An efficient method of forming a long chirp with small phase distortions

Forming a long chirp with small phase distortions is investigated experimen tally using a series connection of surface-acoustic-wave (SAW) dispersive d elay lines (DDLs) implemented on YZ-cut LiNbO3 substrates. Relationships ob tained for the frequency responses of DDLs with the ladder topology are bas ed on the model of the superposition of partial reflected waves. A chirp is formed and compressed at the center frequency of 150 MHz in the frequency band of 40 MHz. The experimental results are presented for 150-mu s and 300 -mu s pulses when the bandwidth-duration product is 6000 and 12000, respect ively. For these two pulses, the level of sidelobes in the compressed signa l is from -25 to -30 dB and from -22 to -30 dB, respectively. Theoretical a nd experimental investigations have revealed a number of specific propertie s of the frequency responses of SAW DDLs.