Title :
A piezoelectric double-mode filter using the complex-branch-type energy trapping
Author :
Watanabe, Hiroshi ; Nakamura, Kiyoshi ; Shimizu, Hiroshi
Author_Institution :
Fukushima Nat. Coll. of Technol., Iwaki, Japan
fDate :
5/1/1992 12:00:00 AM
Abstract :
A piezoelectric double-mode filter using the complex-branch-type energy trapping, that is caused by contributions from the complex branches of dispersion curves is proposed, and its theoretical and experimental results are presented for the width-extensional modes in a thin piezoelectric ceramic strip. Characteristics of the symmetric and antisymmetric trapped-energy modes in this filter have some interesting features different from those of the usual trapped-energy modes, such as noticeable undulations in the resonant frequency spectrum and sinusoidally oscillating decay of displacement in the unelectroded region. Based on these results, double-mode filters with a center frequency of about 1 MHz and a 3-dB fractional bandwidth of 3% are constructed. The filters of this type are useful in the medium frequency range below several megahertz because of the miniature size and the ease of supporting.<>
Keywords :
crystal filters; dispersion relations; piezoelectric oscillations; 1 MHz; antisymmetric trapped-energy modes; center frequency; complex-branch-type energy trapping; dispersion curves; fractional bandwidth; miniature size; piezoelectric double-mode filter; resonant frequency spectrum; sinusoidally oscillating displacement decay; symmetric trapped energy mode; thin piezoelectric ceramic strip; undulations; width-extensional modes; Bandwidth; Ceramics; Cutoff frequency; Electrodes; Filters; Piezoelectric materials; Power engineering and energy; Propagation constant; Resonant frequency; Strips;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
