SLASEC8B February 2017 – January 2019 PGA460-Q1
The strength of ultrasonic waves propagated into the air attenuate proportionally with distance. This attenuation is caused by diffusion, diffraction, and absorption loss as the ultrasonic energy transmits through the medium of air. As shown in Figure 137, the higher the frequency of the ultrasonic wave, the larger the attenuation rate and the shorter the distance the wave reaches.
|t = 20 °C|
An ultrasonic transducer has a fixed resonant center frequency with a typical tolerance of ±2%. The lower frequency range of 30 to 80 kHz is the default operating range for common automotive and consumer applications for a step resolution of 1 cm and typical range of 30 cm to 5m. The upper frequency range of 180 to 480 kHz is reserved for high-precision industrial applications with a step resolution of 1 mm and a typical range of 5 cm to 1 m.