| 摘要 |
PURPOSE:To enhance the resolving power of a sensor, by providing a heat generator on a piezoelectric substrate in a state folded back to the direction oblique to the propagation direction of a surface acoustic wave (SAW) and reducing the ripple and group delay strain in the pass-band of a SAW delay wire. CONSTITUTION:A transmitting cross digital type electrode 2 for emitting SAW and a receiving interdigital type electrode 3 for receiving SAW are provided to the surface of a piezoelectric substrate 1 and a heat generator 4 is provided so as to be folded back to the direction oblique to the propagation direction of SAW and SAW emitted from the transmitting electrode 2 is the same phase and prevented from reflecting from the transmitting electrode 2. An amplifier 5 is provided between the signal input side electrode of the transmitting electrode 2 and the signal output side electrode of the receiving electrode 3 to constitutes a SAW transmission circuit and connected to a frequency counter 6. Because ripple and group delay strain are not generated in the pass-band of SAW, the resolving power, reliability and stability of a sensor can be enhanced.
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