Патент USA US2129293код для вставки
Sept. 6, 1938. R. WEBER 2,129,293 BAND-PASS FILTER FOR CHANGE OF WAVE Filed March 25‘, 19:57 ' Ilig.i INVENTOR RUDOLF WEBER “7/4 7 ATTORNEY I Patented Sept. 1938 2,129,293 UNITED “STATES PATENT‘ OFFICE nsNn-rsss mmfilz?znmt or wave ' Rudolf Weber, Berlin, Germany, assignor Tele funken Gesellschait fiir- Drahtlose Telegraphic m. 11.11., Berlin, Germany, a corporation oi’ Ger many v Application March 25, 1931, Serial No. 132,901 In Germany March 12, 1936 3 Claims. (01. 178-44) . - The practical ‘demand arises occasionally to ' S3 are closed, while switch Si is opened. The make the band width of receivers changeable in circuit in this condition is shown in Fig. 3. Con side wide limits say, between 1 and 15 k. c. This densers C3 and 04 as well as the resistances WI demand will be made, for instance, if in airplane and W2 are thus rendered inoperative, while 5 ‘receiver apparatus a change is made from beam condensers Cl and 02 no longer operate as cou direction ?nding to the so-called impulse type” pling condensers, but are merely included in the - of direction ?nding. In this'latter instance, the oscillation circuits and avoid detuning, for in impulses, in rectangular shape, must be faith the switch position shown in Fig. 3, each oscilla fully reproduced in the Braun tube so that a tion circuit Ct—L contains an additional con‘ 1° wide-band must be received. denser, namely, the coupling condenser Cl and 10 When a change to such a wide band is made, C2, respectively. In the circuit illustrated in Fig. detuning oi' the oscillation circuits is inevitable. , 3 the coupling between the oscillation circuits is Hence, the condition of untuning would have to effected only by condenser C and it is so loose be corrected by the addition of condensers or that the ensuingband width is limited. But in ' coils. However, switches carrying radio fre lieu of this coupling also any other coupling could quency energy are undesirable because of addi be employed. - is ' tional damping and the requisite shielding. Now, the invention discloses 'a circuit arrange ment in which thesedrawbacks are avoided by of similar, tunable circuits, each including an in- ' reason that the switches carry no radio frequency ‘energy or practically so. In one switch'position, ductance, a variable condenser, a resistance and a. pair or ?xed condensers all connected-in series two paralleled series arrangements of condensers, in the order named, a series coupling condenser connected between. high potential'ends of said inductances, a conductive connection between the low potential ends of said inductances, switch 25 mechanism. individually associated with each tunable circuit for short circuiting the resistance What I claim is: 1. A band-pass ?lter network comprising a pair all of like capacity, serve as a coupler capacity being common'to the oscillation circuits, whereas ‘25 in the other switch position one of these con densers, to avoid detuning, is separately con nected in each or the two oscillation circuits and another suitable coupling is chosen. The invention shall be explained in more detail 30 in what 1ollows_and with reference to the accom panying drawing wherein: and one of the ?xed-condensers when in closed position, and other switch mechanism conjointly associated with both tu'nabl'e circuits and con 80 .nected between the respective junctions of the . , Fig. 1 shows the circuit organization of_ the in vention, short circuited resistance and?xed condenser, whereby the frequency band to be transmitted , 1 Fig. 2 shows the circuit connections obtained 35 when the switches are in the positions illustrated in Fig. 1 whereby transmission of a wide fre quency band is effected,‘ and Fig. 3 shows the cir cuit connections obtained when the switches are in the positions opposite to those illustrated in 40 Fig. l whereby-the transmission of a narrow fre quency band is e?ected. , may be selectively varied within wide limits with out altering the tuning of the circuit, upon open ing the ?rst switch mechanism and closing the second switch mechanism, and ‘vice’ versa.‘ . 2. A band-pass ?lter network comprising a pair of similar oscillation circuits, each compris ing a variable condenser, an inductance, a re sistance and two equal capacities, all connected . Referring'to Fig. 1, there are shown a pair of coupled tuned circuits Cz-L. 1 ‘ in a closed circuit, a coupling condenser con nected between the high potential ends of the In one of ,the switching positions, only the switch Si is closed two inductances, a conductive connection be- ' tween the low potential ends of said inductances' 45 45 so that the four similar condensers CI-Cl con jointly actlike a single condenser C1 of the size‘ a switch connected between low potential ends ' of the individual condensers as shown in Fig. 2. ' The coupling in this connection is'very close, for which reason, to minimize crevasing or the pro-‘ 2 '50 duction of a double peaked resonance curve, damping resistances WI and W2 are included in, the circuit. ‘The coupling insured by condenser C, Fig. l, is only very loose contrasted with the coupling due to C1. 7 58 In the other switch position, switches s: mg n. of the two circuits, between the common termi nals of the resistance and one of the two equal capacities in each circuit, and a switch in each‘ circuit shunting said resistance and seldom of the two equal capacities, the arrangement being such that upon operation of the ?rst switch to closed position and with the two last mentioned switches in open position the circuits are ad lusted to ‘pass a wide band of frequencies, while 2 2,129,293 I the closing of the two last mentioned switches ' coupling condenser and'said parallel coupling and the opening of the ?rst switch adjusts the ‘ capacity being of such magnitudes that the cir circuits to pass a narrow band of frequencies. in cuits are closely coupled to pass a wide frequency each case the oscillation circuits being tuned to band, and means for converting said network _ to one capable of passing a narrow frequency substantially the same resonant frequency. 3. A band-pass ?lter network comprising a band comprising a ?rst switching mechanism for causing the plurality of ?xed condensers to be pair of tunable circuits, each includingan in ductance and a variable condenser, 15. series cou pling condenser connected between the high po 10 tential ends 01’ said inductances, a conductive connection between the low potential ends of said inductances, a plurality of ?xed condensers common to said pair of tunable circuits and serv ing as a parallel coupling capacity, said series come ine?’ective as a parallel coupling capacity and a second switching mechanism individual to each tunable circuit for short circuiting certain 10 01 the ?xed condensers and switching into said tunable circuits others of said ?xed condensers. - RUDOL'E‘ WEBER.