Multiple Reflection and Multi-Echo Electroacoustic Bulkwave Delay Lines

The present paper describes new solutions to reduce the diffraction losses in the microwave bulkwave delay lines. By backfocusing the spreaded beam produced by the transducer, it is possible to concentrate the acoustic waves and increase the efficiency of the delay line. In this way, we have obtained at 2 GHz a 8 ¿s delay line with an attenuation less than 16 dB. By the same principle, reflection and focusing of an acoustic wave, it has been possible to build multiecho delay lines producing pulse trains with well-defined codes.