| 摘要 |
A filter based on the use of surface acoustic waves comprises a coupling element (4) for transferring surface acoustic waves from one acoustic channel (3) to another acoustic channel (5) and for simultaneous forming the amplitude-frequency characteristic of the filter. The coupling element (4) contains two rows (21 and 24) of electrodes (22, 23 and 25, 26). Each of these rows (21, 24) is placed in the corresponding acoustic channel and has two groups of electrodes (22, 23 and 25, 26) which are parallel, respectively, to the electrodes (10, 11 and 16, 17) of the input (2) and output (6) converters of the pin type, which are mounted, respectively, in the first (3) and second (5) of these acoustic channels. The electrodes (23 and 26) of one group of each row (21 and 24) of the coupling element (4) are placed, respectively, between the electrodes (22 and 25) of another group of the same row (21 and 24) and constitute together with them, at least in one row (21), overlapping sections of variable length (12), whereas that row (21) of the electrodes (22, 23) corresponds to another row (9) of the electrodes (10, 11) with overlapping sections of permanent length (11), in the corresponding converter (2). The electrodes (22) of one group of one row (21) of the element (4) are galvanically connected with each other and with the electrodes (25) of one group of another row (24), whereas each electrode (23) of another group of one row (21) is galvanically connected directly with the corresponding electrode (26) of another group of another row (24). |
