US2147809A - High frequency bridge circuits and high frequency repeaters - Google Patents

High frequency bridge circuits and high frequency repeaters Download PDF

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Publication number
US2147809A
US2147809A US140594A US14059437A US2147809A US 2147809 A US2147809 A US 2147809A US 140594 A US140594 A US 140594A US 14059437 A US14059437 A US 14059437A US 2147809 A US2147809 A US 2147809A
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United States
Prior art keywords
loop
circuit
high frequency
points
bridge
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Expired - Lifetime
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US140594A
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English (en)
Inventor
Alford Andrew
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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 NL63339D priority Critical patent/NL63339C/xx
Application filed by Mackay Radio & Telegraph Co filed Critical Mackay Radio & Telegraph Co
Priority to US140594A priority patent/US2147809A/en
Priority to DEI3363D priority patent/DE920730C/de
Application granted granted Critical
Publication of US2147809A publication Critical patent/US2147809A/en
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Expired - Lifetime legal-status Critical Current

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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
    • H01P5/12—Coupling devices having more than two ports
    • H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
    • H01P5/19—Conjugate devices, i.e. devices having at least one port decoupled from one other port of the junction type
    • H01P5/22—Hybrid ring junctions
    • H01P5/225—180° reversed phase hybrid rings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00—Coupling devices of the waveguide type
    • H01P5/12—Coupling devices having more than two ports
    • H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port
    • H01P5/19—Conjugate devices, i.e. devices having at least one port decoupled from one other port of the junction type
    • H01P5/22—Hybrid ring junctions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication

Definitions

  • My invention relates to high frequency units particularly for use as high frequency bridge circuits and in high frequency repeaters. Because of the extreme simplicity of the system and the ease with which very accurate adjustment may be made, this system is particularly useful when dealing with extremely high frequencies, for example in the neighborhood of 2 megaeycle's;
  • My invention makes use of reentrant loop cir- 0 cults, and in its broadest form comprises a reentrant loop circuit coupled to some source of high frequency so that at points on said loop there may be produced voltage nodes or current nodes which may be used as points for coupling to the desired apparatus or circuit.
  • Such reentrant loop units may be then used for extremely accurate comparison of impedances or for coupling together circuits in conjugate relation in a manner similar to that used in the conventional hybrid coil circults It is an object of my invention to provide such a unit which may be used readily in bridge circuits and other high frequency apparatus.
  • Fig. 3 illustrates an embodiment of my invenment
  • FIG. 4 illustrates an embodiment of my invention which comprises a high frequency repeaterv
  • Fig. 5 illustrates an embodiment of my invention applied to a two-way communication system
  • Figs. 6 and 7 illustrate modification of the circult shown in Fig. 2.
  • 'i l' represents a source of radio frequency energy connected by transmission lines it, it with reentrant loops M, It at junction points M, 23. Points 25,
  • Fig. 2 is substantially the same as Fig. 1, with the exception that the loops are transposed at a point 3i. As a consequence of this transposition the currents in this circuit add at points 25, 21 and the voltages cancel, producing an absolute voltage node. Since the transmission lines in Fig. 2 are assumed to be equal in all respects, as stated in connection with Fig. 1, the voltage across the line at 25, 21 would be precisely zero if there 40 were no reflection at the point of transposition 3
  • the voltage across points 25, 21 is extremely small compared to the voltage across points a, a, b, b, which are spaced a distance equal to a fraction of a wavelength from points 25, 21. It is this phenomenon which renders this circuit particularly useful as a bridge.
  • a sensitive meter such as, for example, a vacuum tube voltmeter
  • the voltage indicated by meter 35 will be very small, substantially zero.
  • a load such as 31, having an impedance Z1
  • the balance of the bridge will be upset due to reflections along the arms 21, a, 2
  • the load should be connected at a point distant a substantial fraction of a quarter wavelength from the voltage nodal points 25, 21.
  • a is gradually increased from zero with a corresponding and opposite increase of distance between the voltage nodal points 25, 21 and b, b, the voltage across the line at points a, a gradually increases. Since points 25, 21 represent a voltage node, the voltage across a point a small distance from this node will be small and consequently a very small amount of current can be diverted into the high impedance load 31.
  • the loop circuit I1, I9 is not most sensitive with respect to unbalance whenthe distance between the load and the voltage nodal points 25, 21 is equal to a quarter wavelength. The reason for this is that when the load is located at a quarter wavelength from the voltage nodal points, such a large amount of current is diverted into the load that only a small fraction is able to penetrate as far as the points 25, 21 across which the meter 35 is connected.
  • Fig. 3 is illustrated an application of this reentrant loop bridge circuit for impedance measurement. Because of the extreme simplicity and accuracy of this bridge particularly in the higher radio frequencies, this device is a useful tool for measurements of all kinds.
  • IN represents a radio frequency source connected through transmission lines I 08, I05 to a bridge loop arrangement I01, I09 constructed in substantially the same manner as that described in connection with Fig. 2.
  • a suitable sensitive voltmeter I2I is coupled over balanced transformer I23 to the voltage nodal points I I5, I I1 of the loops I01, I09.
  • the loops I01, I09 are shown as transposed at an impedance II3 to compensate for the reflection at the transposition point.
  • H1 Connected across loops I01, I09 at points a,,a', b, b equally spaced from points H5, H1 are two identical shielded transformers I25, I21 through which the various elements to be tested may be coupled.
  • the loop bridge as shown may then be used for comparing any desired impedances, such as variable or fixed condensers, tuned circuits or any other equipment.
  • equal lengths of identical cables I29, I3I may be connected to the transformer and may be employed for comparing two grounded impedances, one or both of which may be at substantially large distances from the loop bridge.
  • FIG. 4 Another application of a somewhat different character of the loop circuit is shown in Fig. 4.
  • the loop is used somewhat in the manner of a hybrid coil for coupling a repeater amplifier to a transmission line.
  • the reentrant loop circuit comprises two loops 201, 209 constructed in the same manner as that shown in Fig. 2.
  • An amplifier 208 is coupled with its input across points 2
  • a is connected a transmission line 239 which is coupled across the line 2 connected between stations 243 and 245.
  • This line then presents a definite impedance Z1, and in order that the value of this impedance will not be momentarily disturbed this line should be made refiectionless by the use of well known matching devices.
  • a is an impedance element 25I which has an'impedance Z2 equal to Z1. It can be seen that in this system energy from line 24I may be transmitted over line 239 to the input of amplifier 208, and the amplified energy transmitted back over 239 to 2 in amplified form. Due to the loop bridge 201, 209 none of the energy from the output of amplifier 208 can be transmitted back to the input.
  • a repeater amplifier coupling is made in the line 2.
  • Such an amplifier is particularly useful in high frequency circuits since it is capable of easy constructicn and accurate adjustment. It is clear that the desired and necessary connection of the load to the proper points on the loop and the proper impedance load may be readily chosen to adapt the system to any circuit in which it is desired to use this type of repeater connection.
  • FIG. 4A An adaptation of the loop repeater circuit of Fig. 4 to a radio repeater is illustrated in Fig. 4A,
  • antenna 240 is mounted at a suitably isolated location so that its field is substantially free from disturbing foreign obj ects, the retransmission may be made at the same frequency as the reception without creating any difficulties.
  • changes and movements about the antenna in the vicinity thereof may produce an unbalance in the bridge and a consequent feedback to amplifier 200 which produces undesirable howling and distortion.
  • the amplifier 200 may incorporate therein a frequency changer so that the frequency retransmitted differs from the .frequency received by a fixed amount, preferably above audibility.
  • the amplifier 208 then will serve to prevent this undesirable feedback through the proper construction and tuning of the circuit.
  • the frequency difference between the signals received and transmitted need not be. large, and may be such that both signals may be ordinariily received and detected on the same receiver.
  • the radio repeater circuit illustrated in Fig. 4A is particularly useful where coverage of territory around a fixed reception point with broadcast signals is desired.
  • the amplifier 200 may be so sensitive as to readily receive rather feeble signals and retransmit these signals at a substantially increased energy level for more ready general reception by less sensitive receiving sets.
  • FIG. 5 shows two such bridge circuits used in a two-way high frequency communication system.
  • a transmitter indicated at 30i is coupled over a bridge circuit shown generally at 303, through a transmission line 305, a second bridge circuit shown generally at 301, and a transmission line 309 to a receiver 3! i.
  • a receiver 40l is coupled to bridge circuit 303 at the voltage nodal point of the loop bridge. Accordingly, signals transmitted from 30! cannot interfere with the reception at 40!.
  • An impedance M3 is bridged across loop circuit 303 at a point spaced from the voltage nodal point a distance equal to the distance from said nodal point to the junction of line 305 with said bridge circuit.
  • the impedance element M3 is made equal in every respect to the impedance of the circuit coupled through line 305 to the bridge.
  • a transmitter MI is coupled across the voltage nodal points of loop bridge30'l, and an impedance balancing'unit 3l5 is provided across loop bridge 301, said impedance being equal to the load connected across the transmission line 305, and spaced a distance from the voltage nodal points position as shown in of the loop bridge circuit equal to the spacing of line 305 therefrom.
  • the compensating devices used to compensate for the reflection at the transposition point as illustrated in Figs. 2-5 may be omitted in many cases since the reflection due to transposition is normally rather small and may be compensated only be used when extremely fine adjustment of the loop is desired.
  • a half wavelength of the frequency being used may be inserted in one arm of the bridge as shown in Fig. 6.
  • a section of transmission line indicated shown-inserted in one side at 5, 5' and 6, 6' is of a bridge loop circuit similar to that shown in Fig. 1.
  • the voltage nodal point will occur at a different point in the bridge as indicated at I, 1'.
  • the operation of this bridge circuit is substantially identical with that shown in the other figures. -However, in this case the load impedances will be inserted at points spaced from the points 1, I, which are not at the apex of the loop, since the added half wavelength has been inserted in lieu" of the transposition.
  • the loop bridge circuit may likewise be constructed with any desired form of phase shifting unit used in place of the transposition.
  • Fig. '7 illustrates a system in which a phase shifter shown generally at 4 is inserted in one side of the loop. This phase shifter may be of any form but should be made so as to produce a 180 phase shift at the-desired working frequency.
  • the loop circuit has been shown as comprising simple wire lines, it is to be understood that any desired type of line may be used in this system.
  • the loop may be made of concentric cable conductors, or of insulated twisted pairs, or any desired known type of structure.
  • the operation of the system does not require that the loop be of some particular shape since any reflections caused by any sharp angles or irregularities in the line may be compensated for by other means inserted in the loop.
  • the loops may be constructed so as to include a part of a normal transmission line already in use, for a portion of their length, as suggested in my prior application, Serial No. 118,866, referred to above.
  • a conjugate bridge circuit comprising a reentrant loop circuit, means coupled to said loop at a first'point, other means coupled at a point on said loop substantially 180 different in distance electrically in opposite directions from the coupling point of said first named means, and substantially equal impedance means coupled to said loop on opposite sides of said second named point and at equal distances therefrom.
  • said first named means comprises a high frequency transmitting means
  • said second named means comprises a high frequency receiving means
  • said impedance means comprises a transmission line circuit and a matching impedance, respectively.
  • said first named means comprises the output of an amplifier.
  • said second named means comprises the input of an amplifier, and said impedance means'comprises a transmission line circuit and a matching impedance, respectively.
  • said first named means comprises the output circuit of a radio frequency amplifier
  • said second named means comprises the input circuit of said amplifier
  • said impedances comprise a transmission line coupled to a radio antenna and a matching impedance, respectively.
  • a high frequency communication system comprising a high frequency transmitter, a reentrant loop circuit coupled to said transmitter, a receiver coupled to said reentrant loop circuit at a point spaced equal electrical distances from said transmitter, a second reentrant loop circuit,
  • a second transmitter and receiver coupled to said secondloop circuit in conjugate relationship, a transmission line coupled to both said reentrant loop circuits at points on the loops between said receiver and transmitter, and balancing networks coupled to each reentrant loop circuit at points located symmetrically with respect to said transmission line coupling point.
  • a high frequency communication system comprising a pair of reentrant loop circuits, high frequency apparatus coupled to each of said reentrant loop circuits at conjugate points thereon, a transmission line connected to said reentrant loop circuits at points between said coupled apparatus, and balancing networks coupledto said loop circuits at points on the loop circuit symmetrically arranged with respect "to the connection point of said transmission line.
  • a high frequency bridge circuit comprising a high frequency source, a reentrant loop circuit coupled to said source, apparatus coupled to said loop circuit at a point equi-distant electrically from said transmission source, and means for establishing a voltage node at the point of connection of said apparatus, by introducing a phase shift of 180 in one arm of said loop.
  • a high frequency circuit according to claim 8 further comprising two substantially equal impedance means coupled to said reentrant loop circuits at points arranged symmetrically with respect to said apparatus couplingpoint.
  • a repeater circuit comprising an amplifier having an input and an output, a reentrant loop circuit, means to couple said amplifier at substantially conjugate points on said loop, a transmission line for transmitting signal energy, means for coupling said transmission line to a point on said loop intermediate said amplifier connections whereby energy may be conducted to and conducted from said amplifier, and means cooperating with the opposite side of said loop from that to which the transmission line is coupled, for maintaining the conjugate relation of said circuit.
  • a high frequency bridge circuit comprising high frequency apparatus, a reentrant loop circuit coupled to said apparatus, means coupled to said loop circuit at a point such that the two arms of said loop circuit between said point and the junction point of said loop circuit with said apparatus present equal electrical lengths, a load coupled to said bridge circuit at a distance from said means coupling point to provide for maximum energy transfer from said bridge, and a second means spaced at a distance equal said first named distance and on the opposite side of said coupling point, said second means presenting an impedance substantially equal to that of said lead.
  • a bridge circuit comprising a source of high frequency energy, a reentrant loop circuit coupled to said source so as to produce a voltage nodal point in said loop circuit, a load circuit coupled to said loop at a distance from said voltage nodal point, and means presenting substantially the same impedance as said load coupled'to said loop at a distance equal to that of the load from said voltage nodal point and on the opposite side of said voltage nodal point.
  • a high frequency bridge comprising a reentrant loop, means coupled to said loop to in troduce energy therein, said loop being so constructed that energy introduced therein produces a definite node at a point in said loop, means for coupling a load to said loop intermediate said first .named means and said nodal point, and means v arc-moo in said loop on the other side of said nodal point to compensate for said load and maintain the nodal point in its initial position.
  • a high frequency repeater comprising a reentrant bridge arrangement, means for coupling a repeating means to said bridge, the input of said repeating means being connected to a point on the bridge which is at a voltage node with respect to the output oi said repeating means, and means coupled to said bridge be,- tween said voltage nodal point and the output .of said repeating means, for introducing energy to the input of said repeating means and receiving the repeated energy from the output of said repeating means.
  • a repeater as claimed in claim 16 further comprising means in said loop circuit on the side of said voltage nodal point opposite said coupled means, for compensating for said coupled means to maintain the loop in stable condition.
  • a bridge circuit comprising energy supply means, means associated with said energy supply means for transmitting energy therefrom in two paths to a common point, said two paths being so proportioned that a voltage node is produced at said common point, a load circuit coupled to one of said paths at a distance from said common point and means presenting sub.- stantially the same impedance as said load coupled to the other of said paths at a corresponding distance from said common point.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
US140594A 1937-01-02 1937-05-04 High frequency bridge circuits and high frequency repeaters Expired - Lifetime US2147809A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
NL63339D NL63339C (de) 1937-05-04
US140594A US2147809A (en) 1937-05-04 1937-05-04 High frequency bridge circuits and high frequency repeaters
DEI3363D DE920730C (de) 1937-01-02 1938-01-04 Entkoppelnde Hochfrequenzbrueckenschaltung

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416105A (en) * 1943-09-30 1947-02-18 Rca Corp Transmit-receive switch
US2416790A (en) * 1941-01-28 1947-03-04 Sperry Gyroscope Co Inc Transmission line bridge circuit
US2436828A (en) * 1942-12-31 1948-03-02 Bell Telephone Labor Inc Coupling arrangement for use in wave transmission systems
US2485773A (en) * 1943-06-01 1949-10-25 Hartford Nat Bank & Trust Co Device for the alternating voltage supply of a load
US2507915A (en) * 1946-08-28 1950-05-16 Rca Corp Coupling circuit
US2534624A (en) * 1943-05-29 1950-12-19 Hartford Nat Bank & Trust Co Transmitting device
US2544832A (en) * 1945-08-08 1951-03-13 Jr Lawrence N Hadley Variable frequency tank circuit
US2639325A (en) * 1950-03-24 1953-05-19 Bell Telephone Labor Inc Hybrid ring
US2644928A (en) * 1948-06-09 1953-07-07 Rca Corp Directional transmission line transducer
US2666132A (en) * 1941-01-28 1954-01-12 Wilmer L Barrow Ultrahigh-frequency bridge circuit and apparatus
US2725533A (en) * 1941-01-28 1955-11-29 Wilmer L Barrow Bridge circuit embodying artificial transmission lines
US2765444A (en) * 1950-06-02 1956-10-02 Marconi Wireless Telegraph Co High frequency circuit arrangements
US2784381A (en) * 1948-10-05 1957-03-05 Bell Telephone Labor Inc Hybrid ring coupling arrangements
US3096493A (en) * 1959-07-23 1963-07-02 Gen Electric Co Ltd Four-terminal electric networks
DE976983C (de) * 1942-12-31 1964-10-15 Western Electric Co Kopplungseinrichtung fuer Wellenuebertragungssysteme
DE977019C (de) * 1942-12-31 1964-12-23 Western Electric Co Kopplungsanordnung fuer Wellenuebertragungssysteme
US3522526A (en) * 1967-03-17 1970-08-04 Albert E Sanderson Multiport radio frequency measuring and coupling circuits having matched input impedance at unknown port
US20100214177A1 (en) * 2009-02-26 2010-08-26 Harris Corporation, Corporation of the State of Delawre Wireless communications including an antenna for wireless power transmission and data communication and associated methods

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2416790A (en) * 1941-01-28 1947-03-04 Sperry Gyroscope Co Inc Transmission line bridge circuit
US2666132A (en) * 1941-01-28 1954-01-12 Wilmer L Barrow Ultrahigh-frequency bridge circuit and apparatus
US2725533A (en) * 1941-01-28 1955-11-29 Wilmer L Barrow Bridge circuit embodying artificial transmission lines
DE976983C (de) * 1942-12-31 1964-10-15 Western Electric Co Kopplungseinrichtung fuer Wellenuebertragungssysteme
US2436828A (en) * 1942-12-31 1948-03-02 Bell Telephone Labor Inc Coupling arrangement for use in wave transmission systems
DE977019C (de) * 1942-12-31 1964-12-23 Western Electric Co Kopplungsanordnung fuer Wellenuebertragungssysteme
US2534624A (en) * 1943-05-29 1950-12-19 Hartford Nat Bank & Trust Co Transmitting device
US2485773A (en) * 1943-06-01 1949-10-25 Hartford Nat Bank & Trust Co Device for the alternating voltage supply of a load
US2416105A (en) * 1943-09-30 1947-02-18 Rca Corp Transmit-receive switch
US2544832A (en) * 1945-08-08 1951-03-13 Jr Lawrence N Hadley Variable frequency tank circuit
US2507915A (en) * 1946-08-28 1950-05-16 Rca Corp Coupling circuit
US2644928A (en) * 1948-06-09 1953-07-07 Rca Corp Directional transmission line transducer
US2784381A (en) * 1948-10-05 1957-03-05 Bell Telephone Labor Inc Hybrid ring coupling arrangements
US2639325A (en) * 1950-03-24 1953-05-19 Bell Telephone Labor Inc Hybrid ring
US2765444A (en) * 1950-06-02 1956-10-02 Marconi Wireless Telegraph Co High frequency circuit arrangements
US3096493A (en) * 1959-07-23 1963-07-02 Gen Electric Co Ltd Four-terminal electric networks
US3522526A (en) * 1967-03-17 1970-08-04 Albert E Sanderson Multiport radio frequency measuring and coupling circuits having matched input impedance at unknown port
US20100214177A1 (en) * 2009-02-26 2010-08-26 Harris Corporation, Corporation of the State of Delawre Wireless communications including an antenna for wireless power transmission and data communication and associated methods
US8144066B2 (en) 2009-02-26 2012-03-27 Harris Corporation Wireless communications including an antenna for wireless power transmission and data communication and associated methods

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