Converter is an energy conversion device, need many parameters for its performance description and evaluate.
Converter characteristic parameters including: resonant frequency, frequency bandwidth, electromechanical coupling factor, electroacoustic efficiency, mechanical quality factor, impedance characteristic, frequency characteristic, directivity, launch and receive sensitivity and so on.
Different purpose converter requires different performance parameters. For example, launch type ultrasonic converter, requires powerful output power and high energy conversion efficiency; but for receive type ultrasonic converter it needs wider frequency band and high sensitivity and distinguishability etc.
With the above reason, in the processing of detailed design, must design every parameter according to specific application.