Using the system function to analyze the performance of transducer's impedance measurement method

From investigation of the advantages and disadvantages of conventional tri-voltage method,a method for the measurement of the transmitting transducer's impedance was presented to solve the difficult problem of examining the consistency of the transmitting phased array on the single-mode excitation sea spot.In the method based on the system function,the circuit structure of tri-voltage method was used but new parameters were measured.The principle of the method was given first.Then when resistors with different nominal values were used in the circuit the measured results for the impedance of transducers were reported.The results were compared with the higher precision impedance analyzer's.Finally,the error analysis was performed according to the impedance formula and the equivalent circuit's parameters were fitted.Under the condition of guaranteeing the sampling precision,by performance analyzing,the resistor value in series was chosen relatively smaller than the impedance of transducer,the measurement of impedance could achieve the same precision as the higher precision impedance analyzer's.Finally,the least square curve-fitting of measured curve indicated that the transducer's equivalent electrical parameters could be extracted accurately and used to design the matching network.