Switchable Multichannel Surface Wave Devices.
Final technical rept. 15 Jan 73-1 Jul 74,
TEXAS INSTRUMENTS INC DALLAS
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The development of multichannel, frequency-selective filters for UHF application was effectively demonstrated. The demonstration unit provides more than 100 addressable bandpass channels covering the upper 100 MHz of the 225 to 400 MHz UHF communications band with only eleven filters and four distinct filterdesigns. This implementation of a large number of bandpass filter channels with variable center frequency andor variable bandwidth with relatively few transducers is made possible through acoustic surface wave technology and a unique engineering approach the selectable bandpass filter concept. The selectable concept combines two key principles a tapped surface wave transducer producing a periodic spectrum and electronic switching of the phases on the taps shifting that spectrum in discrete steps in frequency. By cascading several stages of these filters with different spectrum periods and bandwidths, a single channel of a much larger set of available passbands can be addressed by electronically altering the spectrum positions.
- Line, Surface and Bulk Acoustic Wave Devices