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具有两个相同换能器(具有固定的叉指间隙)的瑞利波延迟线的相对带宽等于一个换能器指对数倒数的0.63倍。为了获得50千赫的带宽,在100兆赫下每个换能器的指数约为2500。要克服制作这种换能器的工艺问题是困难的。声阻抗随金属叉指周期性变化,从而改变了在换能器下面行进的波的传播特性。
The relative bandwidth of a Rayleigh delay line with two identical transducers (with a fixed interdigital gap) is equal to 0.63 times the reciprocal of the logarithm of one transducer. In order to obtain 50 kHz bandwidth, the index of each transducer is about 2500 at 100 MHz. It is difficult to overcome the process problems of making such transducers. The acoustic impedance changes periodically with the metal fingers, changing the propagation characteristics of the waves traveling under the transducer.