The Study of Cable Effect on High-Frequency Ultrasound Transducer Performance

Transmission cable has great influence upon the performance of the high-frequency ultrasound transducers, especially for those intrusive applications, where front-end tuning circuits are unavailable. In this paper, a method of modeling high-frequency ultrasound transducers by considering the cable effect was proposed based on the transmission line theory. A full examination of various cables effects were achieved through the proposed model. Typical transducer characteristics, including the output impedance and pulse-echo response are attained and good agreement with the experimental results of 12, 20, and 50 MHz transducers are found both in time and frequency domains. The cable was found to be able to greatly change both the resonance impedances and phases. Specifically for the 20 MHz transducer, a 2.2-m cable could cause an increase of the parallel resonance impedance and phase from 11.07 to 57.94 Omega and -35.15 degrees to 14.31 degrees, respectively, leading to a less efficient coupling and lower pulse-echo intensity while wider bandwidth. In addition, the increase of the cable length can further decrease the pulse-echo intensity but rarely alter the frequency response.