shapes the excitation profile to suppress specific transversal modes while passing the fundamental mode.
2Reliability
If aperture weighting is used to suppress unwanted transversal modes, then the electrical properties improve, but the transducer requires non-uniform electrode structures increasing manufacturing complexity
Solution Approach 1:
The patent implements aperture weighting through local variation of electrode finger widths. Each region of the transducer has specifically designed electrode dimensions tailored to achieve the desired excitation profile. This approach integrates the suppression function directly into the electrode geometry rather than requiring separate manufacturing steps or components.
3Reliability
If piston mode transducers are used to suppress unwanted transversal modes, then mode suppression is achieved, but the device complexity increases compared to conventional designs
Solution Approach 1:
The patent achieves piston-like mode suppression through local variation of electrode finger widths across the aperture. By creating regions with different electrode dimensions, the excitation profile is shaped to suppress transversal modes while maintaining the fundamental mode, eliminating the need for separate piston mode components or complex additional structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively suppresses unwanted transversal modes and enhances the fundamental mode, resulting in improved electrical properties and efficiency of RF filters by optimizing the wave guiding properties.
Implementation Method 1
Utilizing the piezoelectric effect the transducer converts an electromagnetic RF signal into acoustic waves and vice versa
Implementation Method 2
The transducer further comprises a transversal velocity profile of acoustic waves propagating in the transducer
Data Source
AI summary
An improved electroacoustic transducer with an improved mode profile is provided. The transducer comprises a transversal velocity profile with a periodic structure and an edge structure flanking the periodic structure. The velocity profile also allows to suppress the SH wave mode. A dielectric material with a periodic structure contributes to the formation of the periodic structure of the velocity profile.