In the paper, which deals with the surface acoustic waves, is given the theory of synthesis of the asymmetrical delay line with the interdigital transducer with diluted electrodes. Based on derived theory, an experimentally verified delay line for use in the identification system, filters and resonators based on SAW for further specific applications has been designed.
Słowa kluczowe: delay line, diluted electrodes, surface acoustic wave, interdigital transducers, resonators.
W niniejszej publikacji dotyczącej powierzchniowych fal akustycznych znajduje się opracowana teoria syntezy nieproporcjonalnej linii opóźniającej z przetwornikiem międzypalcowym z rozcieńczonymi elektrodami. W oparciu o teorię pochodną opracowano i przetestowano eksperymentalnie specyficzne elementy akustoelektroniczne do różnych zastosowań.
Keywords: opóźnienia, rozcieńczone elektrody, powierzchniowa fala akustyczna, przetworniki międzypaliczkowe, rezonatory.
Among the perspective acoustoelectronic components with the surface acoustic waves (SAW) there are in addition to the bandpass filters also delay lines (DL) and resonators, which are used as selective elements of oscillators with harmonic oscillations. The main advantage is their small size and low weight, high mechanical strength, low sensitivity to vibration as well as the possibility to make the oscillators without the use of inductor. This is what guarantees their manufacturing perspective and wide range of use in measuring of electric and non-electric variables, in radio electronics, telecommunications, and introduces the necessity of elaboration of questions concerning to their theory and manufacturing. In the present paper it is elaborated the theory of an asymmetrical delay line with interdigital transducer (IDT) with diluted electrodes. Synthesis of Asymmetrical Delay Line An asymmetrical delay line has input IDT with a small number of electrodes (i.e. broadband), and output IDT with a large number of electrodes (i.e. narrowband). Module characteristic can be close to the synchronous frequency sufficiently accurately approximated by the function of sinx/x where x = N(f-f0)/f0 When increasing the number of electrodes IDT however, there is a strong signal caused by reflections from the edges of the electrodes, which substantially impairs the delay line properties and at the same time of the whole oscillator [1[. To suppress the signal we partly remove in the narrowband IDT the electrodes (i.e. "diluted" - divided into groups IDT). A similar problem arises in the synthesis of the filter with a narrow and very narrow pass band f3/f0 = 0,1 to 0,5 % (n. On the contrary, the methods of synthesis of filters with SAW are accurate at a relatively wide pass band f3/f0 = 1 to 30 %). Frequency and Time Characteristics of the Individual Groups of Electrodes in IDT with Diluted Electrodes The diluted IDT refers o [...]
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