Societe Lignes Telegraphiques Et Telephoniques

Lignes Telegraphiques Et Telephoniques

Societe Telegraphiques Et Telephoniques

Herbert Ernyei

Etienne Langlois

Etienne Langolis

An electromechanical band pass filter includes a plurality of cells in cascade. Each cell comprises two parallel cylindrical bars forming longitudinally vibrating resonators and a flexurally vibrating cylindrical coupler connected between the two resonators. The cell of rank i is dimensioned such that one of its relative limiting frequencies is linked with the frequency of a cell for an electrical low-pass filter by the relationship: ##EQU1##

Electromechanical band pass filters

Each cell includes two longitudinally vibrating cylindrical resonators and a flexurally vibrating coupler connected between the two resonators. The diameter of the coupler is defined by the expression: ##EQU1## wherein: d.sub.r is the diameter of the resonators

Electromechanical filter cells

In an electromechanical filter, poles are obtained by interconnecting an electrical reactance between the input and output of the filter. It is shown that this impedance behaves as a mechanical bridge.

Electromechanical filters

An electromechanical bandpass filter includes at least one real pole consisting of vibrating resonators and couplers between adjacent resonators arranged as filter cells connected in parallel. Each cell includes a coupler and a half of each of the adjacent resonators. At least one bridge extends over at least one resonator and the image mobility of the cells which are spanned by the bridge is equal to the image mobility of the cells in an unbridged electromechanical filter of the same type and having the same passband.

Bridged electromechanical filters

An electromechanical filter comprising resonators interconnected by couplers and at least one bridge strapping over several resonators in which said resonators are longitudinally vibrating, said couplers and bridge are bending and the number of strapped resonators is a multiple of four. Such a filter shows improved phase characteristic within the pass band.

Electromechanical filter structure

The resonance frequency of rod shaped mechanical resonators with a high quality factor such as used in electromechanical filters is obtained by shock exciting the resonator into vibration introduced into a solenoid collecting a voltage induced by said vibration across the solenoid terminals. Said shock is either mechanical or magnetic.

Method of measuring the resonance frequency of mechanical resonators

In an electromechanical filter comprising longitudinally vibrating resonators intercoupled by means of longitudinally vibrating rods, the transducers each consist of two halves located on two flats machined on the same outermost resonator along two parallel planes.

Electromechanical filter

In an electromechanical filter made of longitudinally vibrating cylindrical metal bars connected through bending vibrating coupling rods, the coupling rods are connected to one of the end faces of said resonators. A plurality of resonators are connected to a unitary rod.

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Paris, France

Herbert Ernyei