Bandwidth, power and noise considerations in airborne cMUTs

Capacitive micromachined ultrasonic transducers (cMUTs) offer wider bandwidth in air due to their low mechanical impedances. The impedance mismatch between the air and transducer decreases with the smaller device dimensions increasing the bandwidth at the expense of the degradation in the transmit power and the receive sensitivity. In this work, the bandwidth of cMUT is optimized by increasing its radiation resistance. This is done by properly choosing the size of cMUT membranes and their placement within an array. This selection not only brings an improvement in the transmitted power when it is used as a transmitter, but also improves the noise figure when it is used as a receiver. A further improvement in the noise figure is possible when the cells are clustered and connected to separate receivers.