| 摘要 |
A surface acoustic wave component contains two fan-shaped interdigital transducers disposed on a piezoelectric substrate, the prongs and gaps of which transducers forming groups having the same length, called cells, between them, and narrow in the averaged prong direction. The cells are structured like cells of unidirectional transducers, and at least one of the fan-shaped interdigital transducers is composed of partial transducers. The partial transducers are disposed one behind the other, perpendicular to the averaged prong direction. |
| 主权项 |
1. A surface acoustic wave component comprising:
two fan-shaped interdigital transducers disposed on a piezoelectric substrate, said transducers having prongs and gaps that lie between the prongs forming groups having the same length, and narrow in an averaged prong direction, said groups being structured as cells of unidirectional transducers, wherein at least one of the fan-shaped interdigital transducers is composed of partial transducers, wherein: a) the partial transducers are disposed one behind the other, perpendicular to the averaged prong direction, ba) at least one of the narrowing gaps between two cells of at least one of the fan-shaped interdigital transducers is widened by an additional width Z that narrows in the same manner, of (g+m/h) times the length of a cell that narrows in the same manner, or bb) the narrowing gap of at least one of the fan-shaped interdigital transducers, which is widened by an additional width Z that narrows in the same manner, is selected to be such that the conditions |sin(π·h1·Z/p|<|sin(π·Z/p| and |sin(π·h2·Z/p|<|sin(π·Z/p| are fulfilled, whereby p is the length of a cell that narrows in the same manner as the prongs and the gaps, and Z and p, as a result of the narrowing, are reduced by the same factor in comparison with maximal dimensions, so that the ratio Z/p is independent of the location in the averaged prong direction, and whereby h1 and h2 are the orders of two harmonics to be suppressed at the same time, and that c) the cells on a left or on a right of a widened gap belong to different partial transducers, and the cell on the right of a widened gap has an opposite electrical polarity in comparison with the cell disposed on the left of the widened gap,wherein g is a natural number or zero, h is a prime number of the prime factor breakdown of the order of the harmonic to be suppressed, and m is selected as a whole number that lies in the range of 1≦m≦h−1. |
