The overall transmission coefficient αT,G between a transmitter of characteristic impedance R1 and a gas of impedance R2 separated by a matching layer of impedance R is given by eqn [16.40]. By differentiating [16.40] and setting the derivative equal to zero (or any other method), show that αT,G is a maximum when Professional Australia Essay Writers |

(a) Explain briefly the meaning of the following terms used in ultrasonics:

(i) Attenuation

(ii) Matching layer

(iii) Resonant stationary wave.

(b) An ultrasonic transmitter is in the form of a piezoelectric disc of diameter 1.0 cm and thickness 2.0 mm. The transmitter is to be used to launch 1 MHz pulses into biological tissue. Use the concepts of part

(a) and the data below to detail what modifications are made to the transmitter so it meets the following specification:

(i) Maximum power for pulse transmission from the front face into the tissue

(ii) Minimum power for pulse transmission from the rear face into the tissue.

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