SPATIAL HARMONIC TRANSDUCERS FOR SURFACE WAVE DEVICES

摘要

A spatial harmonic transducer of a SAW device is made directional for SAWs at a spatial harmonic signal frequency of the transducer by a reflector for reflecting SAWs at that frequency. The transducer comprises repeated groups of consecutive electrodes having a predetermined polarity sequence, positioned to operate coherently for SAWs at the signal frequency. The reflector comprises reflector electrodes for producing constructive and destructive interference in opposite SAW directions, with electrode widths and spacings of at least a quarter wavelength at the signal frequency. A SAW device with two such spatial harmonic SPUDTs using different polarity sequences can provide desirable characteristics for filters and delay lines at frequencies of about 2GHz.