JPH04111501A - Directional coupler - Google Patents

Abstract

PURPOSE:To obtain a high directionality by distributing a signal into two to give a phase difference and synthesizing signals again after taking out them by directional couplers and not only efficiently synthesizing effective signals but also excluding unnecessary signals by the phase difference. CONSTITUTION:The high frequency power inputted from a point 1 is outputted to power lines 14a and 14b as signals Pi1a and Pi1b by a 3dB coupler 12a, and they are inputted to directional couplers 13a and 13b having a coupling degree C. In directional couplers, the signal Pi1a is partially coupled with a signal Pi2a outputted to a power line 16a and a signal going to a resistive terminator in accordance with the degree C of coupling, and a signal Pi2b is taken out from the signal Pi1b in the same manner. That is, the signal is distributed to two main lines with the same amplitude by the distributor, and signals are taken out from these signals, to which the phase difference is given, by two directional couplers 13a and 13b, and taken-out signals are synthesized to obtain a coupling degree, and signals hindering the directionality are led to resistive terminators 11a to 11c by the phase difference. Thus, a high directionality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a directional coupler mainly used in a high frequency band.

[Conventional technology]

FIG. 4 is a block diagram of a conventional directional coupler, and FIG. 5 is an exploded view of the same. In these figures, 1 and 2 are input terminals, 3 is an output terminal, 5a is a primary side coupling line, and 5b
is the secondary side coupled line.

Next, the operation will be explained.

The high frequency power P11 input from input terminal 1 propagates through the primary side coupling line and is output to input terminal 2.
A part of it is outputted to the output terminal 3 as Pl due to electromagnetic coupling with the next side coupling line 5b. A portion also goes to the non-reflection terminator 4 as P 12, but 20 PI! is absorbed by the non-reflection terminator and disappears. Here, when a non-reflection terminator is connected to the input terminal 2, C expressed by is generally called the degree of coupling.

Conversely, a portion of the high frequency power Prl input from the input terminal 2 is similarly outputted to the output terminal 3 as P, 2, and a portion goes to the non-reflection terminator 4 as Pr3, where it is absorbed and disappears. Here, when a non-reflection terminator is connected to the input terminal l, I, which is expressed as , is generally called isolation.

Also, D=　I　I-Cl　(dB) D, which is expressed as , is called directionality.

[Problem to be solved by the invention]

The conventional directional coupler is configured as described above, and the combined output Pr2 due to the incident power p r+ from the input terminal 2
It is desirable that no P r2 exists and that the generated P r2 is completely absorbed by the non-reflection terminator, resulting in infinite isolation and coupling. However, in reality, P r2 exists and the generated P r2 is not completely absorbed by the non-reflective terminator but is partially reflected and goes to the output terminal 3, so the directionality of this type of directional coupler is is generally 22dB to 40d
There was a problem that only a value of about B could be obtained.

The object of this invention is to obtain a directional coupler with a high directionality of 30 to 50 dB.

[Means for Solving the Problems] The directional coupler according to the present invention distributes signals with equal amplitude to two main lines using a divider, and separates two signals from a signal having a phase difference.
The signal is taken out by two directional couplers, and the degree of coupling is obtained by combining the taken out signals, and the signal that obstructs the directionality is guided to the non-reflection terminator due to the phase difference.

[Effect]

In this invention, an input signal is divided into two series of signals with equal amplitude and a phase difference, a signal is extracted from each signal using two directional couplers, and the extracted signals are combined to obtain the degree of coupling. In addition, since the structure is configured such that a signal that obstructs directivity is guided to the non-reflection terminator due to a phase difference, the directivity is not deteriorated and a large directivity can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a directional coupler according to the present invention. In the figure, 12a, 12b, and 12c are 3 dB couplers, and 13a, 13b are directional couplers with arbitrary coupling degree C, lla, and llb.

11c is a non-reflection terminator.

Also, 14a, 14b, 15a, 15b, 16a, 16
b are electrical transmission lines having the same length.

Points 1-10 indicate positions.

Next, the operation will be explained.

The high frequency power input from point l is connected to transmission lines 14a and 14b by a 3dB coupler 12a, respectively.
It is output as I P ITo. P llb is P l
Compared to the 1m signal, the amplitude is the same, but the phase is delayed by 90°.

Next, P lla + P I11+ each have the degree of coupling C
directional couplers 13a and 13b having the following characteristics. As in the prior art, within the directional coupler, P l1m is partially coupled to the signal P,2° output to the transmission line 16a and to the signal directed to the non-reflection terminator, corresponding to the degree of coupling C. Also P l
Similarly, a signal called Pllb is extracted from lb. The remaining signal P1 partially taken out in the directional coupler
411 I P tab are each input to the 3 dB combiner (12c) while maintaining the aforementioned 90' phase difference, but since they have the same amplitude but a 90° phase difference, they are combined, and from point 6 to P+6 It will be output as Similarly, the signal P 12m + extracted by the 3 dB coupler
Since P 12b has the same amplitude and a phase difference of 90°, they are combined and output as P 11 to point lO. This P, 2/P, can be redefined with the degree of coupling C.

Next, consider the input P from point 6. The input high frequency power P is connected to the transmission line 15 by the 3 dB coupler 12c.
a and 15b as P rla + P and 1b, respectively, or p r+ is a signal that has the same amplitude but a phase delayed by 90° compared to P rlb.

In the directional coupler, P+2a+ as in the case of input P,
P, 2. goes to the 3dB coupler 12b. In addition, the signal reflected by the non-reflection terminator in the directional coupler also goes to the 3 dB coupler 12b, but since the phase lead/lag of this signal is reversed compared to the case of P 12a I P rib described above. , the combined signal is absorbed by the non-reflection terminator 11b as Pr2 and is not output to point 10. The remaining signals combined by the directional coupler are combined by the 3 dB coupler 12a and output to point 1 as Pt6. Isolation is the ratio of the input at point 6 to the output at point lO,
Since the input P at point 6 does not appear at point 10, the isolation becomes infinite. As a result, the directionality becomes infinite.

In the above embodiment, the 3 dB couplers 12a and 12c were used, or as shown in FIG.
20b and 90° phase shifters 21a and 21b, P I
Is r P llb amplitude 9 phase relationship, and P
Since the amplitude two-phase relationship of rim + P rlb is the same as in the above embodiment, similar effects can be achieved.

Also, in Figure 3, a 90° phase shifter 21 is used instead of a 3dB coupler.
In this example, P12arP1□ are the same amplitude,
Since they are in the same phase, they are combined without loss in the Wilkinson type two-way distribution 22a, but the unnecessary signal P r2a
+P r2b The amplitudes are the same, but the phases are shifted, so they are not combined sufficiently and are output to point 10 with some loss.

2, the isolation will not become infinite, but will be improved compared to the prior art.

〔Effect of the invention〕

As described above, according to the present invention, the directional coupler is configured to divide the signal into two parts, give a phase difference, take out the signals by the directional coupler, and then combine them again. This has the effect that effective signals can be efficiently combined and unnecessary signals can be eliminated, and as a result, great directionality can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a directional coupler according to one embodiment of the invention, FIGS. 2 and 3 are diagrams showing other embodiments of the invention,
FIG. 4 is a block diagram of a conventional directional coupler, and FIG. 5 is an exploded view of the conventional directional coupler. In the figure, 12a, 12b, 12c are 3dB couplers,
13a and 13b are directional couplers having an arbitrary coupling degree C;
lla, llb, llc are non-reflection terminators, 14a and 14
b, 15a and 15b, and 16a and 16b are transmission lines having the same length. Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1

Claims (1)

[Claims] (1) Assign the input signal as a signal with equal amplitude and a phase difference.
a splitter that distributes to a series of lines; two directional couplers that extract a part of the signal from each of the distributed signals; and a first directional coupler that combines the two signals extracted by the directional couplers.
A directional coupler comprising: a combiner; and a second combiner that combines two signals remaining without being taken out by the directional coupler.