US2226686A - High frequency transmission network - Google Patents

High frequency transmission network Download PDF

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Publication number
US2226686A
US2226686A US174759A US17475937A US2226686A US 2226686 A US2226686 A US 2226686A US 174759 A US174759 A US 174759A US 17475937 A US17475937 A US 17475937A US 2226686 A US2226686 A US 2226686A
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United States
Prior art keywords
network
transmission line
impedance
line
high frequency
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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
US174759A
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English (en)
Inventor
Alford Andrew
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.)
Mackay Radio & Telegraph Co
MACKAY RADIO AND TELEGRAPH Co
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Mackay Radio & Telegraph Co
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Filing date
Publication date
Priority to FR49942D priority Critical patent/FR49942E/fr
Application filed by Mackay Radio & Telegraph Co filed Critical Mackay Radio & Telegraph Co
Priority to US174759A priority patent/US2226686A/en
Priority to GB31442/38A priority patent/GB517052A/en
Priority to DEI3376D priority patent/DE932025C/de
Application granted granted Critical
Publication of US2226686A publication Critical patent/US2226686A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/02—Coupling devices of the waveguide type with invariable factor of coupling
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/30—Arrangements for providing operation on different wavebands
    • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
    • H01Q5/314—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors
    • H01Q5/335—Individual or coupled radiating elements, each element being fed in an unspecified way using frequency dependent circuits or components, e.g. trap circuits or capacitors at the feed, e.g. for impedance matching
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/50—Feeding or matching arrangements for broad-band or multi-band operation

Definitions

  • My invention relates to reentrant networks for modifying the transmission characteristics of a high frequency transmission line and more particularly to the use of composite reentrant networks for effecting a filtering action in the line circuit, an impedance matching between sections of the line or other useful functions.
  • This invention constitutes a further development of reentrant network circuits such as disclosed in my application, Ser. No. 118,886, filed January 2, 1937, issued as Patent No. 2,190,131, on February 13, 1940.
  • a reentrant network circuit was disclosed in which filtering action, phase modification and impedance matching at certain frequencies may be accomplished by suitably dimensioning and proportioning the parts of the reentrant loop circuit.
  • means are provided comprising an impedance or equivalent means connected across a point in such a reentrant network, whereby the network may be so. modified as to produce the desired characteristics even though the dimensions do not correspond exactly tothe requirements set forth in the prior application.
  • the additional impedance across a point of a reentrant network may be used to afford a filter circuit for other frequencies than those upon which the reentrant loop by itself is effective.
  • a principal object of my invention is to provide a structure which may be used as a highly efiicient transformer, filter or other wave modifying device which is simple in structure and easily adjustable.
  • Another object of my invention is to provide means for adjusting a reentrant network for a particular frequency by means of an adjustable impedance connected thereacross.
  • Fig. 1 illustrates one form. of the network using an open line as the impedance,.
  • Fig. 2 illustrates a modification of Fig. 1, using a closed line as the impedance element
  • Fig. 6 illustrates an application of a variable condenser for particular use with a concentric cable conductor
  • Fig. '7 illustrates a circuit in which the reentrant loop network in accordance with my invention is used to obtain certain useful data
  • Figs. 8 and 9 are curves plotted from test data obtained with a network similar to that shown in Fig. 7.
  • Fig. 10 illustrates a network used as an im pedance matching transformer, I
  • Figs. 11 and 12 illustrate useful applications of the double filter network
  • Fig. 13 illustrates an application of a network in accordance with my invention as an insulating support
  • Fig. 14 illustrates an application as an insulating spreader.
  • IIII represents a source of high frequency alternating current
  • I03 is a load connected over transmission line I05 to the source.
  • reentrant-network shown generally at I06.
  • This network comprises three arms, I01, I08, I09, forming together a closed loop.
  • arm I01 comprises a section of transmission line I05.
  • an additional impedance III which may comprise an open-ended transmission line, as shown in this figure.
  • Arms I08, I 09 join with transmission line I05 and arm I01 at points H3, H5, respectively.
  • Arms I01, I08, I09 together form a reentrant loop circuit which if suitably dimensioned will serve as a wave filter or a Wave modifying device as fully described in my copending application referred to above.
  • a filter network is provided which may be sharply tuned to provide the desired relationship for filtering or impedance transformation regardless of I the exact relationship of the arms With respectto the frequency. This is accomplished by connecting across the loop at a suitable point an impedance represented by the open line III.
  • the arms I01, I08, I09 may be represented by 02, 61 and 03, respectively, in which 0 expresses the length of the various arms in terms of wavelength.
  • The. length in Wavelengths of open transmission line I I I may be'represente'd by of a network fan 2 sin 2 (1) an A sin 0 sin 0 in which 01, 02 and 63 have the values given above and x in the wavelength of the energy being transmitted.
  • Fig. 2 represents a network in accordance with this arrangement.
  • the various elements corresponding to those in Fig. 1 are indicated by similar reference characters; however, at a point in line I I I equal to is inserted a short-circuiting bar 2II forming a closed line. Since the short-circuit is at a termination equivalent to a quarter wave transmission .line the network may be grounded at this point and thus will serve as a means for grounding other frequencies introduced on the line.
  • Figs. 1 and 2 I have shown the reentrant network in the form of a triangle and the impedance in the form of open or closed line sections, it should be understood that since the impedance may take other forms, an impedance element such as indicated by the inductance at 3II of Fig. 3, may be used to replace the line section. This impedance should be so formed and adjusted as to produce the equivalent effect of the open or closed sections as indicated above. It is clear that any suitable desirable form of impedance may be substituted for the transmission line section so long as the equivalency of the impedance is maintained.
  • Fig. 4 I have shown the network in the form of two semi-circular lines connected to the transmission line. It is clear that in this case the arms 40B, 409 may be measured to the point M0 in a manner similar to that explained in detail in connection with Fig. 1. It is furthermore pointed out that the particular form and shape of the reentrant network is not material since it is only necessary that the proper relation among the several arms thereof be maintained. In each instance the lengths 01, 02 and 63 are to be measured along the conductors forming the various arms of the loop.
  • Fig. 5 I have illustrated a condenser connected across point 5
  • Equation 1 If 01+03+02 is made nearly equal to 360 and 01 and 03 are neither equal to 180 nor zero, then the right hand side of Equation 1 is quite small. Moreover, if 01+03+0z is slightly less than 360 while 01-l-63-02 is such that co-sine is small and is positive so that the length of the open ended section attached at point 5I0 is small. That means that the network may be brought into condition of exact cut-ofl. by connection of a small capacity across the line at 5I0. Thus a small condenser such as 5
  • Fig. 6 is shown an application of this principle to a network made from lengths of. concentric transmission line.
  • 60.5 indicates the transmission. line to which is' joined at points 613, 6 l a reentrant loop formed of another concentric line conductor.
  • compensation for the error may be made by use of a condenser plate 62
  • This means maybe used for ready adjustment of a filter circuit and provides a means for easily making necessary or desired changes in tuning. This is particularly useful in concentric conductor circuits since it is quite diificult to readily change the connections at such points as 613, M5 to effeet the desired adjustment without use of the additional impedance.
  • a network such as shown in Fig. 6 is employed for stabilizing or substantially controlling the frequency of an ultra-high frequency oscillator.
  • the concentric tube may have to be maintained at a constant temperature and for that reason may be either wrapped with a layer of insulating material or with a wire through which heating current may be passed, or it may merely be well insulated and placed in a compartment maintained at a constant temperature. In any such event, however, access to the network is pretty much obstructed so that the length of the elements cannot easily be changed.
  • a means may be provided for easily completely tuning the circuit to the precise desired frequency.
  • composite reentrant network as a filter circuit has been fully described above in connection with Figs. 1 to 6, inclusive. However, this network is capable of a number of other uses as will bemore fully set out in a particular consideration of Figs. 7 to 13, inclusive.
  • I20! represents a source of high frequency energy.
  • the transmission line I 202 terminated by impedance load I203.
  • a composite reentrant network I284 comprising the reentrant network A, B, C, A and the additional terminal impedance of length I lettered CD in the drawings. If this network is chosen so that AC equals CB, then it has been found that with certain adjustments of the length of the line CD, various effects of the standing wave distribution may be observed with changes in the length of the additional transmission line CD.
  • the distance AB corresponds to the dimension 62 of Fig. 1, while AC corresponds to the dimensions 01 and CB to the dimension 63 of that figure.
  • the apparatus 7 was set up with particular dimensions of ACE in terms of the wavelength and the length of CD the maximum and minimum values of the standing wave. Likewise, measurements were taken of the distance it of the standing wave minimum from the point of junction of the reentrant network. These measurements were made for three different dimensions of network, as follows: (1)- With ACB equal to substantially .153 wavelength and the distance AB equal to substantially .93 wavelength. (2) With ACB equal to substantially .153 wavelength and the AB equal to substantially .056 wavelength. (3) With ACB equal to substantially .112 wavelength and AB equal to substantially .056 wavelength.
  • Figs. 8 and 9 were obtained.
  • the curves of Fig. 8 illustrate the change in the standing wave maximum to minimum ratio designated by Q, as abscissa plotted against the length l of the added impedance measured in the wavelength as ordinates. 'From these curves it is evident that not only does the standing wave ratio vary with changes in length Z but likewise for each such composite network there is a point in which the standing wave ratio obtained is equal to 1. latter feature constitutes a valuable principle for certain uses that may be made of the network.
  • Fig. 9 the curves I, 2 and 3 illustrate the distance it, that is the distance of the standing wave minima from the network in terms of wavelength, as abscissa, against the length I of the impedance transmission line in wavelengths as ordinate.
  • any network which can be used to introduce standing waves into a transmission line which is terminated in a surge impedance may be used to match a transmission line normally having standing waves thereon. It is clear that this network produces a useful system to be used in impedance matching of transmission lines. For example, if a transmission line has a standing wave ratio of two, a network may be designed to match this impedance, in accordance with my invention. Taking,for example, the standing wave ratio Q equals 2, as stated above, a network may be devised in accordance with the above disclosure so that it will suit anyv or distance it may then be obtained from the curves illustrated in Fig. 9.
  • Fig. 10 is illustrated a system in which the This network in accordance with my invention is used as an impedance matching device.
  • 'IOI constitutes a high frequency A. C. source and I02 is a load connected thereto.
  • An impedance network 106 designed in accordance with the method outlined above is included in transmission line I05.
  • the impedance unit is thus so designed that the impedance looking into the device at point H3 is equal to the surge impedance of the transmission line I05.
  • this network is properly located on the transmission line in accordance with some such curves as those illustrated in Fig. 11 and thus no standing waves will remain on the portion of the line shown to the left of network I05.
  • Fig. 11 is illustrated by way of example one system using the double frequency filter circuit described in the earlier paragraphs of this specification.
  • 90I represents a source whichmay be a receiving antenna and 902 represents a load which may be a radio receiver.
  • the receiving circuit 90I, 902 may be located in the vicinity of two transmitters operating at frequencies other than that to be received, as indicated at 900, 903. In this arrangement difficulty may be encountered in receiving the desired signals on EDI and receiver 902 due to the strong signals induced therein by reason of the proximity of the two transmitters. In this case, use may be made of the several filtering features as disclosed above.
  • the double frequency filter 904 may be constructed so as to present substantially complete cut-off at frequencies f2 and
  • Fig. 12 is shown an application of the double frequency filter to an antenna system in which a single antenna IOI is used to transmit two frequencies f2 and is from transmitters I002, I003, respectively, and to operate simultaneously to receive signals on receiver I004 at frequency ii.
  • filters IOI2, IOI3, IOI4 are associated, respectively, with IBM, I003, I004.
  • Filter IOI2 is tuned to exclude frequencies f1 and is while presenting substantially no impedance to f2, while filter IOI3 is tuned to exclude frequencies f1 and is while permitting passage of is, while filter IOI4 is tuned to exclude frequencies is and is while permitting passage of frequency f1. It is thereby made possible to operate upon a single antenna with these three frequencies without endangering interference of the signals in the different circuits.
  • receiver I004 may be replaced by another transmitter operating at a third frequency or the transmitters I002, I003 may be replaced by receivers operating on the separate frequencies. It is thus made possible to operate simultaneously at different frequencies either in transmission or reception Without endangering mutual interference in the respective circuits.
  • I30I represents a high frequency transmission line connecting together high frequency apparatus I302'and I306.
  • This apparatus may be, for example, a high frequency transmitter, a high frequency receiver, or an antenna for either receiving or transmitting high frequency energy.
  • Such apparatus as I302 is often mounted at a level different from another portion of the transmission line I30 I, for example, it may be mounted at a higher point. Because of this difference in level of mounting it is necessary to introduce a bend or angle in the transmission line, as indicated at I303. In order to introduce such an angle into the transmission line it is necessary that the line be fastened at I303 to some support, such as I304.
  • the insulating system described in connection with Fig. 13 may be used at the same time as a supporting means and a spreader if the parts of the reentrant loop are made of stiff conductors.
  • An example of such an arrangement is shown in Fig. 14.
  • the transmission line is indicated at I40I.
  • a network I405 is inserted.
  • Thisnetwork may be dimensioned in accordancewith the disclosure above, so as to serve in place of an insulator, and is made of rods or tubing so as to give a sufiicient support.
  • the network is preferably designed with a short circuiting bar I406, similar to that shown in connection with Fig.
  • the rigid network may be designed to serve in place of an insulator, it is clear that a network serving as a filter or an impedance transformer, may likewise be made of a stiff material so as to serve simultaneously as a support and spreader 'for the transmission line conductors.
  • a composite transmission modifying network foruse in a high frequency circuit comprising a first uniform conductor, a second uniform conductor connected at its ends to the ends of said first conductor, and an impedance element connected to one of said conductors at a predetermined point intermediate the ends thereof.
  • a high frequency transmission circuit comprising a two conductor transmission line, 'a pair of conductors each of said conductors having its ends connected to spaced points on a corresponding conductor of said transmission line, said transmission line being continuous between said spaced points, and an impedance means connected to an intermediate point on said pair of conductors.
  • a high frequency transmission circuit comprising a two conductor transmission line, a pair of conductors each of said conductors having its ends connected to spaced points on a corresponding conductor of said transmission line, said transmission line being continuous between said spaced points, and an impedance means connected to an intermediate point on said pair of conductors, the sum of the lengths of said pair and the portion of the transmission line included between said predetermined points of connection being equal to 360 electrical degrees.
  • a high frequency transmission circuit comprising a two conductor transmission line, a pair of conductors each of said conductors having its ends connected to spaced points on a corresponding conductor of said transmission line, said transmission line being continuous between said spaced points, and an impedance means comprising a conductor pair connected to an intermediate point on said pair of conductors.
  • a high frequency transmission circuit comprising a two conductor transmission line, a pair of conductors each of said conductors having its ends connected to spaced points on a corresponding conductor of said transmission line, said transmission line being continuous between said spaced points, an impedance means comprising a conductor pair, and a short circuiting bar connected across said conductor pair at a predetermined distance from said intermediate point.
  • a high frequency transmission circuit comprising a two conductor transmission line and a filter network connected to said line comprising, a first conductor pair connected to said transmission line, a second conductor pair connected to said transmission line at a point spaced from the connection point of said first conductor pair, said first and second pairs being serially connected, and an impedance means connected at the junction of said serially connected pairs.
  • a uniform two conductor transmission line comprising two conductors each of said conductors having both of its ends connected at each of their ends respectively to equally spaced points on a conductor of said transmission line, said transmission line remaining continuous between points of connection and an impedance means connected to predetermined points on said loop circuit conductors.
  • a high frequency circuit according to claim 8 in which the portions of said loop conductors between said predetermined points and said transmission line are equal and said impedance means comprises a section of two conductor line, dimensioned to produce a desired reaction in said line.
  • a high frequency circuit according to claim 8 in which said pair of conductors are relatively rigid, and said impedance means comprises relatively rigid conductors firmly attached thereto, and a short circuiting bar bridged across said conductors at a predetermined distance from said loop conductors.
  • a transmission line a transmission line, a source of high frequency connected to one end of said line, a load connected to the other end of said line, and means connected to said transmission line intermediate the ends of said line comprising, a loop connected to two spaced points in said line, and an impedance means connected to an intermediate point on said loop for matching the impedance of the remainder of said line and said load to said source.
  • a method of matching the impedance of a load to a transmission line, using a reentrant loop circuit and an impedance coupled thereto which comprises, choosing the desired dimensions for said loop, measuring the ratio of the standing wave maximum to the standing wave minimum existing on said line, and the relative location of said maxima and minima along said line, determining the value of said impedance from said standing wave ratio and said desired dimensions, connecting said impedance across said loop at a predetermined point thereon, and connecting said assembled loop and impedance to said transmission line at a point determined by the value of said impedance and the position of said standing waves on said line.
  • a transmission line extending in one direction, a second transmission line extending in a direction at an angle to said first transmission line and connected serially thereto, and means for connecting said transmission lines to a support at the junction thereof, comprising a conductor connected to one transmission line, a second conductor connected to said second transmission line, the other ends of said conductor being serially joined, and another conductor connected to the junction point of said first and second conductors, said conductors, the portion of said transmission line therebetween and said junction connected conductor being so dimensioned and arranged that they present substantially no impedance in the transmission line, and means for connecting the other end of said junction connected conductor to a support.
  • a high frequency apparatus designed to operate at a given frequency
  • a trans mission line connected to said high frequency

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  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)
US174759A 1937-11-16 1937-11-16 High frequency transmission network Expired - Lifetime US2226686A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
FR49942D FR49942E (fr) 1937-11-16
US174759A US2226686A (en) 1937-11-16 1937-11-16 High frequency transmission network
GB31442/38A GB517052A (en) 1937-11-16 1938-10-31 High frequency transmission networks
DEI3376D DE932025C (de) 1937-11-16 1938-11-18 Hochfrequenznetzwerk zur frequenzabhaengigen Kopplung zweier Schaltteile

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US174759A US2226686A (en) 1937-11-16 1937-11-16 High frequency transmission network

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US2226686A true US2226686A (en) 1940-12-31

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DE (1) DE932025C (fr)
FR (1) FR49942E (fr)
GB (1) GB517052A (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2480172A (en) * 1943-11-05 1949-08-30 Int Standard Electric Corp Radio antenna
US2512704A (en) * 1943-12-06 1950-06-27 Int Standard Electric Corp Arrangement for coupling wide frequency band antennae to transmission lines
US2644928A (en) * 1948-06-09 1953-07-07 Rca Corp Directional transmission line transducer
US2773244A (en) * 1952-08-02 1956-12-04 Itt Band pass filter
US3096493A (en) * 1959-07-23 1963-07-02 Gen Electric Co Ltd Four-terminal electric networks
US4999642A (en) * 1988-03-01 1991-03-12 Wells Donald H Transmission line coupling device with closed impedance matching loop
US5083136A (en) * 1989-11-16 1992-01-21 Wells Donald H Transmission line coupling device with closed impedance matching loop
US5463405A (en) * 1994-05-20 1995-10-31 Valor Enterprises, Inc. Cellular telephone coupling network

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2480172A (en) * 1943-11-05 1949-08-30 Int Standard Electric Corp Radio antenna
US2512704A (en) * 1943-12-06 1950-06-27 Int Standard Electric Corp Arrangement for coupling wide frequency band antennae to transmission lines
US2644928A (en) * 1948-06-09 1953-07-07 Rca Corp Directional transmission line transducer
US2773244A (en) * 1952-08-02 1956-12-04 Itt Band pass filter
US3096493A (en) * 1959-07-23 1963-07-02 Gen Electric Co Ltd Four-terminal electric networks
US4999642A (en) * 1988-03-01 1991-03-12 Wells Donald H Transmission line coupling device with closed impedance matching loop
US5083136A (en) * 1989-11-16 1992-01-21 Wells Donald H Transmission line coupling device with closed impedance matching loop
US5463405A (en) * 1994-05-20 1995-10-31 Valor Enterprises, Inc. Cellular telephone coupling network

Also Published As

Publication number Publication date
GB517052A (en) 1940-01-18
FR49942E (fr) 1939-09-25
DE932025C (de) 1955-08-22

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