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Publication numberUS3904991 A
Publication typeGrant
Publication dateSep 9, 1975
Filing dateJan 31, 1974
Priority dateFeb 12, 1973
Publication numberUS 3904991 A, US 3904991A, US-A-3904991, US3904991 A, US3904991A
InventorsIshii Takimi, Nagai Torao, Suzuki Isao
Original AssigneeTokyo Shibaura Electric Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Stripline directional coupler having bent coupling arms
US 3904991 A
Abstract
A coupled line type directional coupler comprises a first directional coupling unit including mutually insulated first and second metal strip lines having a length of lambda /4 which are crossed three-dimensionally at the center of the directional coupling unit and run parallel to each other, the first and second metal strip lines being bent substantially at a right angle and substantially at the center of the first directional coupling unit; and a second directional coupling unit including mutually insulated third and fourth metal strip lines having a length of lambda /4 which are crossed three-dimensionally at the center of the directional coupling unit and run parallel to each other, the third and fourth strip lines being bent substantially at the center of the second directional coupling unit, whereby the first and second directional coupling units are directly coupled in tandem.
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United States Patent [191 Ishii et al.

[451 Sept. 9, 1975 STRIPLINE DIRECTIONAL COUPLER HAVING BENT COUPLING ARMS Inventors: Takimi Ishii, Yokohama; Isao Suzuki, Kawasaki; Torao Nagai, Yokohama, all of Japan Assignee: Tokyo Shibaura Electric Co., Ltd.,

Kawasaki, Japan Filed: Jan. 31, 1974 App]. No.: 438,404

Primary ExaminerPaul L. Gensler Attorney, Agent, or FirmOblon, Fisher, Spivak, McClelland & Maier [5 7] ABSTRACT A coupled line type directional coupler comprises a first directional coupling unit including mutually insulated first and second metal strip lines having a length of M4 which are crossed three-dimensionally at the center of the directional coupling unit and run parallel to each other, the first and second metal strip lines being bent substantially at a right angle and substantially at the center of the first directional coupling unit; and a second directional coupling unit including mutually insulated third and fourth metal strip lines having a length of M4 which are crossed threedimensionally at the center of the directional coupling unit and run parallel to each other, the third and fourth strip lines being bent substantially at the center of the second directional coupling unit, whereby the first and second directional coupling units are directly coupled in tandem.

2 Claims, 5 Drawing Figures [30] Foreign Application Priority Data Feb. 12, 1973 Japan 48-17212 [52] US. Cl. 333/10; 333/84 M [51] Int. Cl. I-lOlp 5/14 [58] Field of Search 333/10, 84 M [56] References Cited UNITED STATES PATENTS 3,167,727 1/1965 Lunden et al 333/l0 X 3,737,810 6/1973 Shelton 333/10 PORTI L PORT lll PATENTED 91975 3.904.991.

F I G. 1 PRIOR ART PORT 1 Y A PORT I11 PORT 11 1 1 PORT 1v PORT 1 v 1 PORT 111 F l G. 2

PORT H Y APORT EZ -FIG.3

3o PORTHI 1 PoFmV PATEHTED SEP 9 75 SHEET 2 BF 2 FIG. 4

PORT 1V PORT 111 FREQUENCY (GHZ 1 STRIPLINE DIRECTIONAL COUPLER HAVING BENT COUPLING ARMS This invention relates to a coupled line type directional coupler, particularly to a directional coupler for use in a microwave strip circuit.

A coupled line type directional coupler as shown in FIG. 1 has been used as a mixer in amicrowave receiving device. The coupled line type directional coupler is provided with directional coupling units 1, 2 coupled in tandem. The directional coupling unit I has a pair of strip lines 3, 4 having a length of M4 (A being the wavelength of the handled signal) which are crossed at the center of the directional coupling unit and run parallel to each other. The directional coupling units 1, 2 are coupled in tandem by means of strip lines 7, 8.

With the directional coupler, the strip lines 7, 8 are advantageously made longer so as to prevent a mutual influence of the directional coupling units 1, 2. However, when the strip lines 7, 8 are made longer, the strip lines 7, 8 per se impart an influence to the characteristics of the coupled line type directional coupler. Furthermore, a bulkier directional coupler results. Therefore, the length of the strip lines 7, 8 is empirically determined to be M4. FIG. 4 shows in broken lines output characteristics at a port II and VSWR at a port I involved when a signal of 2.0-4.0 GHz is applied to the port I. As will be evident from this figure, an amount of attenuation of an output at the port II is below 20 dB and VSWR is l.3l .4 which indicates a poor characteristic.

This invention relates to a small-sized directional coupler whose characteristics are improved.

In one aspect of this invention there is provided a directional coupling comprising a first directional coupling unit having mutually insulated first and second strip lines having a length of M4 which are crossed at one location and run parallel to each other, the first and second strip lines being bent, a second directional coupling unit having mutually insulated third and fourth strip lines having a length of M4 which are crossed at one location and run parallel to each other, the third and fourth strip lines being bent, whereby the first and second directional coupling units are directly coupled in tandem.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagrammatic view showing a conventional coupled line type directional coupler;

F IG. 2 is a diagrammatic view illustrating the principle of a coupled line type directional coupler according to this invention;

FIG. 3 is a perspective view of a directional coupler based on the principle of FIG. 2;

FIG. 4 is an explanatory view showing the characteristics of coupled line type directional couplers based on the principle of FIGS. 1 and 2; and

FIG. 5 is a diagrammatic view illustrating the principle of another coupled line type directional coupler according to this invention.

A coupled line type directional coupler shown in FIG. 2 is provided with directional coupling units ll, 12 having a degree of coupling of 8.34 dB. The directional coupling unit 1] has mutually insulated metal strip lines 13, 14 having a length of M4 which are threedimensionally crossed substantially at the central portion of the directional coupling unit and run parallel to each other at the remaining portion. The directional coupling unit 12 has mutually insulated metal strip lines 15, 16 having a length of N4 which are threedimensionally crossed substantially at the central portion of the directional coupling unit 12 and run parallel to each other at the remaining portion. The metal strip lines 13, 14 and l5, 16 are bent substantially at a right angle at the crossed central portion so that the respective both ends of the metal strip lines l3, 14 are arranged opposite to the respective both ends of the metal strip lines 15, 16. One end of the metal strip line 13 is coupled directly to one end of the metal strip line 16 which is opposite to the one end of the strip line 13 and one end of the metal strip line 14 corresponding to the other end of the strip line 13 is coupled directly to one end of the metal strip line 15 corresponding to the other end of the strip line 16 so that the directional coupling units 11 and 12 are coupled in tandem to provide a directional coupler. The respective other ends of the metal strip lines 13, l4, l5 and 16 are extended to form ports I, II, III and IV. The metal strip lines 14 and 16 have metal strips 17 and 18, respectively. The metal strip 17 spans the metal strip 13 at one location where the metal strip lines 13 and 14 are to be crossed relative to each other, while the metal strip 18 spans the metal strip 15 at one location where the metal strip lines 15 and 16 are to be crossed relative to each other.

The directional coupler has no coupling strip lines 7, 8 for the directional coupler shown in FIG. 1. This completely obviates disadvantages such as the bulkiness of a directional coupler, deterioration of directivity and VSWR, and so on. caused due to the presence of such coupling strip lines.

FIG. 3 shows one embodiment based on the principle of FIG. 2. A directional coupler of the type shown in FIG. 2 is formed on an alumina substrate 21. Sections corresponding to respective metal strips l3, l4, l5, 16 are formed on an alumina substrate 21 (dielectric constant 10.5) of a chromiumgold double layer having a 0.635 mm thickness. Gold strips 17 and 18 are used to span the strip lines 13 and 15, respectively. The width of each strip line is made to be 0.380 mm and a spacing between the strip lines 13 and 14 and a spacing between the strip lines 15 and 16 are made to be 0.110 mm, respectively. Respective ports I, II, III, IV are connected to coaxial plugs 22, 23, 24, 25 so as to be coupled to outer coaxial lines (not shown). The substrate 21 is secured to a metal block 30 by fitting means 26, 27, 28 and 29. In a graphical representation of FIG. 4 solid lines show output characteristics at the ports II, III and IV and VSWR at the port I involved when input signal is applied to the port I of the coupled line type directional coupler. An operating central frequency is 3 GHZ. As will be evident from this figure, an amount of attenuation at the outlet of the port II is improved up to more than 20 dB and VSWR is restricted to below 1.2.

Such improved characteristics are attained by directly coupling the directional coupling units 11 and 12 in tandem without interposing any strip lines such as coupling strip lines 7, 8 etc. as is found in a conventional direction coupler. Furthermore, it is possible to reduce the size of a directional coupler to a greater extent by bending the directional coupling unit as shown in FIG. 2.

With the above-mentioned embodiment the direc tional coupling units 11, 12 are bent at a right angle substantially at the center thereof. However, the directional coupling unit may be bent at an acute or obtuse angle. The directional coupling unit may be coupled in a semicircular shape as shown in FIG. 5. The metal strip lines l3, l4 and l5, 16 are crossed substantially at the respective center thereof. However, the crossed portions may be located at other than the center of the strip lines. Though with the above-mentioned embodiment two directional coupling units are coupled in tandem, a plurality of directional coupling units may be coupled in tandem.

What is claimed is:

l. A directional coupler comprising a first directional coupling unit including mutually insulated first and second strip lines having a length of )\/4 where A is the wavelength of the handled signal which are crossed at one portion and run parallel to each other at the remaining portion, the first and second strips being bent, a second directional coupling unit including mutually insulated third and fourth strip lines having a length of M4 which are crossed at one portion and run parallel to each other at the other portion, the third and fourth strip lines being bent so that the respective both ends of the first and second strip lines are opposite to the respective both ends of the third and fourth strip lines,

the first and second directional coupling units being directly coupled in tandem, the first and second lines being bent substantially at a right angle and crossed at the center thereof and the third and fourth strip lines being bent substantially at a right angle and crossed at the center thereof.

2. A directional coupler comprising a first directional coupling unit including mutually insulated first and second strip lines having a length of M4 where A is the wavelength of the handled signal which are crossed at one portion and run parallel to each other at the remaining portion, the first and second strips being bent, a second directional coupling unit including mutually insulated third and fourth strip lines having a length of M4 which are crossed at one portion and run parallel to each other at the other portion, the third and fourth strip lines being bent so that the respective both ends of the first and second strip lines are opposite to the respective both ends of the third and fourth strip lines, the first and second directional coupling units being directly coupled in tandem, the first and second strip lines being bent in a semi-circular shape and crossed at the center thereof and the third and fourth strip lines being bent in a semi-circular shape and crossed at the

Patent Citations
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US3167727 *Mar 9, 1961Jan 26, 1965Boeing CoMicrowave zig-zag line couplers
US3737810 *May 5, 1969Jun 5, 1973Radiation Systems IncWideband tem components
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3980972 *Jul 14, 1975Sep 14, 1976Stanford Research InstituteProximity coupler
US4011528 *Jul 14, 1975Mar 8, 1977Stanford Research InstituteSemi-lumped element coupler
US4127832 *Mar 28, 1977Nov 28, 1978Riblet Gordon PDirectional coupler
US4816784 *Jan 19, 1988Mar 28, 1989Northern Telecom LimitedBalanced planar transformers
US5262740 *Apr 9, 1992Nov 16, 1993Itt CorporationMicrostrip transformer apparatus
US5818307 *Mar 11, 1997Oct 6, 1998Motorola, Inc.Directional coupler having inductor crossing microstrip transmission line
US6972639Dec 8, 2003Dec 6, 2005Werlatone, Inc.Bi-level coupler
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US7132906Jun 25, 2003Nov 7, 2006Werlatone, Inc.Coupler having an uncoupled section
US7138887Feb 7, 2005Nov 21, 2006Werlatone, Inc.Coupler with lateral extension
US7190240Nov 17, 2005Mar 13, 2007Werlatone, Inc.Multi-section coupler assembly
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CN103367314A *Jun 19, 2013Oct 23, 2013日月光半导体制造股份有限公司半导体变压器
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Classifications
U.S. Classification333/116
International ClassificationH01P5/16, H01P5/18
Cooperative ClassificationH01P5/185
European ClassificationH01P5/18D1