| 摘要 |
The invention relates to surface wave filters in double ring. It comprises reception transducers (304, 314) of such filter which are arranged on either side of the emission transducer (301) with respect to the emission axis of acoustic waves. Said waves are reflected to said transducers by means (302, 303) such as multiband reflectors or multiband couplers associated with reflectors (403-413). The invention allows to improve the symmetry of the two paths and to obtain an improved reduction of the triple transit echo.
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