| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize a device and to obtain superior frequency stability by arranging a horizontal elastic coupling type reflector, which has the function of transmitting surface acoustic wave on a first-class propagation path onto a second-class propagation path via a horizontal elastic coupling phenomenon and reflects it, in an adjacent relation to a waveguide, which propagates the surface acoustic wave which a transmission side interdigital electrode generates. SOLUTION: An input voltage of a signal source 118 is applied to an IDTI (transmission) 105, and a surface acoustic wave thus excited is propagated to an X-axis 119 direction orthogonal to electrode fingers 112, 115, 114 or the like and is made incident to a wave guide 101. After this, the surface acoustic wave is transmitted to reflectors 1 102 and 2 103 by using a horizontal elastic coupling phenomenon, is further reflected in the -X direction and is propagated to an IDT 2 (reception 1) 105 and an IDT 3 (reception 2) 107. The propagated surface acoustic wave is received by these IDT and becomes an electrical signal among terminal impedance terminals ZL 117. Thus, the total length of an element can be shortened by about 30%, and an satisfactory small-sized SAW filter can be obtained.
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