US1687062A - Filter for high-frequency oscillations - Google Patents

Description

Oct. 9, 1928.

H. J. J. M. DE R. DE BELLESCIZ E FILTER FOR HIGH FREQUENCY OSCILLATIQNS Filed June 2, 1925 vwamtoz H-J-J- DER. 'DE-BELLESCIZE @51 M15, Elam/m1;

FREQUENCY Patented 9, 1928.

UNITED STATES 1,687,062 PATENT OFFICE.

HENRI JEAN JOSEPH MARIE DE REGNAULI) DE BELLESCIZE,-OF TOULON, FRANCE.

FILTER FOR HIGH-FREQUENCY OSCILLATIONS.

Application filed June 2, 1923, Serial No. 642,883, and in France June 8, 1922.

The present invent on relates to animproved method of coupling a plurality of resonant circuits cascade fashion, and more particularly relates to securing a purely inductive coupling between such circuits. My invention is illustrated in the attached drawing in which i Fig. 1 shows an arrangementof tuned circuits in cascade as used in radio signalling systems,

Fig. 2 shows a similar system as con= structed in accordance with my invention,

Fig. 3 shows such a system provided with a closed antenna, and

Fig. 4c is a comparison of resonance curves of the old and new arrangement.

The disposition in cascade of several tuned-or resonant circuits has been resorted tOfOr a long while in the construction of receiving apparatus in wireless work. This arrangement which at equal syntony, per-" mits of reducing. the duration of establishment and extinction of oscillations, shows a tendency of becoming more general in use and application under the name of filters. Now, in order to realize good results it is indispensable that the coupling existent between the two consecutive resonators, no

matter of what sort they may be, should not be at the same time inductive and electrostatic (or capacitative).

In Fig. 2 of the drawing in which is illustrated, by wayof example, my invention applied to a filter,C,, represents a conventional aerial connected to ground through the inductance L and the coil m. The coil m is in inductive relation to the coil M to induce oscillations, corresponding to those in the l antenna circuit, in the resonant circuit M, 0,.

This latter circuit is inductively connected in cascade to the resonant circuit L G which in turn is inductively coupled to the resonant circuit L C The relation of the coupling coils in each ofthese circuits is is not confined to the modes of execution as exactly similar, and it will be necessary'tO describe the arrangement with respect to the circuit M, C, alone.-

The coupling coils m,M' are placed end to end in. inductive relationship and their adjacent ends are grounded to fix the potential at these points. That is, the point Q in the coil M is grounded and the point 0 in, the coil m is grounded. From this arrang'ement. it follows that the potential between ground and any point in the coil M is proportional to the distance between that point and the coil m. In other words, the higher the potential of a point in the coil M above ground potential, thegreater will be its dstance from the coil m and as the capacity between the coils is inversely proportional to the distance separating them the capacitative efiects along coil M decrease as the potential increases, thereby reducing the capacitative coupling between the coils M, mto a minimum.

The arrangement in Fig. 3 is substantially the same as that in Fig. 2, except that the aerial C is replaced by a closed antenna circuit comprising the inductance L and the condenser C The operation of this device is, of course, the same as that of the device riod of excition at the input end of the filter device is caused to be varied, the resonance curve observed at the output end assumes the regular shape of curve a (Fig. 4) whereas when cutting off the various equipotential connections previously described (which substantially is tantamount to the employment of the customary mode of mounting as illustrated in Fig. 1), a curve is obtained having a shape substantially as curve I), Fig. 4.

The imput resonator, i. e., resonant circuit,

may consist of either an open oraclosed antenna (Fig. 2 and Fig. 3 respectively). The

resonators, with the exception of the antenna, can be enclosed in a metal cage X, which sh elds and protects them from the direct action of Hertian waves. The said metallic box could also be subdivided or part'tioned by means of partitions Y likewise consisting of metal, to the end of enclosing each coil L in its own Faraday cage,

which'safeguards it from residual or stray electrostatic actions due to other coils. cages themselves could earthed.

The invention itself, be it Well understood,

The

described my invention, what I secondary coupling coil, the primary one of said circuits being connected end to end with 'mon connection of the primary and secondary.

2. In a cascade circuit arrangement, a plurality ofresonant circuits, each having primary and secondaryinductance coils, one end of each primary and its associate secondary in the next successive resonant cirncemcee cuit being connected to a common ground,

the arrangement being such that the potential at any point in said inductances is directly proportional to the distance between said point and the common ground connection, thereby substantially reducing the distribu tive capacity between said primary and secondary inductance coils.

HENRK JEAN JOSEPH MARIE cle REGNAULD de BELLESCIZE.

Images