| 摘要 |
PURPOSE:To prevent mutual interference by providing continuously a recessed groove with a square cross section to both ends of a piezoelectric substrate between surface acoustic wave elements on an electrode forming plane of the piezoelectric substrate. CONSTITUTION:The 1st surface acoustic wave element 21 is constituted by providing a comb type input electrode 23 fitted to the major plane of a piezoelectric substrate 22, shield electrode 24 linked with it, and comb type output electrode 25 provided opposingly to the electrode 24. Similarly, the 2nd surface acoustic wave element 31 is provided, and a sound absorbing member 26 is provided at both ends of both elements to absorb unnecessary reflected surface waves. The substrate 22 is bonded 27 with a stem 29 having leads 28 and connection 30 is made. Especially, a recessed groove 37 having square cross section l1 width and t1 depth is formed between both elements and it is made consecutive up to both ends of the substrate 22. Taking the width l1< element interval L, t1=nlambda where the wavelength of surface waves is lambda, and T=nt1 where T is the thickness of the substrate 22, the mutual interference between two surface acoustic elements can be prevented, and each element can be operated within respective bands. |
