| 摘要 |
PROBLEM TO BE SOLVED: To provide a structure setting the suppression ratio of an auto correlation waveform outputted from a second encoding electrode part to be almost equal to the suppression ratio of the auto correlation waveform outputted from a first encoding electrode part in a surface acoustic wave element for delay detection, which has the first and second encoding electrode parts. SOLUTION: In a surface acoustic wave element for delay detection, which is used for an SS(spread spectrum) communication system, an input IDT part 3 and the first and second encoding electrode parts 4 and 5 are formed on a piezoelectric substrate 2. An interval between the first encoding electrode part 3 and the second encoding electrode part 4 is set to length with which a auto correlation peak obtained from the encoding electrode parts is shifted by one period of a spread spectrum code. The center frequency of a transmission characteristic, which is obtained in the input IDT part 3 and the first encoding electrode part 4, is almost matched with the center frequency of the transmission characteristic, which is obtained in the input IDT part 3 and the second encoding electrode part 5. |
