Also known as: SAW filter, surface acoustic wave filter

A SAW (surface acoustic wave) filter is a compact, sharp band-pass filter built on a piezoelectric substrate.¹ In an SDR front end it acts as a preselector — passing only the wanted band and strongly rejecting out-of-band signals that would otherwise overload the receiver.

A SAW filter passes one narrow band with steep skirts, protecting the receiver from strong out-of-band signals.

Overview

ADS-B receive chains commonly add a 1090 MHz SAW filter (often with a low-noise amplifier) so nearby cellular and broadcast transmitters don’t desensitise the front end.

Sources

1. Surface acoustic wave — Wikipedia, on the surface-acoustic-wave devices used to build compact sharp band-pass filters. ↩

See also

• Low-noise amplifier (LNA)
• ADS-B
• Bandwidth
• Attenuation

Learn it step by step

• Antennas 101