Reflective delay line using surface wave technique - has surface wave reflectors at different spacings from input-output transducers with associated impedances

摘要

The delay line has an interdigitated input/output transducer (10) and several surface wave reflectors (11) providing different propagation times of the surface waves, arranged at differing spacings from the input/output transducer (10). At least some of the surface wave reflectors (11) have associated impedances (12) of differing impedance value. The latter impedances (12) may be ohmic or capacitive, e.g. provided by a meandering resistance path applied to the substrate of the delay line. ADVANTAGE - Provides constant output amplitude.