Spatial distribution of echo-signal amplitudes as a function of defect coordinates is computed for ultrasonic transducer with arbitrary shape and for pulse signals of different duration. Such a distribution contains useful information for designing of automatic ultrasonic NDT devices. For radiation mode the transducer is approximated by external normal tensions which are applied to the surface of an elastic half-space. Transducer integrates normal surface displacements for reception mode. At first, the frequency gain of the "radiation-reflection-reception" process is computed for a specific position of a defect. Then frequency synthesis algorithm is applied and maximal absolute value of the obtained echo-signal is computed. Distribution of this amplitude for various positions of a defect at arbitrary plane section (vertical or horizontal one) gives visual picture of an echo-signal field. Computation of signal spectrum specific frequency is based on two different algorithms. One of them (spatial-spectral algorithm) employs 2D FFT and is applied for small distances within near-field zone. Another algorithm employs spatial convolution procedure and is meant for bigger distances within both near and far field zones. The echo field structure for transducers with rectangular aperture of the same area and different ratio of sides are computed and discussed. The focusing rectangular transducer echo-field is computed.
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