The opening angle of an ultrasonic sensor
The working range is defined by the opening angle of the sound wave.
The opening angle is defined as the angle at which the ultrasonic energy measured at the center line of the sound beam has reduced to 50% or minus 3 dB.
Balluff ultrasonic sensors possess an opening angle of 8°. Objects located in this area are detected very well. The usable sensing distance will be reduced if objects are located outside of the opening angle.