An Efficient Method of Forming a Long Chirp with Small Phase Distortions

摘要

Forming a long chirp with small phase distortions is investigated experimentally using a series connection of surface-acoustic-wave (SAW) disperse delay lines (DDLs) implemented on YZ-cut LiNbO_3 substrates. Relationships obtained for the frequency responses of DDLs with the ladder topology are based 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 re presented for 150μs and 300μ s pulses when the bandwidth-duration product is 6000 and 12000, respectively. For these two pulses, the level of sidelobes in the compressed signal is from -25 to -30 dB and from -22 to -30 dB, respectively. Theoretical and experimental investigations have revealed a number of specific properties of the frequency responses of SAW DDLs.