High Dispersive Acoustic Filter Study.
Interim progress rept. no. 1, 1 Oct 70-1 Mar 71,
HUGHES AIRCRAFT CO FULLERTON CA GROUND SYSTEMS GROUP
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The objective of this program is to develop a highly dispersive acoustic surface wave filter yielding a large compression ratio. This filter is designed to operate at a 300 MHz center frequency with a bandwidth of 100 MHz. By cascading three dispersive delay line modules with appropriate interconnecting networks and amplifiers it is planned to produce a deliverable chirp filter having a compression ratio of 30001. The report describes a new method for designing wideband chirp that effectively reduces the output amplitude and phase ripples in linear FM delay lines having appreciable fresnel integral terms in their frequency transform response. A detailed description of the analytical model which is used to study the characteristics of different delay line designs is also included. A new transducer geometry is described that significantly reduces the output amplitude and phase distortions in devices using weighted transducer structures. Finally, the preliminary results of the materials investigation are given together with a description of the fabrication techniques we are using to make high frequency dispersive delay lines. Author
- Line, Surface and Bulk Acoustic Wave Devices