Browsing by Author "Chang, W. S."

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Manipulation of extraordinary acoustic transmission using cascaded both-sides-open disk resonator array
(2020-08-01)
Lee, Y. L.
;
Wei, K. H.
;
Tsai, Y. P.
;
Chang, M. S.
;
Chiang, C. T.
Extraordinary acoustic transmission (EAT) through cascaded both-sides-open disk resonators (BSODRs) in a square lattice array (SLA) is investigated. A single BSODR consists of one disk cavity that is sandwiched by two tubes. These structures are realized by stacking perforated steel plates and immersing them in water. EAT is studied through single-layer, two-layer, three-layer, and four-layer BSODRs in SLAs. The EAT orders increase with increasing numbers of cascading layers. The quality factors of the highest order EAT peaks also increase with increasing numbers of cascading layers. The EAT characteristics of each structure can be predicted using a spring-mass model. A coupled spring-mass model with two oscillators is proposed. The vibration of the steel part is considered one oscillator and that of the water part of the BSODR represents the other oscillator. The model verifies that the EAT resonances are excited by coupling of the vibration from the steel plates to the water part. The experimental transmission spectra agree with the numerically simulated spectra. The EAT frequency is sensitive to the longitudinal sound velocity. Because of the increased quality factor, the figure of merit is enhanced eight times by cascading four BSODR layers. The proposed structure is suitable for acoustic filter and sensor applications.
Uniplanar microstrip periodic structure for microwave circuits
(2011-04-14)
Chang, W. S.
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Chang, C. Y.
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電信工程研究所
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Institute of Communications Engineering
A novel microstrip slow-wave structure is presented. The slow-wave factor is mainly controlled by the signal strip and the inserted ground metal pattern in a coplanar manner. A third-order Chebyshev filter was designed and fabricated to demonstrate the proposed structure. Good agreement between the simulated and measured responses is observed.
Wideband high-isolation and perfect-balance microstrip rat-race coupler
(2012-03-29)
Chang, W. S.
;
Liang, C. H.
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Chang, C. Y.
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電信工程研究所
;
Institute of Communications Engineering
A microstrip rat-race coupler with high isolation and perfect balance is presented. By modifying March's rat-race coupler with two additional short-circuited stubs, the isolation and the amplitude/phase balance of the proposed coupler improve significantly. The circuit can be easily fabricated on a single-layer substrate using the conventional printed circuit board process.