JPS6165503A - Directional coupler - Google Patents

Abstract

PURPOSE:To adjust easily coupling degree without changing the coupling degree of each distributed coupling line by coupling a main line of a distributed coupling line having a different electric length in cascade and synthesizing outputs of a sub line side into the same phase at an output synthesizer via a phase shifter circuit and a connecting line respectively. CONSTITUTION:Electric lengths of distributed coupling lines 11-1, 11-2,...,11-n are respectively theta, 2theta,...,ntheta and the coupling coefficients are k1, k2,...,kn. Main lines 12-1m 12-2,...,12-n of each distributed coupling line are connected in cas cade. Further, sub lines 13-1, 13-2,...,13-n of each distributed coupling line are terminated respectively by dummy loads 14-1, 14-2,...,14-n at each non-coupling terminal, and coupling terminals 16-1, 16-2,...,16-n are connected to an output synthesizer 19 via phase shift circuits 17-1, 17-2,...,17-n and connecting lines 18-1, 18-2,...,18-b respectively and a synthesized output is obtained from a termi nal 20 of the output synthesizer 19. Thus, a uniform coupling characteristic over a wide band is obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a directional coupler constructed using distributed coupled lines, and particularly relates to a directional coupler constructed using distributed coupled lines, in particular a directional coupler configured by cascading the main line sides of a plurality of distributed coupled lines having different electrical lengths. The present invention relates to a directional coupler that can obtain uniform coupling characteristics over a wide band by coupling the sub-line side outputs with the same phase.

[Conventional technology]

Broadband directional couplers using distributed coupling lines are already known. FIG. 10 shows the configuration of a conventional distributed coupling type directional coupler, in which a large number of distributed coupling lines L1, 1-2. ..., 1-n are connected in cascade, and one element of each 2-1, 2-2, ...
・, 2-n is connected between both terminals 4.5 of the line as the main line, and each other element 11, 3-2
,...,6. Both terminals 6, 7 of the line connecting -n
Each coupled line 1-1.1-2 is used as a sub line between
,..., the degree of bonding in 1-n is 1. k2. -,
By appropriately selecting kT1ft, it is possible to obtain a broadband directional coupling output between the terminals 6° and 7 of the sub-line.

[Interface point that the invention attempts to solve]

In the conventional directional coupler shown in Figure 10, the value of the degree of coupling in each coupling line directly affects the performance of the directional coupler, so adjustment work is required to achieve the desired performance. There was a problem that it took a lot of time.

[Means for solving problems]

In the directional coupler of the present invention, the main line sides of a plurality of distributed coupling lines having different electrical lengths are coupled in a cascade, and the output from the sub line side is outputted via the phase shift circuit z and the L connection line. In addition to the combiner, a directional coupling output is obtained by combining the outputs in the same phase.

[Effect]

According to the directional coupler of the present invention, each distributed coupled line itself can be It is possible to effectively change the degree of bonding without changing the degree of bonding. Therefore, in order to achieve the desired characteristics in the directional coupler, each distributed coupling line must be coupled 1! It becomes possible to perform adjustment work by making changes independent of other distributed coupling lines.

〔Example〕

..., main line of ILn, 13-1.15-2. ...
, 15-n are each distributed coupling line 1L1.11-2.・・・
・, 11-n sub-line, 14-1° 14-2. ...,
14-n are each sub-line 111.112. ..., 13-
Dummy load of n, 15-j, 1s,...
15-n, 15-(n+1) are terminals of main lines connected in cascade, 16-1°16-2. ..., 16-
, are each sub-line IL1, 13-2,..., 15-
n coupling terminal, 17-1.17-2,..., 17
-n is each sub line IL1.15-2,..., 13-
Phase shift circuit for the output of fl, IELl, 1s-2
,..., 18-n is each sub line 16-1, 13-2
．． ....

13-n is a connection line for the output; 19 is an output combiner;
20 is a composite output terminal.

Distributed coupling lines IL1, 1i-2,..., 11-11
have electrical lengths θ, 2θ, . . . , nθ, and a coupling coefficient of 1. k2. ..., kn. Main lines 12-1, 12-2, ..., 1 of each distributed coupling line
2-n are connected in cascade. In addition, the sub lines 15-, , 15-2°, . 1
, 14-2. ..., 14-n, and the respective coupling terminals 16-, , 16-2, .
..., 16-n are phase shift circuits 17-1, 17-, respectively.
2. ..., 17-n and connection line IL1, 18-2
, . Note that the above-mentioned dummy load is for the purpose of absorbing reflected waves by the output combiner 19, and may be omitted if the performance of the output combiner is good.

When a unit wave is now added to the input terminal 15-1 of the main line, the output wave at the coupling terminal 16-1 of the i (i = 1 * 2 *...tn)-th sub line is as follows. You can ask for it.

FIG. 2 shows a distributed coupling line. 21°22
are strip lines constituting a distributed coupling line, and θ is the electrical length of each strip line.

Assuming that the input and output terminals of this distributed coupling line are 1, 2, 2, and 2, the transmission characteristics in the main line and the coupled transmission characteristics between the main line and the sub-line are expressed as follows.

Here, TI2 is a transmission coefficient between terminals ■ and ■, T15 is a transmission coefficient between terminals ■ and ■, and k is a coupling coefficient between both main and sub lines. The coupling coefficient has the following relationship with the characteristic impedances Zoe and Zoo of the odd mode.

Here, Zo is the reference impedance (load impedance and power source impedance), and the above equation +11, +2) is based on the following equation zo=E;1=...(6), which is a violation of equation (5). It was derived as follows.

Now, the degree of connectivity in the coupled line is small, so k is 1
...17), then equations (1) and +2) can be approximated as follows.

Ayu 2ki. -jθ...(8)
T mo jkmθ−jθ ...(
9) By referring to equation (81, (9)), when adding the unit wave to the input terminal 15-1, the wave output to the input terminal 16-1 of the first sub-line is as follows. become that way.

-jJmθ jki field (iθ), m-1... When this output wave is output to the output terminal 20 via the output combiner 19, the phase shift circuit 17-1 and the connecting line 18-1
After applying the phase delay Yi, the result is as follows.

-j ('Fi+Σmθ) jki*(iθ)・ 1-1 °°°
(6) Similarly, the output of the output terminal 20 based on the n-th coupler 11-n is jki. ,. ,). −j integer °”), , , 2m=j.Here, i=1.2..., for n, ′y
By omitting i, it can be expressed as in the following equation.

T=, Σklsin (iθ) ・
C1411=1 The α1 formula is an l'ourisr series, and the coupling coefficient kl
By appropriately selecting the Fouri
It is possible to widen the band by performing sr class intermittent synthesis.

FIG. 3 shows the characteristics of an ideal coupler, in which the output T alternates between +1 and -1 for every change in π of the electrical length θ. When the function shown in FIG. 3 is expanded in a Pouriar series, the following relationship is obtained in the well-known process 5.

Comparing the CI4 formula and the Kari formula, 2i=0
...u′i), the coupling coefficient from the input end to the composite output end is Fourier
r It is a slope U approximation. That is, the characteristics in this state are as follows.

Assuming that θ=- when the frequency af=fc (center frequency), the expression of the characteristic in the frequency domain is as follows.

FIG. 4 shows the results of calculating the frequency characteristics of the degree of coupling using the α bar formula and setting the reference coupling amount to -20 dB for fc = 9.5 GHz. In the figure, n = 1 indicates the case of a single coupler, and it is shown that by setting n = 2 or 3, the effect of widening the band design is significantly greater than in the case of a single coupler.

Next, if the output of the composite output terminal 20 in the distributed directional coupler shown in FIG. 1 is determined strictly, it will be as follows.

vfm=Σ(2A-1)θ・
・・When 4t, -m+madashi m = n, vm = 0
...QυTyyl = ward T12 gate 'rj3'''
"11n""1(i) However, when m=1, TT12=1...(
to) i:1 1 4kQ k2i-1=□-η1 °°°(1)2
1-1 π However, ye1 = correction coefficient (C) ~ The reason why only the odd terms are given in equations (C) is because the approximation described above for Figure 3 is assumed, and generally the even terms are also included. There is a need. Equation (c) is a continuation of the above-mentioned aQ equation, but it is multiplied by a correction coefficient η1 so that a computer simulation can be performed by changing the value.

FIG. 5 shows an example of the characteristic calculation results of the phase-shifting and combining type directional coupler of the present invention, in the case where the number of coupled lines n = 5, and the above-mentioned correction coefficient values were all set to 1 (no correction). The case corresponds to the case of n=5 in FIG. The two agree very well, with a degree of coupling of -20d.
It has been confirmed that in the case of B level, the above-mentioned approximation theory is sufficient.

Figure 6 or W! Figure J8 shows the simulation by giving various values as correction coefficients for n = 5.
1 ← Both 4-pressure gauges are deteriorating ■ - A - 1 ' From the deterioration of the pressure gauge, in the case of Figure 5, there is a deviation from the design value (-20 dB) of the degree of coupling in the range of 2 to 17 GHz. Maximum t5d
It can be seen that, for example, in the case of FIG. 7, the improvement was from about B to about 1 dB. Furthermore, it can be seen from these results that even if the coupling coefficient changes by about dB, the characteristics do not change much. This shows that when manufacturing a directional coupler, it is possible to relax the requirements for manufacturing accuracy of the coupling line, which is advantageous in actual manufacturing.

Figure 9 shows an example of the results of characteristic calculations by simulation when the number of coupled lines is n = 4, and shows that the deviation from the design values of the bandwidth and degree of coupling is further improved compared to the case where n = 3. is clear.

〔Effect of the invention〕

As explained above, according to the directional coupler of the present invention, the main line sides of the distributed coupling lines having different electrical lengths are coupled in a cascade, and the outputs of the sub line sides are transmitted through the phase shift circuit and the connecting line. Since the output synthesizer synthesizes the signals in the same phase,
The desired characteristics of the directional coupler can be achieved by effectively adjusting the degree of coupling to two without changing the coupling between the distributed coupling lines, and therefore the adjustment work is greatly facilitated.

[Brief explanation of drawings]

Figure 1 (2) A diagram showing the configuration of an embodiment of the directional coupler of the present invention, Figure 2 is a diagram showing a distributed coupling line, Figure 6 is a diagram showing the characteristics of an ideal coupler, and Figure 4 Figures 5 to 9 show calculation results of the frequency characteristics of the coupling degree in the directional coupler of the present invention, respectively, by computer simulation. 10 is a diagram showing the configuration of a conventional distributed coupling type directional condenser. 1-1.1-2+...+1-n'distributed coupling line,
2-1 w 2-2 +...+ 2-n+ 3-1+
3-2+...+! '-n' distribution sweet wire distribution connection line, 5: main line terminal, 6, 7: sub line terminal, 11-1
111-21..., 11-,: distributed coupling line, 12-
1+12-2+..., 12-n: Main line, 1!1-1
11!1-21..., 1.5-n: Sub line, 14-1
．． 14-2. ..., 14-n: dummy load, 15-
1+ 15-2+...$l5-no 15-(n+1
) "Main line terminals, 16-1+ 16-2+...,
16-n coupling terminal of two sub-lines, i7-++17-2.
..., 17-n: Ginso circuit, 18-1.18-2.
.... 1B-n: Connecting line, 19: Output magnifier, 201- Output terminal Patent application filed Sumitomo Electric Industries Co., Ltd. Agent Patent attorney Hisashi Tama 5-〇40
Mountain-N no gu 0 ■ To no (ri・・・・・・・・・・ [phase]

Claims (6)

[Claims] (1) A plurality of distributed coupling lines each having a different electrical length, a plurality of phase shift circuits each connected to the output on the sub line side of each of the distributed coupling lines, and each connected to the output of each of the phase shift circuits. The main line side of each of the distributed coupling lines is connected in cascade to add an input, and the main line side of each of the distributed coupling lines is connected in cascade, and the input is added to each sub line side. A directional coupler, characterized in that outputs are combined into the same phase at the output of the output combiner by respective phase shift circuits and connection lines. (2) By inserting an attenuator into each of the phase shift circuits or connection lines provided on the output side of each sub-line, and setting the degree of attenuation of each attenuator, the degree of coupling in each coupling line can be effectively changed. The directional coupler according to claim 1, characterized in that the directional coupler is configured to be able to perform the following functions. (3) The degree of coupling in each coupling line can be effectively changed by selecting a distribution ratio for each sub-line output in the output combiner. The directional coupler according to item 2. (4) The electrical length of each distributed coupling line is selected to be θ and an odd multiple thereof, and the degree of coupling in each distributed coupling line is k_2_i_-_1=1/(2i-1)(4k_0)/
πηi However, k_2_i_-_1 is i (i=1, 2, ・
..., the coupling coefficient k_0 of the n)-th distributed coupling line and the reference coupling amount ηi are selected as correction coefficients for the i-th distributed coupling line. combiner. (5) The degree of coupling in each of the distributed coupling lines is effectively determined by the settings of a phase shift circuit or an attenuator inserted in the coupling line on the output side of each sub-line. Directional coupler as described in section. (6) The degree of coupling in each of the distributed coupling lines is effectively determined by selecting a distribution ratio for each sub-line output in the output combiner. directional coupler.