The design basis of the working frequency of the transducer involves the attenuation of ultrasonic energy by the sound transmission medium, the reflection characteristics of the detection target (such as defects) on the ultrasonic wave, the background noise of the sound transmission medium and the radiation impedance, etc.
There are many influencing factors that determine the working frequency of the transducer, such as the frequency of the excitation signal, the design of the assembly structure of the transducer, the application scope and restriction conditions of the working principle, and the physical properties of the material of the transducer itself. Many important properties of the transducer, such as directivity, transmitted sound power, receiving sensitivity, and sound field characteristics, are directly affected by its operating frequency. Therefore, various factors must be considered comprehensively when determining or selecting the operating frequency.
Generally speaking, the transmitting transducer can obtain the best working state when working at its resonance fundamental frequency, that is, it can obtain the maximum electro-acoustic conversion efficiency and transmit sound power. Similarly, under this condition, as a receiving transducer, the best frequency response and receiving sensitivity can be obtained.