Characteristics of directivity factors of ultrasonic transducer
Under normal circumstances, the ultrasonic transducer used is required to have sharp directivity, just like the use of a condensing flashlight for illumination, which is conducive to concentrating the emission of energy, obtaining a higher signal-to-noise ratio during reception, and also conducive to detection Target positioning evaluation. The directivity of an ultrasonic transducer is related to its radiation surface size, structure, working frequency, and characteristics of the sound-transmitting medium. Usually, directivity factors can be used to reflect the directivity of the ultrasonic transducer:
For the transmitting ultrasonic transducer, the so-called directivity factor refers to the mean square sound pressure of a certain frequency at a certain point far away from the transmitting ultrasonic transducer on the main axis sound pressure of the transmitting sound beam and passing through the point and the transducer The ratio of the mean square sound pressure of the same frequency at a point on a concentric sphere. For the receiving ultrasonic transducer, it refers to the ratio of the square value of the electromotive force generated by the sound wave of a certain frequency along the main axis of the transducer to the square value of the electromotive force generated by the diffuse sound field with the same frequency and the same root mean square sound pressure.
The directivity factor of an ultrasonic transducer can also be expressed in decibels (dB), which is called the directivity index, which is equal to the common logarithm of the directivity factor multiplied by 10. For the transmitting transducer, the directivity index can also be called the directivity gain.