Low-loss Floating Electrode Unidirectional Transducer for SAW Sensor

Abstract

Two types of interdigital transducer (IDT) structures of SAW devices have been investigated; one type consists in a classical single electrode transducer where the unit cell has two electrodes, and the other type has a design of floating electrode unidirectional transducer (FEUDT) where the unit cell has six electrodes per period. By taking the Fourier transform of the corresponding time response, the insertion loss (IL) of the SAW device with FEUDT is calculated as –2.6 (forward) and –20.5 dB (backward). At the same time, the device with conventional IDT exhibits an IL value of –8.4 (forward) and –7.8 dB (backward). It turns out that the design of a novel FEUDT type SAW device can efficiently reduce the insertion loss of the SAW device.