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延迟线是基本的声表面波器件之一,在雷达、通讯、电子对抗、声纳和电视等方面有很广泛的应用.在声表面波延迟线中,一般把延迟时间在1微秒以内的延迟线称为短延迟线.有的延迟时间甚至低至0.1微秒.延迟时间愈短,必然是输入叉指换能器和输出叉指换能器靠得愈近.我们以中心频率20的赫延时0.488微秒的延迟线来说明.假定输入和输出换能器都是4对指的话,那么换能器的空间周期λ与两换能器的内边缘距1′之比约是1/5.5.可见两个换能器是靠得近的(图1).这就是短延迟线结构上的特点.
Delay line is one of the basic surface acoustic wave devices, and has wide applications in radar, communications, electronic warfare, sonar and television etc. In SAW delay line, the delay time is generally within 1 microsecond The delay line is called the short delay line, and some delay times are as low as 0.1 microseconds. The shorter the delay time is, the closer the input and output interdigital transducers are to our input. Hertz 0.488 microsecond delay line to illustrate the assumption that the input and output transducers are four pairs of fingers, then the transducer space period λ and the inner edge of the two transducers 1 ’ratio of about 1 /5.5. It can be seen that the two transducers are in close proximity (Figure 1). This is a structural feature of the short delay line.