SU506114A1 - Electromechanical filter - Google Patents

Description

one

The invention relates to radio engineering.

A known electromechanical filter comprising an input and output transducer, an oscillatory system in the form of a set of disk resonators with nodal circles of the disks.

For technological reasons, with the external arrangement of the communication wires, the diameter and thickness of all the disks of the oscillating system must be the same. The latter, in the well-known filter, is achieved by using truncated disks as resonators used in the oscillation mode with nodal diameters. This, in turn, complicates both the fabrication of resonators and the assembly and welding of an oscillatory system. In addition, when used in an oscillatory system, disks in oscillation mode with nodal diameters have to be confronted with the effect of frequency bifurcation and the appearance of sidebands.

The purpose of the invention is to reduce the passband of the filters while maintaining high mechanical strength.

Into the proposed filter between disk resonators, additional communication elements are inserted, fixed in places located on the nodal circles of disk resonators.

FIG. 1 shows schematically an oscillatory filter system; in fig. 2 - two-resonator node of the oscillating system; in fig. 3 - two-resonator node, but without a communication element operating in the mode of longitudinal oscillations; in fig. 4 is a two-resonator node, but without a communication element operating in bending mode.

The electromechanical filter contains a resonator 1, an input transducer 2, an output transducer 3, coupling elements 4 operating in longitudinal mode, coupling elements 5 operating in bending mode.

There are no complex communication circuits in the oscillatory system, and all the resonators oscillate in one stable oscillation mode.

We illustrate the effect obtained in the design using the example of two-unit units (Fig. 2-4). Here, disk cavities 1 are oscillated in oscillation mode with one nodal circle, and elements

Links 4, 5 operate respectively in the modes of longitudinal and bending vibrations. If in the oscillating ms disk to fix the instantaneous position shown in FIG. 3, 4 by a dotted line, then taking into account the directions of speeds shown on these drawings at the points of attachment of the communication elements 4, 5, the resonators will be in antiphase. If we now return to the node (Fig. 2), where the processes occurring at the nodes (Figs. 3, 4) are combined jTo it is easy to see that for one of the communication elements, depending on the prevalence of the communication coefficient, anti-inclusion condition.

A similar consideration confirms the fulfillment of the conditions of antiphase inclusion for any kind of axisymmetric oscillations in disk resonators 1.

It should be noted that the reasoning was carried out on the simplest nodes containing only one communication element 4, 5 in

mode of a particular type of oscillation. In practice, other quantitative combinations of communication elements may be used. In addition, in the proposed filter, it is possible to use communication elements that operate not only in purely longitudinal and purely bending vibration modes, but also in an offset mode, when the coupling between the resonators is clearly dominated by one of the vibration types of the corresponding communication element.

F o

rmula of invention

Electromechanically filter containing input and output transducers, an oscillating system in the form of a set of disk resonators with nodal circles connected by communication elements fixed in an antinode of oscillations between the nodal circles of disks, characterized in that in order to narrow the passband while maintaining high mechanical strength, between the resonators, additional communication elements were inserted, fixed in places, located on the nodal circles of the resonators.

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