Surface-acoustic-wave devices for communications

Surface-acoustic-wave (SAW) devices are used for bandpass filtering, matched filtering for radar pulse compression, or spread-spectrum signal processing, delay lines, and frequency control elements. The major advantages of the filters are their small size, high reliability, low cost, high Q, good reproducibility, temperature stability, wide dynamic range, and linear phase response. Major technological advances discussed include unidirectional SAW filters which eliminate bidirectionality loss and simultaneously suppress in-band spurious responses to achieve an insertion loss below 1 dB with a 0.04-dB peak-to-peak ripple. A novel surface-wave subsystem which offers revolutionary signal processing functions through transform processing is also described.