| 摘要 |
PROBLEM TO BE SOLVED: To improve a temperature characteristic and to realize a stable operation against a temperature change by setting a frequency making interdigital electrode specification radiation conductance be maximum to be larger than a frequency where a reflection coefficient that an interdigital electrode has shows a maximum value. SOLUTION: A frequency in the peaks of radiation conductance in first IDT 12, second IDT 13 and third IDT 14 is set to become almost similar to the maximum frequency of the stop band of a reflector 15. When the pitches PT and PR of respective IDT 12, 13 and 14 and the reflector 15 become large, the frequency becomes small and the frequency becomes large when pitches PT and PR become small. Thus, respective IDT 12, 13 and 14 are formed so that the pitches PT of first IDT 12-third IDT 14 and the pitch PR of the reflector 15 become small. The peak of radiation conductance is formed in an area on the outer side of the stop band.
|
