Filter with narrow frequency pass-bond - uses resonators each comprising cylindrical tube vibrating longitudinally

摘要

The filter has an input and an output electromechanical transducer (31, 32) and a series of resonator tubes (1-3) between them, the latter having a common resonance frequency. The first and last resonator tubes (1, 3) are respectively coupled to the input and output transducers (31, 32) with coupling elements (41, 42) between each two adjacent intermediate resonator tubes, these elements vibrating in a direction perpendicular to the longitudinal vibration of the resonator tubes. The coupling elements (41, 42) are in the form of short cylindrical rods, with a much smaller diameter than that of the resonator tubes, and perpendicular to the latter, the end of each rod soldered to a respective resonator tube (1-3).