US2501335A - Coaxial line to wave guide matching section - Google Patents

Coaxial line to wave guide matching section Download PDF

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Publication number
US2501335A
US2501335A US794148A US79414847A US2501335A US 2501335 A US2501335 A US 2501335A US 794148 A US794148 A US 794148A US 79414847 A US79414847 A US 79414847A US 2501335 A US2501335 A US 2501335A
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guide
wave guide
wave
coaxial
junction
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US794148A
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Lloyd P Hunter
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CBS Corp
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Westinghouse Electric Corp
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01PWAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
    • H01P5/00Coupling devices of the waveguide type
    • H01P5/08Coupling devices of the waveguide type for linking dissimilar lines or devices
    • H01P5/10Coupling devices of the waveguide type for linking dissimilar lines or devices for coupling balanced with unbalanced lines or devices
    • H01P5/103Hollow-waveguide/coaxial-line transitions

Definitions

  • My invention relates to junctions of coaxial cables towave-guides for transmitting ultra-highfrequency electromagnetic energy, and in particular relates to a novel disposition of the coaxial cable relative to. the wave guide to which connection ismade.
  • the characteristic impedance of the wave guide may be sufiiciently wellmatched to that of the coaxial cable by methods well known in the art, the arrangement is usually quite frequency sensitive so that if it is desired to transmit a fairly broad band of frequencies it is necessary to resort to alterations of the shape of the junction, such as the provision, of tuning devices which make the arrangement complicated" and difficult to manufacture. It is also frequently awkward from the standpoint of space limitations to be compelled to have the axis of the. coxial cable normal to the axis of the wave guide.
  • One object of my invention is accordingly: to provide-a novel way of connecting a coaxial cable to awave guide which shall avoid the awkward space limitation imposed by junctions of'the'prior art for such elements.
  • Another object of my invention is to provide a junction between a coaxial cable and a wave guide which is less sensitive to frequency variations of the electromagnetic energy being transmitted,
  • Still another object of my invention is to provide a new form of junction between a coaxial cable and a wave guide which shall have a relatively broad frequency acceptance while at the same time preserving a voltage standing wave ratio at least as good as those of junctions conventional in the prior art for such elements.
  • Still another object of my invention is to provide'a formof junction between a coaxial cable and awaveguide. which: shall be relatively insensitive to frequencyrvariations while; at the same time itis. easyto: manufacture andfree from the necessity for providing complicated adjustable tuning devices.
  • a wave guide- I- which: may have the rectangular crosssection which iswell known in the wave guide art, comprises parallel-conducting side wallslandlikewise a parallel conducting top and bottom wall.
  • Thewidth of this: guide may; for example, betwic'ethe height, although it" is to be understood. that my invention isnot limited to employment. with:-dimensi0ns. of this: particular ratio. While such a wave guide is capable of transmitting electromagnetic; energy in. a. number of different modes of? vibration which are well knownto'thoserskilled inthe art, I will; mention as an example of theseta: mode of vibration.
  • the wave guide 1 has a conducting end wall 2 perpendicular to its axis which is provided with acentral circula opening of the same size as the internal diameter of the sheath 3 of a concentric line supplying energy to the guide.
  • the sheath 3 makes a tight abutment with the end wall 2.
  • the central core 4 of the concentric line extends in substantial coincidence with the cen tral axis of the guide I into the interior of the latter for some distance and then turns at right angles in the plane of the electric vector to make contact with the face of the guide.
  • I once used a rectangular wave guide having a width of 2.84" and a height of 1.34", inside dimensions, and made of copper which was connected as I have described above to a coaxial line having a sheath of brass which is 1 /32 inches in inside diameter and a core of brass of A; of an inch diameter.
  • the system When transmitting in the above mentioned TEu,1 mode of vibration electromagnetic Waves having an open-air wave length of 10.6 cm., the system was operated over a range of frequency and I found that the standing wave ratio in the wave guide remained between 1.1 and 1.0 for a 5% change in frequency, while the standing Wave ratio in the coaxial line remained within the limits 1.03 and 1.00.
  • the core of the coaxial line in these tests projected 3.25 inches into the wave guide from the end wall 2, and the diaphragm 5, which was 8.76 inches from the end of the guide I, extended from top to bottom of the guide adjacent one wall and had a width of 0.437 of an inch.
  • a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length of the waves traversing said coaxial line and being connected with a side wall of said wave guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
  • a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end Wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length corresponding to a mode of Wave vibration which said guide is capable of transmitting, and making contact with a side wall of said guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
  • a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length corresponding to the TEc,1 mode of transmission of said guide and making junction with a side wall of said guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
  • a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, its central core extending into said guide for a distance about equal to one-half wave length corresponding to the TEn,1 mode of transmission of said wave guide and making junction with a side wall of said Wave guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line, and an inductive diaphragm in said wave guide beyond its junction with said core.
  • a coaxial line having one end of its sheath joined to said end wall of said guide, and having its core extending through said end wall parallel to the central axis of said wave guide and extending beyond said end wall for a distance about equal to a half-wave length of the TEUJ mode of transmission of waves through said guide and turning parallel to the electric vector of said waves and making juncture with a Wall of said guide whereb the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line, and an inductive diaphragm means in said wave guide beyond the said juncture.

Description

March 21, 1950 L. P. HUNTER 2,501,335
COAXIAL LINE T0 WAVE GUIDE MATCHING SECTION Filed Dec. 27, 1947 INVEN'fOR Lloyd P.Hunter.
ATTORN Patented Mar. 21., 1950 CSAXIAL LINE T WAVE MATCHING SECTION Lloyd 1?. Hunter, Qak Ridge, Tenn.,. assignor to.
Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania AppiicationDecember 27, 1 947,.SerialaNo; 794,148:
5 Claims ((31; 178-44) My invention relates to junctions of coaxial cables towave-guides for transmitting ultra-highfrequency electromagnetic energy, and in particular relates to a novel disposition of the coaxial cable relative to. the wave guide to which connection ismade.
It has been conventional in the prior art to effect a junction between a coaxial cable carrying ultraehigh-frequency electromagnetic energy and awave guide through: which the energy is to flow by arranging the axis of the coaxial cablenormal to thecentral axis of thewave guide at the junction, the end of the-wave guide near the junction being closed by a conducting wall, and the central, core. of the wave guide usually being. positioned. in the. neighborhood of a quarter wave length distant from. this partition. The axis ofthe coaxial cable is conventionally normal: to the surface of. the wave guide atits point: of entry; where the wave guide is a rectangular cross section, the coaxial cable passes through the middle ofone wall of the guide.
I- have found that while, insuch conventional. junctions, the characteristic impedance of the wave guide may be sufiiciently wellmatched to that of the coaxial cable by methods well known in the art, the arrangement is usually quite frequency sensitive so that if it is desired to transmit a fairly broad band of frequencies it is necessary to resort to alterations of the shape of the junction, such as the provision, of tuning devices which make the arrangement complicated" and difficult to manufacture. It is also frequently awkward from the standpoint of space limitations to be compelled to have the axis of the. coxial cable normal to the axis of the wave guide.
One object of my invention is accordingly: to provide-a novel way of connecting a coaxial cable to awave guide which shall avoid the awkward space limitation imposed by junctions of'the'prior art for such elements.
Another object of my invention is to provide a junction between a coaxial cable and a wave guide which is less sensitive to frequency variations of the electromagnetic energy being transmitted,
through them than were junctions of the prior art.
Still another object of my invention is to provide a new form of junction between a coaxial cable and a wave guide which shall have a relatively broad frequency acceptance while at the same time preserving a voltage standing wave ratio at least as good as those of junctions conventional in the prior art for such elements.
Still another object of my invention is to pro- 2 vide a-novel type of; junction between a coaxial cable and a wave guidewhich shall be of simple formand. easy manufacture while at the same time preserving a transmission efiiciency equal to'junctions between such elements of the prior art type. I
Still another object of my invention is to provide'a formof junction between a coaxial cable and awaveguide. which: shall be relatively insensitive to frequencyrvariations while; at the same time itis. easyto: manufacture andfree from the necessity for providing complicated adjustable tuning devices.
Other objects of my invention will become; apparent upon reading the following description; taken in connection withv the drawings, inwhich the single-figure showsan embodiment of my invention suitable for joining a" coaxial cable. of circular section with a wave guide ofrectangular section. 7
Referring, in detail to the drawings, a wave guide- I- which: may have the rectangular crosssection which iswell known in the wave guide art, comprises parallel-conducting side wallslandlikewise a parallel conducting top and bottom wall. Thewidth of this: guide may; for example, betwic'ethe height, although it" is to be understood. that my invention isnot limited to employment. with:-dimensi0ns. of this: particular ratio. While such a wave guide is capable of transmitting electromagnetic; energy in. a. number of different modes of? vibration which are well knownto'thoserskilled inthe art, I will; mention as an example of theseta: mode of vibration. in which the electriavectors extendverti'cally between the topandbottom'wallsand varysinusoidall'y in density distribution, both parallel to the axis of theguideand'zinisther direction transverse to'the guide. Such: a. mode: of vibration is som'etimes referred toiasa'a-TEartyp'e ofwave transmission.
The wave guide 1 has a conducting end wall 2 perpendicular to its axis which is provided with acentral circula opening of the same size as the internal diameter of the sheath 3 of a concentric line supplying energy to the guide. The sheath 3 makes a tight abutment with the end wall 2. The central core 4 of the concentric line extends in substantial coincidence with the cen tral axis of the guide I into the interior of the latter for some distance and then turns at right angles in the plane of the electric vector to make contact with the face of the guide. I have found that a good match between the impedance of the concentric line and the guide results if the distance between the above mentioned point of attachment of the core to the guide wall from the end wall 2 is about one-half of the wave length of the electromagnetic energy being transmitted. I have likewise found it desirable for many purposes to provide a diaphragm extending part way across the guide I at a short distance beyond the end of the core 4 of the coaxial line, this diaphragm 5 being one form of inductive diaphragm which may be proportioned to match out any small irregularities and reflections introduced into the transmitted waves by the junction of the coaxial line and the wave guide. Other types of inductive diaphragm may be employed for this purpose where desirable.
To give a specific example, I once used a rectangular wave guide having a width of 2.84" and a height of 1.34", inside dimensions, and made of copper which was connected as I have described above to a coaxial line having a sheath of brass which is 1 /32 inches in inside diameter and a core of brass of A; of an inch diameter. When transmitting in the above mentioned TEu,1 mode of vibration electromagnetic Waves having an open-air wave length of 10.6 cm., the system was operated over a range of frequency and I found that the standing wave ratio in the wave guide remained between 1.1 and 1.0 for a 5% change in frequency, while the standing Wave ratio in the coaxial line remained within the limits 1.03 and 1.00. The core of the coaxial line in these tests projected 3.25 inches into the wave guide from the end wall 2, and the diaphragm 5, which was 8.76 inches from the end of the guide I, extended from top to bottom of the guide adjacent one wall and had a width of 0.437 of an inch.
I claim as my invention:
1. In an electromagnetic wave transmitting system, a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length of the waves traversing said coaxial line and being connected with a side wall of said wave guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
2. In combination, a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end Wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length corresponding to a mode of Wave vibration which said guide is capable of transmitting, and making contact with a side wall of said guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
3. In combination, a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, and its central core extending into said guide for a distance about equal to one-half wave length corresponding to the TEc,1 mode of transmission of said guide and making junction with a side wall of said guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line.
4. In combination, a rectangular wave guide having an end wall and a coaxial transmission line joining said wave guide with its central core parallel to the central axis of the wave guide at their junction, one end of its sheath being in abutment with said end wall of said guide, its central core extending into said guide for a distance about equal to one-half wave length corresponding to the TEn,1 mode of transmission of said wave guide and making junction with a side wall of said Wave guide whereby the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line, and an inductive diaphragm in said wave guide beyond its junction with said core.
5. In combination with a rectangular wave guide having a transverse end wall, a coaxial line having one end of its sheath joined to said end wall of said guide, and having its core extending through said end wall parallel to the central axis of said wave guide and extending beyond said end wall for a distance about equal to a half-wave length of the TEUJ mode of transmission of waves through said guide and turning parallel to the electric vector of said waves and making juncture with a Wall of said guide whereb the impedance of said wave guide is substantially matched to the impedance of said coaxial transmission line, and an inductive diaphragm means in said wave guide beyond the said juncture.
LLOYD P. HUNTER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 2,151,118 King Mar. 21, 1939 2,232,179 King Feb. 18, 1941 2,316,151 Barrow Apr. 13, 1943 2,398,095 Katzin Apr. 9, 1946 2,432,093 Fox Dec. 9, 1947
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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627551A (en) * 1948-12-15 1953-02-03 Gen Electric Ultrahigh-frequency transmission structure
US2654868A (en) * 1951-09-20 1953-10-06 Gen Precision Lab Inc Microwave rotatable joint
US2686902A (en) * 1950-07-24 1954-08-17 Bell Telephone Labor Inc Microwave branching arrangement
US2742612A (en) * 1950-10-24 1956-04-17 Sperry Rand Corp Mode transformer
US2930008A (en) * 1955-07-07 1960-03-22 Gen Electric Co Ltd Waveguide arrangements including windows for passing electromagnetic waves
US3483489A (en) * 1968-01-31 1969-12-09 Bell Telephone Labor Inc End launch stripline-waveguide transducer
US3758886A (en) * 1972-11-01 1973-09-11 Us Navy Versatile in line waveguide to coax transistion
US3942138A (en) * 1974-02-04 1976-03-02 The United States Of America As Represented By The Secretary Of The Air Force Short depth hardened waveguide launcher assembly element

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2151118A (en) * 1935-10-30 1939-03-21 Bell Telephone Labor Inc Termination for dielectric guides
US2232179A (en) * 1938-02-05 1941-02-18 Bell Telephone Labor Inc Transmission of guided waves
US2316151A (en) * 1939-01-09 1943-04-13 Research Corp Electromagnetic horn
US2398095A (en) * 1940-08-31 1946-04-09 Rca Corp Electromagnetic horn radiator
US2432093A (en) * 1942-07-30 1947-12-09 Bell Telephone Labor Inc Wave transmission network

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2151118A (en) * 1935-10-30 1939-03-21 Bell Telephone Labor Inc Termination for dielectric guides
US2232179A (en) * 1938-02-05 1941-02-18 Bell Telephone Labor Inc Transmission of guided waves
US2316151A (en) * 1939-01-09 1943-04-13 Research Corp Electromagnetic horn
US2398095A (en) * 1940-08-31 1946-04-09 Rca Corp Electromagnetic horn radiator
US2432093A (en) * 1942-07-30 1947-12-09 Bell Telephone Labor Inc Wave transmission network

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2627551A (en) * 1948-12-15 1953-02-03 Gen Electric Ultrahigh-frequency transmission structure
US2686902A (en) * 1950-07-24 1954-08-17 Bell Telephone Labor Inc Microwave branching arrangement
US2742612A (en) * 1950-10-24 1956-04-17 Sperry Rand Corp Mode transformer
US2654868A (en) * 1951-09-20 1953-10-06 Gen Precision Lab Inc Microwave rotatable joint
US2930008A (en) * 1955-07-07 1960-03-22 Gen Electric Co Ltd Waveguide arrangements including windows for passing electromagnetic waves
US3483489A (en) * 1968-01-31 1969-12-09 Bell Telephone Labor Inc End launch stripline-waveguide transducer
US3758886A (en) * 1972-11-01 1973-09-11 Us Navy Versatile in line waveguide to coax transistion
US3942138A (en) * 1974-02-04 1976-03-02 The United States Of America As Represented By The Secretary Of The Air Force Short depth hardened waveguide launcher assembly element

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