| 摘要 |
An acoustic surface wave device uses an in-line arrangement of two apodized interdigital electrode arrays 2, 3 to launch and receive surface waves to overcome problems of short overlap sources and of diffraction by making the arrays approximately 3 lambda c wide between the outer boundaries of the bus bars so that the arrays can each only propagate and transduce a single acoustic surface waveguide mode which is symmetrical about the axis of the array. Because the acoustic surface wave energy is propagated in a guided mode, energy launched by pairs of electrodes with a short overlap rapidly spreads to fill the entire transducer aperture and a similar situation in reverse applies at the receiver.
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