The principle of Fourier transformation by wave diffraction has been demonstrated using surface acoustic waves. The RF signal to be analyzed drives a phased array of SAW interdigital transducers that acts like a curved diffraction grating to focus and angularly disperse the generated acoustic waves with frequency. An array of output transducers partitions the dispersed signal spectrum into contiguous narrow bands. The approach is novel and has a number of significant features. The device is passive, linear, and bidirectional, and preserves phase information. Sidelobes and spurious signals can be suppressed by amplitude weighting the input transducer elements and using mode selective output transducers. Several experimental devices have been constructed on LiNbO3. These were evaluated electrically and with a scanning laser probe.
R. E. Brooks,
"Saw RF Spectrum Analyzer/Channelizer Using Acoustic Wave Diffraction", Proc. SPIE 0639, Optical Information Processing II, (24 September 1986); doi: 10.1117/12.964337; https://doi.org/10.1117/12.964337