I.G. Antsev, S.V. Bogoslovsky, G.A. Sapozhnikov, A.N. Trofimov
Effective reduction of compressed signal amplitude is provided when the phase of topology adjacent areas changes to 180 degrees. Physically this phase change for all areas can be achieved only by the local changes of primary signal delay time with one side of the interdigital transducer (IDT). A significant signal change at the sensor output may also be achieved under other laws of speed change of a surface acoustic wave (SAW) on the acoustic waveguide. In particular there can be used constructions in which the linear dependence of SAW velocity (Roberval parallelogram) is implemented.
The main idea of the proposed method is to provide the noise filtering not only by reader but also by sensor, i.e. sensor and receiver successively realize (at first – the sensor, then –the receiver) optimal input signal filtering (for the sensor it is the one signal type, for the receiver – the other). The difference in signals structure of sensor and receiver input clearly appears in signal duration. The signal of the receiver input will have twice duration than the signal of the sensor input. As in filtering by reader, filtering by sensor allows to improve signal/noise ratio. Moreover, such approach allows to conserve energy of retransmitted signal that results in additional effect – improvement of the whole measuring system range.
The proposed approach is the basis for creating the whole class of new sensors, which could be called mirror topology sensors. The proposed construction is a special case of using a common physical effect of dynamic inhomogeneities decompression on mirror topology. The surface, bulk acoustic and also magnetostatic waves above all should be referred to dynamic inhomogeneities of practical interest.