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Publication numberUS3453574 A
Publication typeGrant
Publication dateJul 1, 1969
Filing dateMar 22, 1968
Priority dateMar 22, 1968
Publication numberUS 3453574 A, US 3453574A, US-A-3453574, US3453574 A, US3453574A
InventorsParry Theodore De
Original AssigneeAtomic Energy Commission
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
High-frequency,wide-band transformer
US 3453574 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

y 1, 1969 T. DE PARRY 3,453,574

HIGH-FREQENCL WIDE-BAND TRANSFORMER Filed March 22, 1968 Sheet 0 1 2 In 2/8 to) Theodore de Pa/gy July 1, 1969 T. DE PARRY 3,453,574

HIGH-FREQENCY WIDE-BAND TRANSFORMER Filed March 22, 1968 Sheet 2 of 2 .5 5mm. C o f? 2 D GENER/YTOR 1g 4% v 6 12 6 Moms 5 M T 1/ w v y FREQUENCY (Me/5) F 5- 4 In zfeflor 2726040119 46 Par 1y United States Patent Oflice U.S. Cl. 336-182 1 Claim ABSTRACT OF THE DISCLOSURE Contractual origin of the invention The invention described herein was made in the course of, or under, a contract with the United States Atomic Energy Commission.

Background of the invention This invention relates to transformers and more particularly to high-frequency, wide-band transformers having a high turns ratio.

High-frequency, wide-band transformers enjoy a wide usage in the electrical art. For example, application therefor. is found in the radiofrequency section of particle accelerators. It is difficult, using the present state of the art, to obtain a high-frequency, wide-band transformer having a high turns ratio, a high coupling coefficient and a flat broad-band response. When the turns ratio is above 2 to 1, it is difiicult to obtain efficient coupling in the standard high-frequency transformer. Further, flat broadband frequency response is not readily available in transformers having high turns ratios.

Accordingly, it is one object of the present invention to provide an improved high-frequency, wide-band transformer.

It is another object of the a high-frequency, turns ratio.

It is another object of the present invention to provide a high-frequency, wide-band transformer having a high coupling coefiicient between the windings thereof.

It is another object of the present invention to provide a high-frequency, wide-band transformer having minimal stray inductance loss.

It is another object of the present invention to provide a high-frequency, wide-band transformer having a flat response and a turns ratio in excess of 2 to 1.

Other objects of the present invention will become more apparent as the detailed description proceeds.

present invention to provide wide-band transformer having a high Summary of the invention In general, the transformer of the present invention comprises core means and a cable wound about said core means including an inner conductor and an outer conductor surrounding the inner conductor. The outer conductor of the cable is sectionally discontinuous. Means are provided for electrically interconnecting each of the 3,453,574 Patented July 1, 1969 outer conductor sections. The inner and outer conductors each form a winding of the transformer.

Brief description of the drawings Further understanding of the present invention may best be obtained from consideration of the accompanying drawings wherein:

FIG. 1 is a diagram of a transformer constructed according to the present invention.

FIG. 2 is a drawing of the transformer of FIG. I having a different turns ratio connection.

FIG. 3 is a schematic of a transformer constructed according to the present invention together with the testing circuit therefor.

FIG. 4 is a graphical representation of the characteristics obtained with the transformer of FIG. 3.

Description of the preferred embodiment In FIG. 1, a coaxial cable 10 comprising an inner conductor 12 and an outer conductor 14 is helically wound about a ferrite toroidal core 16. The inner conductor 12 comprises the primary winding of the transformer having input terminals 18 and 20. The outer conductor 14 comprises the secondary winding of the transformer with output terminals 22 and 24. The transformer of FIG. 1 is shown in a center-tap push-pull configuration having a 4 to 1 step down turns ratio. To obtain this structure, the outer conductor 14 is made sectionally discontinuous and the leading and lagging ends (a and b) of the sections 26 through 40 in each half of the transformer are connected as shown so that the secondary winding is electrically equivalent to a single turn of a conductor about a magnetic core wound with four primary turns. It is to be noted that, though the aforedescribed example illustrates a center-tap push-pull transformer configuration, the present invention is not to be limited thereto, nor is the structure limited to a toroidal core configuration. Other core shapes (such as rectangular and H- shaped cores) and other winding configurations may be substituted therefor. Further, it will be appreciated that turns ratios other than that illustrated are obtainable according to the present invention by different interconnection of the sections of the outer conductor 14. For example, a turns ratio of 2 to 1 may "be obtained with the transformer of FIG. 1 by interconnecting the leading and lagging ends (26b to 28a, 30b to 32a, 34a to 36b, 38a to 40b) of the sections of outer conductor 14, as shown in FIG. 2.

Turning to FIG. 3, a schematic equivalent is shown for the transformer of FIG. 1. The transformer 42 was constructed according to the structure of the transformer of FIG. 1 in a push-pull center-tap configuration and a 3 to 1 turns ratio (6 turn primary, 2 turn equivalent sec ondary). A signal generator 44 provided a constantamplitude signal at a frequency variable bet-ween kilohertz and 50 megahertz. This signal was applied across the primary winding 46 of transformer 42. The output voltage from the secondary Winding 48 of transformer 42 was measured and recorded by recorder 50. The results obtained with the transformer 42 of FIG. 3 are shown in the graphical plot of FIG. 4. The curve 52 represents the input voltage applied to the primary winding 46 and the curve 54 represents the output voltage from the secondary winding 48. The voltage applied to the primary winding 46, as stated, was maintained at a constant amplitude (6 volts) throughout the frequency spectrum tested. It is to be noted that the transformer 42 exhibited a completely flat response to 10 megacycles and only a 30% deviation therefrom between 10 megacycles and 19 megacycles. The specific performance data of the transformer 42 indicated that the coupling coefiicient between the primary and secondary windings 46 and 48 approached 1 and that stray inductance loss was lowered by the configuration-of the transformer. It is to be noted that the amount of coupling and/or stray inductance loss may be varied as a function of the diameters of the two conductors forming the cable 10. Similar results were obtained with the windings 46 and 48 of transformer 42 having turns ratios of 6 to 1 and 10 to 1.

Though the foregoing examples have indicated that the cable 10 from which the transformer is constructed is of a coaxial construction, it is to be understood that for the practice of the present invention it is only necessary that an inner conductor be used which is completely surrounded by an outer conductonThus, rectangular conductors may be used provided one is inserted within the other.

Persons skilled in the art will, of course, readily adapt the general teachings of the invention to embodiments far different from the embodiments illustrated. Accordingly, the scope of the protection afforded the invention should not be limited to the particular embodiment illustrated in the drawings and described above, but should be determined only in accordance -with the appended claim.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A transformer comprising a toroidal core, first and second like coaxial cables each spirally wound in the same directional sense around the periphery of an associated portion of said toroidal core, the outer conductors of said coaxial cables being sectionally discontinuous, the inner and outer conductors of said coaxial cables each forming windings of said transformer, means for electrically grounding one pair of adjacent ends of the inner conductors of said coaxial cables, the other pair of 'adjacent ends of the inner conductors of said coaxial cables being terminals to the transformer windings formed thereby, means for electrically grounding one pair of adjacent ends of the outer conductors of said coaxial cables, and alternate related ends therefrom of said discontinuous sections of said outer conductors, the other pair of adjacent ends of the outer conductors of said coaxial cables being terminals to the transformer windings formed thereby, and means for connecting to an associated one of said other pair of adjacent ends of said outer conductors alternate related ends therefrom of said discontinuous sections of said outer conductor.

References Cited UNITED STATES PATENTS 1,827,191 10/1931 Casper 336 XR 2,348,325 5/1944 'Brown 336-195 XR 3,005,965 10/1961 Wertanen 336-195 XR 3,066,266 11/1962 Fisher 336229 XR 3,195,076 7/1965 Morrison 336181 XR 3,260,977 7/ 1966 Coltman 336-l81 FOREIGN PATENTS 867,044 4/ 1961 Great Britain.

LEWIS H. MYERS, Primary Examiner.

T. J. KOZMA, Assistant Examiner.

US. Cl. X.R. 336195, 229

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1827191 *Jun 6, 1930Oct 13, 1931Bell Telephone Labor IncShielded inductance
US2348325 *Apr 26, 1941May 9, 1944Rca CorpElectrical transformer
US3005965 *Feb 8, 1956Oct 24, 1961Wertanen Urho LElectrical impedance devices
US3066266 *Mar 17, 1959Nov 27, 1962Fisher Alan JRadio frequency transformer
US3195076 *Jul 7, 1961Jul 13, 1965Westinghouse Electric CorpImpedance matching balun employing a ferrite core
US3260977 *Jul 2, 1964Jul 12, 1966Westinghouse Electric CorpElectrical apparatus
GB867044A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3675176 *May 12, 1971Jul 4, 1972Racal Mobilcal LtdElectrical transformers
US3702453 *Jul 19, 1971Nov 7, 1972Atomic Energy CommissionTemperature-compensated trimming windings for water-cooled magnet coils
US4777466 *Apr 18, 1986Oct 11, 1988Senter For IndustriforskningConnector arrangement for electrical circuits in underwater installations, and transformer particularly for use in such arrangement
US4806896 *Jul 13, 1988Feb 21, 1989Mitsubishi Denki Kabushiki KaishaElectromagnetic shield for electromagnetic apparatus
US5130678 *Oct 31, 1991Jul 14, 1992Rockwell International CorporationTransmission line transformer with DC isolation
US5301096 *Oct 20, 1992Apr 5, 1994Electric Power Research InstituteSubmersible contactless power delivery system
US5341083 *Oct 20, 1992Aug 23, 1994Electric Power Research Institute, Inc.Contactless battery charging system
US5705971 *Jul 26, 1996Jan 6, 1998Allen-Bradley Company, Inc.Low leakage coaxial transformers
US7009486 *Sep 18, 2003Mar 7, 2006Keithley Instruments, Inc.Low noise power transformer
US7821374 *Jan 4, 2008Oct 26, 2010Keyeye CommunicationsWideband planar transformer
US8203418Dec 1, 2009Jun 19, 2012Planarmag, Inc.Manufacture and use of planar embedded magnetics as discrete components and in integrated connectors
US20090002111 *Jan 4, 2008Jan 1, 2009William Lee HarrisonWideband planar transformer
US20100295646 *Dec 1, 2009Nov 25, 2010William Lee HarrisonManufacture and use of planar embedded magnetics as discrete components and in integrated connectors
EP0932168A2 *Jan 25, 1999Jul 28, 1999ABB Daimler-Benz Transportation (Technology) GmbHCoaxial transformer
EP0932168A3 *Jan 25, 1999May 31, 2000ABB Daimler-Benz Transportation (Technology) GmbHCoaxial transformer
Classifications
U.S. Classification336/182, 336/195, 336/229
International ClassificationH01F27/28
Cooperative ClassificationH01F27/288
European ClassificationH01F27/28G