JP2001111313A - Directional coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high directional coupler. SOLUTION: This high directional coupler is provided with at least first and second directional couplers 120 and 122 which respectively generate a forward signal and a backward signal from a signal propagating through a transmission line 100. A connector 124 connects the forward signals by an addition system and the backward signals so that they can cancel each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a directional coupler.

[0002]

2. Description of the Related Art FIG. 1 shows a conventional directional coupler. In the figure, a directional coupler 20 is formed near the transmission line 10. The arrows along the transmission line 10 indicate the transmission direction of the signal propagating along the transmission line 10. The directional coupler 20 combines the signals to produce a forward signal, but also produces a backward signal to combine the reflected portion of the signal. The reverse signal flows to the ground after passing through the resistor 24.

The directivity of the directional coupler 20 refers to the ratio of the forward signal power when a signal propagates in the transmission direction to the reverse signal power when the signal propagates in the transmission line 10 in the reverse direction. Thus, a 30 dB directional coupler having a 20 dB directivity generates a 30 dB forward signal from the signal on transmission line 10, and
A reverse signal of about 50 dB is generated from the above signal.

[0004]

A typical directional coupler as shown in FIG. 1 has a directivity of 15 dB to 30 dB. 45dB directivity by manufacturing with high accuracy
Can be increased up to. However, there is a need for a directional coupler that has high directivity without being manufactured with high precision.

[0005]

SUMMARY OF THE INVENTION The high directional coupler of the present invention combines the outputs of at least two directional couplers and combines the forward signals generated by each directional coupler in an additive manner, while each The reverse signal generated by the directional coupler is canceled (canceled).
As a result, a much higher directionality can be achieved than achieved with a single directional coupler, without requiring precise manufacturing.

[0006]

FIG. 2 shows a directional coupler according to one embodiment of the present invention. In the figure, a first directional coupler first and a second directional coupler 120 and 122 are connected to a transmission line 1.
It is formed close to 00. The manufacturing tolerances are different for the first and second directional couplers 120 and 12.
2 is the same. Furthermore, in one embodiment,
First directional coupler first and second directional couplers 120 and 1
Reference numeral 22 has the same structure and operates in the same manner as the directional coupler 20 as described in detail with reference to FIG.

The arrows along transmission line 100 indicate the direction in which the main signal propagates along transmission line 100. First directional coupler first and second directional coupler 120
And 122 are arranged in series at a predetermined distance along the transmission line 100 such that the forward signals generated by the first and second directional couplers 120 and 122 are: 270 degrees out of phase.

That is, assuming that the first forward signal generated by first directional coupler 120 has a reference phase of zero, the second forward signal generated by second directional coupler 122 has a 270 degree angle. It has a phase. Similarly, if the second backward signal generated by the second directional coupler 122 has a reference phase of zero, then the first directional coupler 120
Will have a 270 degree phase.

The first and second directional couplers 120 and 122 are connected to respective inputs of a 90-degree coupler 124. The 90 degree combiner 124 has a combined forward signal output 126 and a terminated combined reverse signal output 128. In generating the combined forward signal, combiner 124 rotates the phase of the second forward signal by 90 degrees, and then combines the first and second forward signals (i.e., -90 degrees). Coupler). Similarly, combiner 124 rotates the phase of the second backward signal by 90 degrees to combine the first and second backward signals.

When the second forward signal is rotated 90 degrees, the resulting phase for the first forward signal is 270 + 90 = 360 degrees. As a result, the first and second
Are in phase when combined. First
Directional coupler first and second directional couplers 120 and 122
Is a 30 dB coupler, combiner 124 is a 3 dB coupler with 20 dB cancellation, and the resulting combined forward signal is -27 dB relative to the main signal.

When the second reverse signal is rotated by 90 degrees,
The resulting phase is 0 + 90 = 90 degrees. As a result, the first and second forward signals are 180 degrees out of phase when combined (270 degrees and 90 degrees, respectively).
Every time). First directional coupler first and second directional couplers 12
If 0 and 122 are 30 dB couplers with 20 dB directivity, combiner 124 is a 3 dB coupler with 20 dB cancellation, and the resulting combined reverse signal is -70 dB. Therefore, the directivity of the directional coupler is 43 dB.

FIG. 3 shows another embodiment of the high-directional coupler according to the present invention. The embodiment of FIG. 3 is the same as the embodiment of FIG. 2, except that the 90 degree coupler 124 is a zero degree coupler 1
30 and the conductive line 132 is replaced by a second
It is arranged between the directional coupler 122 and the zero-degree coupler 130. Unlike the 90 degree combiner 124, the zero degree combiner 130 does not rotate the phases of the second forward signal and the backward signal before combining them with the first forward signal and the backward signal. In this embodiment, zero degree coupler 130 is a 3 dB Wilkenson coupler coupler.

The conductive line 132 is of a length such that the second forward and reverse signals are rotated 90 degrees before being applied to the zero-degree coupler 130. As a result, the zero-degree coupler 1
30 and conductive line 132 operate identically to 90 degree combiner 124 in that they combine to produce a combined forward and reverse signal. Therefore,
The directional couplers in this embodiment and the previous embodiment have a large high directivity.

As a modification of the present invention, for example, a third directional coupler is added in series with respect to the first and second directional couplers 120 and 122, and three directional couplers are used instead of the two-way coupler. A directional coupler is used. Of course, the phase difference between the combined signals must be adjusted (eg, by adjusting the distance between the couplers), and
The combiner must have the appropriate phase shift built in or added immediately before, so that the forward signals are combined and the backward signals cancel. The number of directional couplers is not limited to two or three.

[Brief description of the drawings]

FIG. 1 shows a directional coupler according to the prior art.

FIG. 2 shows a directional coupler according to an embodiment of the present invention.

FIG. 3 is a directional coupler according to another embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transmission line 20 Directional coupler 24 Resistance 100 Transmission line 120 First directional coupler 122 Second directional coupler 124 90 degree coupler 126 Forward signal output 128 Reverse signal output 130 Zero degree coupler 132 Conductive line

Continuation of front page (71) Applicant 596077259 600 Mountain Avenue, Murray Hill, New Jersey 07974-0636 U.S.A. S. A.

Claims (12)

[Claims] A transmission line (100) and a first coupler (1) coupled to the transmission line (100).
20); and a second coupler (1) coupled to the transmission line (100).
22), and a coupler (124) having a first input connected to the first coupler (120) and a second input connected to the second coupler (122). Directional coupler. 2. The directional coupler according to claim 1, wherein the coupler is a 90-degree coupler. 3. The directional coupler according to claim 1, wherein said combiner is a zero degree combiner. 4. The directional coupler according to claim 3, wherein the zero-degree coupler is a Wilkinson coupler. 5. The first and second couplers (120, 12).
2. The directional coupler according to claim 1, wherein 2) has the same configuration. 6. The first and second couplers (120, 12).
2. The directional coupler according to claim 1, wherein 2) is a 30 dB coupler. 7. The first and second couplers (120, 12).
2) combining the forward signals from the transmission line to form a second
2. The directional coupler according to claim 1, wherein the coupler couples signals that are 270 degrees out of phase from the first coupler. 8. The directional coupler according to claim 7, wherein said coupler is a 90-degree coupler. 9. A conductive line (132) connecting the second coupler (122) to the coupler (130), wherein the coupler (130) is coupled from first and second couplers. The directional coupler according to claim 7, wherein the coupler receives a forward signal having the same phase, and the coupler is a zero-degree coupler. 10. The first coupler combines a first forward signal from a signal on the transmission line, the second coupler combines a second forward signal from a signal on the transmission line, The directional coupler according to claim 1, wherein the combiner combines the first and second forward signals in an adding manner. 11. The first coupler combines a first reverse signal, the second coupler combines a second reverse signal, and the combiner includes the first and second reverse signals. 11. The directional coupler of claim 10, wherein the first and second reverse signals are canceled as a result. 12. The apparatus according to claim 1, wherein the first coupler, the second coupler and the coupler are arranged and configured such that forward signals from the first and second couplers are coupled in phase. The directional coupler according to claim 1.