US2337965A - Coupling network - Google Patents

Coupling network Download PDF

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Publication number
US2337965A
US2337965A US435171A US43517142A US2337965A US 2337965 A US2337965 A US 2337965A US 435171 A US435171 A US 435171A US 43517142 A US43517142 A US 43517142A US 2337965 A US2337965 A US 2337965A
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US
United States
Prior art keywords
impedance
line
network
terminals
coupling
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US435171A
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English (en)
Inventor
Hendrik W Bode
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE473976D priority Critical patent/BE473976A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US435171A priority patent/US2337965A/en
Application granted granted Critical
Publication of US2337965A publication Critical patent/US2337965A/en
Priority to FR948179D priority patent/FR948179A/fr
Priority to GB20990/47A priority patent/GB625722A/en
Priority to NL134148A priority patent/NL77132C/xx
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/40—Artificial lines; Networks simulating a line of certain length
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/38—Impedance-matching networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/14—Control of transmission; Equalising characterised by the equalising network used
    • H04B3/143—Control of transmission; Equalising characterised by the equalising network used using amplitude-frequency equalisers

Definitions

  • This invention relates to wave transmission networks and more particularly to networks for coupling a transmission line to a terminal device or load having la diierent impedance characteristic.
  • yIts objects are to diminish wave reilections in a transmission line terminated by' a load having an impedance characteristic different from that of the 1ine; ⁇ to simplify the ⁇ equalization of the line-attenuation; and to improve the operation of transmission systems in which reactance networks-are employed for the equall zation o1 the line attenuation.
  • the networks of the invention have' the prop-v erty of minimum ⁇ transmission loss consistent with the requirement of physical. realizability.
  • the advantage -in the use of such equalizers arises from the fact that, 'since they contain nojresistance ele- 'i ments, they do not introduce any noise into the system and, therefore, do notlimit the amount of amplification that can be used in the repeaters. 'Iheir use, however, entails a substantial amount of wave reflection at the line terminals,
  • Fig. 1 Vshows application of the invention intheinput circuitsef a telephone repeater
  • Fig.. 2 ireiers to a detail of Fig. 1;'
  • lratio equal to 1. ⁇ /2 from the primary, or line Figs. 5to 10 inclusive,'show additionalforms ⁇ v ff
  • Fig. 1 the coupling network of .the inven.- tion is shown in one of itsforms at I0 coupling f a transmission line Il with areactive ⁇ equalizing ⁇ network I2 in the input circuit of ayfeedbackl amplifier i3.:
  • the showing is representative vof the input side of a repeater vin a multiplex carrier telephone' system using -high frequency carriers.
  • the line Il may be anopen'wire line, a
  • the equalizing network which in the form illustrated comprises a. .tuned transformer ,IL/a sl'eries antiresonant circuit .IB and a shunt ca-f pacity I6, is vso designed as to'produce at its out.- put terminals is, ta' a voltagewhich increases. with frequency in. such manner as ⁇ to compensate fthe attenuation in the line.
  • the ilrst. stage only of the repeater ai'rlpllerv l) is shown together with the feedback impedance Zr, the feedback being of the series type.
  • the l input impedanceof the first ampliier tube is. indicated by the capacity C which represents the electrode capacity and such" other parasitic capacities as are effective between the control grid and the cathode. This capacity isl ordinarily small and its effective impedance is greatly mull ,tiplied by the feedback action.: Consequently, the impedance into which the equalizer works maybe regarded as infinite' or open circuit in so far as it affects the voltage developedfat the output terminals t3, t3', fr
  • the coupling network I0 comprises two. transe formers I1 and il, the two primary windings/1j and the' two secondary windings of which are connected in series. lThese transformers-should and should be designed so 4that throughout the operating frequency range theybehave substantially like Aideal transformers. f For this purv pose the useofmagnetic 'cores of. high permeis advantageous.
  • A... r Transformer I1 has a .voltagetransforxnation side, to thesecondary and transfin'xner, I8 has a voltage transformation 'of the reciprocal value Vzl. Shunt'ed across the secondary put impedance, Z, ⁇ ofequalizer i2 measured at terminals t2, t2'.
  • the coupling network i When they elements have the Values given above, the coupling network i has these properties: When terminated by the equalizer i2 it presents to the line a matching impedance equal toRo; when terminated by the line it presents to the equalizer a constant resistive impedance equal 'to Ro; and .its inclusion between the line and the equalizer reduces the voltage at the equalizer output terminals by a constant amount equal to three decibels at all frequencies. lukewise, if the equalizer and the coupling network are located in the output circuit of a high mpedance amplifier, the currentI delivered to the line is reduced uniformly by three decibels because of the inclusion of the network. This loss is the minimum uniform loss that can be achieved with a physically realizable network.
  • the networks of the invention may taire various forms other than that shown in Fig. 1, certain of which will be described later. All have the properties described above and all have certain characteristic featuresin common. These characteristic features are developed in the following analysis of the principles underlying the operation of the invention.
  • the powerdelivered to the circuit and the power which reaches the line are equal to UFR. and IIoIZRn, respectively, Re denoting the resistance component of the total impedance opposed to the lcurrent I. 'If 'the reactive equalizer matching, absorb some power and the ratio of the two powers Vdeined'above then becomes a measure ofthe loss penalty incurred in effecting an impedance match to the line. From the geometry of the circuit to be givenby Since Z1, Zz and Zaare merely thebranches of the equivalent T ofthe actual circuit, it is not necessary that all of their resistance components R1, R2 and Re be positive for the circuit' as a whole to be physicallyrealizable.
  • Equation I becomes ⁇ Power rat1o1+Ro Rl+ 2) (Rs, X22) (3)
  • the line impedance befmatched by the network may now be introduced. Since the circuitA is assumed to open at terminals ta, t3', this requirement is simply that When these relations are introduced the righthand side of Equation 3 becomes numerically equal to two. Thus-when the limiting condition of physical realizability is just met and the net- 'work matches the line impedance, exactly half of the power applied to the circuit reaches the line. This corresponds to a loss of three decibels and represents the minimum obtainable. Since the reactive equalizer, which was included in the T-network of Fig.
  • Equation 2 can absorb no power, all of the power loss must occur vin the coupling network.
  • the limiting condition of physical realizability set forth in Equation 2 therefore applies to the'coupling network per se in its function of coupling the resistive line to the finite reactive terminal impedance provided by the equalizer.
  • the minimum loss condition hasbeen discussed above in connection with a circuit in which power is supplied to aline from a sourcehaving innnite impedance.
  • This is representative of the output circuit of a high impedance amplifier, for example, one using high impedance pentode tubes;
  • the analysis may be extended to an input circuit'such as shown in Fig. 1 by the principle of reciprocity.
  • the complete termination comprising the coupling network and the equalizer together when subject to the realizability condition may be regarded as one providing the maximum output voltage consistent with impedance matching.
  • Fig. 4 the cou- ;this ratiomay be shown applied to the coupling network itselfbecomes tine algebra.44 They are given by and 'k 'ingtherequired system 'of 'impedanceal One of kthese is illustrated in Fig. 1.
  • ,Qthers are SllOlWll#v l nais tntz'is represented by Z.
  • Zb and Ze the coupling network may bev specified by threerequirements.v The first is the requirement that the impedance presented to the line should equal the line resistance Ro when the structure is terminated at its other end by theequalizer impedance Z..
  • the second is the requirements of minimum vloss,y which when where R., Rs and Re denote the resistance parts o f Z., Zu and Ze.
  • the third is that the impedance presented to the equalizer shallalso equal Ro. which is desirable in'order that the gain charac'- teristic produced by the equalizer may be independent of the presence or absence of the cou pling network.
  • Figs'. 7 to, 10 the arrows -indicate windings l that should be Wound in the same direction on the clore. ⁇
  • the network of Fig. 10 may be derived from the network shown in'Fig. 8 by substituting a single windingtappedat its mid-point for the two primary windings.
  • the circuit configurations i and the magnitudes of thetransformation ratios are so chosen that the value of the resistance is subject to a step-up of two toone from the line terminalsto thel output terminals, while the value of the reactive impedance4 is decreased in the same ratio.v
  • ywide frequency range comprising a four-terminal network having open circuit driving point impedances lat its line and load terminalssubstanwiesiectively, and an open circuit transfer imped- 'Y -note the open circuittransier impdance.
  • y'l'.'hese ancez' substantially equal to 1 said rietworkincluding'a resistor, a reactor having-fan* impedance inversely related. to Z, and .transforming ymeans whereby. the effective imvparlantes 'of'said resistor and saidreactor meas- ⁇ v,ur-ed at the network terminals are subject to reciprocally related transformations.
  • the wide frequency-range comprising a resistor, a reactive impedance inversely related to the prescribed impedance Z, and a plurality of transformer means having diierent transformation ratios coupling said resistor and said inverse impedance, to the input and output terminals of the network, the impedances of the said network elements and theytransformation ratios of said transformer means being proportioned to make the open circuit driving point impedances ofthe network at the line and load i terminals substantially equal to respectively, and to make the open circuit trans fer impedance substantially equal to terminals of the network, the connections of the said transformer means being so arranged that the impedancesof said resistor and said inverse' impedance are subject to reciprocally related impedancetrans'formations .between the line and load terminals of the network, and the network elements being proportioned to make the open circuit transfer and driving point impedances atl the line and load terminals substantially equal to respectively, at all frequencies'in a wide range.
  • a four-terminal coupling network for cou pling a line of resistive impedance Ro toa termi;- nal device having a prescribed frequency dependent reactive impedance of value Z comprising a pair of transformers having their primary windings connected in series between the line terminals of the network and having their secondary windings connected in series between the other terminals of the network, one of'said transformers having a voltage transformation ratioof 1 :V
  • a network for coupling a line of resistive impedance Ro to a terminal device having areactive impedance of value Z comprising a transformer having a secondary winding arranged for connection to said-terminal device and a centrally tapped primary winding, the two portions of vsaid primary winding and said secon d ary winding having turns in the ratios 1:1: ⁇ /2, a pair of input terminals for connection to the line, a resistance of value 'Rnconnected between one oi' said terminals and one end of said primary winding, a reactive impedance of value connected between said one terminal and the center tap of said primaryvwinding and a connection impedancesin parallel be- @o from the other of said-terminals to the other end of said primary Winding.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Filters That Use Time-Delay Elements (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US435171A 1942-03-18 1942-03-18 Coupling network Expired - Lifetime US2337965A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE473976D BE473976A (xx) 1942-03-18
US435171A US2337965A (en) 1942-03-18 1942-03-18 Coupling network
FR948179D FR948179A (fr) 1942-03-18 1947-06-18 Réseau de couplage
GB20990/47A GB625722A (en) 1942-03-18 1947-08-01 Improvements in or relating to coupling networks
NL134148A NL77132C (xx) 1942-03-18 1947-08-15

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US435171A US2337965A (en) 1942-03-18 1942-03-18 Coupling network

Publications (1)

Publication Number Publication Date
US2337965A true US2337965A (en) 1943-12-28

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Family Applications (1)

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US435171A Expired - Lifetime US2337965A (en) 1942-03-18 1942-03-18 Coupling network

Country Status (5)

Country Link
US (1) US2337965A (xx)
BE (1) BE473976A (xx)
FR (1) FR948179A (xx)
GB (1) GB625722A (xx)
NL (1) NL77132C (xx)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474238A (en) * 1945-06-27 1949-06-28 Myron Y Eck Single null loop antenna
US2669698A (en) * 1951-04-26 1954-02-16 Collins Radio Co Radio frequency matching transformer
US3155927A (en) * 1960-09-12 1964-11-03 Gen Electric Bridged-t termination network
US6140849A (en) * 1998-08-07 2000-10-31 Trask; Christopher Active double-balanced mixer with embedded linearization amplifiers
US6242964B1 (en) 1999-11-15 2001-06-05 Christopher Trask Low-distortion lossless feedback double-balanced active mixers using linearity augmentation
US6393267B1 (en) 1999-07-07 2002-05-21 Christopher Trask Lossless feedback double-balance active mixers
US6400936B1 (en) 1999-11-15 2002-06-04 Christopher Trask Low-noise lossless feedback double-balanced active mixers
DE10248471A1 (de) * 2002-10-17 2004-05-06 Infineon Technologies Ag Übertrager-Schaltungsanordnung

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474238A (en) * 1945-06-27 1949-06-28 Myron Y Eck Single null loop antenna
US2669698A (en) * 1951-04-26 1954-02-16 Collins Radio Co Radio frequency matching transformer
US3155927A (en) * 1960-09-12 1964-11-03 Gen Electric Bridged-t termination network
US6140849A (en) * 1998-08-07 2000-10-31 Trask; Christopher Active double-balanced mixer with embedded linearization amplifiers
US6393267B1 (en) 1999-07-07 2002-05-21 Christopher Trask Lossless feedback double-balance active mixers
US6242964B1 (en) 1999-11-15 2001-06-05 Christopher Trask Low-distortion lossless feedback double-balanced active mixers using linearity augmentation
US6400936B1 (en) 1999-11-15 2002-06-04 Christopher Trask Low-noise lossless feedback double-balanced active mixers
DE10248471A1 (de) * 2002-10-17 2004-05-06 Infineon Technologies Ag Übertrager-Schaltungsanordnung
US20040124959A1 (en) * 2002-10-17 2004-07-01 Infineon Technologies Ag Transformer circuit arrangement
US6828893B2 (en) 2002-10-17 2004-12-07 Infineon Technologies, Ag Transformer circuit arrangement

Also Published As

Publication number Publication date
BE473976A (xx)
FR948179A (fr) 1949-07-25
NL77132C (xx) 1955-02-15
GB625722A (en) 1949-07-01

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