Isolation of SAW-transducer response using 3-port measurements

A refined method for determining the magnitude and phase of the transconduction of a surface acoustic wave (SAW) transducer is presented. A three-transducer configuration of the SAW-device is assumed. Three sets of two-port S-parameters are combined to isolate the desired transducer. All three transducers can be different, which is convenient in practice. A continuity criterion in the complex plane solves the phase ambiguity of the transduction. A second set of two-port S-parameters, measured by placing an absorber between the transducers, allows the extraction of the pure SAW response. This is especially useful, since gating in the time or frequency domain cannot remove passband spurious responses. The theory is illustrated by an example of a SAW-device with a long apodized transducer. The transmission of this device provides nulls in the passband as well as fast and steep phase changes due to the apodization based on a shaped BPSK-modulated waveform. Measured and predicted values of an extended impulse model, concerning only SAW effects, are compared. Precise effective tap excitation for iterative correction in a second mask is extracted