SU426303A1 - VIBRATIONAL SYSTEM FOR ELECTROMECHANICAL FILTER - Google Patents

Description

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The invention relates to radio filters and can be used in various types of radio equipment in the frequency range 10-500 kHz.

A known oscillating system for an electromechanical filter, comprising series-arranged resonators connected by bridges.

The implementation of an electromechanical filter using a known oscillatory system is associated with the difficulty of obtaining a monotonically increasing amplitude-frequency characteristic in the region of the retention band because of the dips in it, which are characterized by the presence of parasitic oscillations arising in the oscillatory system.

The aim of the invention is to improve the monofrequency of the filter.

This is achieved by the fact that the proposed oscillatory system is made of a set of at least three types of different resonators, for example a cylinder, a dumbbell and a two-section dumbbell.

FIG. 1-5 shows the variants of the proposed oscillatory system for an electromechanical filter (EMF).

The oscillatory system for EMF (Fig. 1) contains Consistently located resonators 1, connected by links 2, and these resonators are made from a set of

at least three different types: cylinder 3, dumbbell 4 and two-piece dumbbell 5 (fig. 2), or cylinder 3, dumbbell 4 and the rolling pin resonator 6 (fig. 3), or cylinder 3, dumbbell 4 and resonator 7 with smoothly varying the length by wave parameters (Fig. 4), or cylinder 3, dumbbell 4 and resonator 8 with wave parameters drastically changing from length (Fig. 5). The mutual arrangement of the resonators may be different and, as can be seen from the drawings, the resonators have different wave parameters, i.e., they differ in either the wave length or the characteristic impedance of the respective sections of the resonator. Linking desirable to choose

length; - for better matching of 8

nators of different wave parameters. All resonators are tuned to the mid bandwidth.

Improving the monofrequency of the filter with the specified oscillatory system follows from the following. Torsional vibrations in the filter converter are the result of the mutual action of two intersecting fields — the residual magnetization field of the ferrite and the field of the excitation coil; therefore, there are longitudinal and transverse components in the oscillations that cause the formation of parasitic passbands if overtone of these vibrations. When one or several resonators with other wave parameters, but tuned to the average frequency of the passband, are included in the resonant system, like all other resonators, parasitic oscillations are further attenuated and they do not pass through the filter output. Thus, the passage of parasitic oscillations through a system consisting of several resonators connected by links depends on the geometry f uz .f

resonant shapes and sizes, i.e., from the wave parameters of the resonators.

Subject invention

An oscillatory system for an electromechanical filter containing series-arranged resonators connected by links, characterized in that, in order to improve the monofrequency of the filter, it is made of a set of at least three types of different resonators, for example a cylinder, a dumbbell and a two-section dumbbell.

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