The Design and Applications of Highly Dispersive Acoustic Surface-Wave Filters

The development of a low-loss broad-band linear FM dispersive filter having a time-bandwidth (TB) product of 1000 is discussed. Two systems applications for highly dispersive linear FM filters--pulse compression RADAR and a microscan receiver--are discussed with emphasis on filter performance requirements. The principal factors which influence the design of surface-wave filters are reviewed and theoretical design procedures are outlined. The 1000:1 filters, which are implemented on strong-coupling YZ lithium niobate, typically meet the design goal of a 100-MHZ rectangular passband and have a CW insertion loss of less than 35 dB. Measured data are presented for the filter performance in a pulse-compression loop and in a prototype broad-band microscan (compressive) receiver.