Spectral Theory of Interdigital Transducers
and other papers
SAW devices - theory & experiment
Surface acoustic waves (SAW) devices are electronic components: filters,
resonators, and delay lines exploiting surface acoustic waves in piezoelectric crystals.
Interdigital transducer (IDT) converts electronic signal into SAW, which,
propagating 100000 times slower than electromagnetic waves, deliver signal delay in the device.
Signal filtering is performed by apodized IDT during electric to SAW signal conversion (or back
conversion by another IDT). This is transversal filtering (SAW signal is sampled by IDT fingers).
SAWs can be partially reflected by small perturbation of the crystal surface (shallow
grooves or thin metal strips, for instance). Effective SAW reflection
structures are systems of periodic grooves or strips. They are distributed reflectors applied
in SAW (Fabry-Perot) resonators. In another type of double channel resonators, reversing
multistrip couplers (MSC) are exploited to reflect SAWs with simultaneous
track-changing between two SAW channels.
The SAW technique is similar to microwave technique, with waveguides of thousands of SAW
wavelengths long. SAW devices are exploited in many electronic systems, home TV sets, cellular
phones, satellites, radars, etc.