Surface-Acoustic-Wave Device for Doppler Filtering of RADAR Burst Waveforms

A new type of reflective-grating matched filter has been developed for processing a Doppler-sensitive burst waveform consisting of 16 equally spaced phase-coherent linear-FM subpulses. The subpulses have 60-MHz bandwidth, are 3-mu s long, and have a period of 5 mu s. After addition of internal phase compensation, the phase response of the device over all 16 subpulses is within±20° of ideal. When a burst waveform is compressed in this burst matched filter, the range (time) sidelobes are approximately -40 dB down except for some near-in at -33 dB, and the Doppler (velocity) sidelobes are -32 dB down.