Here’s some helpful information about RF/Microwave and SAW filters:
The SAW Filter is a device using surface acoustic wave. A characteristic of the filer is that it can be made small, since Q is high and wavelength is about 5-10 fold of the electromagnetic wave, due to the use of mechanical vibration. Moreover, motion is limited to solid surface, and the filtering function is possible with only the circuit that can control SAW on the surface. Typical SAW filters include: RF SAW Filters, IF SAW Filters, SAW Duplexers, SAW Multiplexer and SAW Resonators.