JPS63294103A - Three-branch line 3db hybrid circuit - Google Patents

Abstract

PURPOSE:To improve the isolation characteristic of a three-branch line 3dB hybrid circuit, by partially cutting off the branched section of the central one among the lines which are connected in parallel with input-output lines and making the band for degree of coupling and band for isolation characteristic coincident with each other. CONSTITUTION:This three-branch line 3dB hybrid circuit is composed of 1st lines 5 and 8 and 2nd lines 6 and 7 which are connected in series with input-and output-side lines 1-4 and lines 9-11 which are connected with the lines 5-8 in parallel. By making the impedance of the 1st and 2nd lines 5 and 8, and 6 and 7, equal to the impedance of the input-and output-side lines 1-4 and providing notched sections 12 and 13 in the 1st and 2nd lines 5 and 8, and 6 and 7, in the vicinity of the branched sections of the central line 10 of the parallel lines 9-11, the center frequency for degree of coupling is made coincident with the center frequency for isolation. Therefore, the isolation characteristic of this hybrid circuit can be improved.

Description

[Detailed description of the invention] (Keystone) A three-branch line that combines the coupling band and isolation band by cutting out a part of the central branch of the line parallel to the input/output line. 3dB bar f bridge circuit.

[Industrial application field]

The present invention provides power distribution using a microphone/comic/lip circuit.
This article relates to a three-branch line 3dB hybrid circuit used for synthesis.

Plunge line type 3 dB hybrid 1 circuits are used on the output side of single wave amplifiers, and are often of the 2 branch line type, not shown in Fig. 3.

The configuration and operation of this circuit is as known. 11 to ρ4 are each λ/'4 line, and if A is the input terminal, the input is transmitted through the line 7!1 to the output terminal C-1, and the line i11 and 144. IJ and β) to output terminal D-.

Finally B, and ρ4. Since βJ and β2 have the same length, D
By appropriately determining the line width (impedance), each of the input terminals 1. /2
(3dB) appears. Terminal B is connected to the input that has passed through line β3 and line ρl.

Since the inputs passing through 7f and β4 have a phase difference of λ/'2, they cancel each other out, and no input leaks to terminal B (ideal case). A dummy resistor for absorbing reflected waves is connected to this terminal B.

The plunge line type 3dB hybrid circuit shown in Fig. 3 has a simple configuration, but the frequency band is relatively narrow, and the practical band is about 10% of the fractional band. A three-branch line type with a two-stage connection structure is also used.

[Conventional technology]

FIG. 4 and FIG. 5 show a three-branch line type 3 dB Vibriso 1 circuit. 1.4 is the line on the input side, 2.3
is the line on the output side. 5 and 8 degrees, 6 and 7 are these people, the first one in series with the output side line. The second line, 9.10.
11 are three lines parallel to these, all of which have a length of λ
g/4.

The operation is similar to that shown in FIG. 3, with the input reaching output terminals 2 and 3 for 3 dB distribution. There is no leakage of input from the terminal 4-1, and a dummy resistor for absorbing reflected waves is generally connected to this terminal. This branch line type 3 dB hybrid circuit is used in balanced amplifiers, mixers, phase shifters, etc. when the frequency band is 20% or less of the center frequency.

In a three branch line 3dB hybrid circuit, if the impedance of each line is taken as shown, the parallel lines 9, 11 . and 10 impedances Zp1. Zpz
is known to be. If Zs1=Zo, (2
) formula is Z l) 2 = '2 Z o
−・=(31, and if Zo−50Ω, Zp+
=120°7Ω, Zp2=70.7Ω. Based on this value, λg /
Figure 5 shows the one made by changing 4 to 13,6 ta, and its characteristics are shown in Figure 6. In this diagram, 1-2 is input terminal 1
and output 2, and 1→3 indicate the frequency characteristics of each degree of coupling between input terminal 1 and output terminal 3, and 1-4 indicates the isolation between terminals 1 and 4.

From this graph, good results can be obtained regarding the degree of coupling, but the band with good artesion deviates from the designed value,
The center frequency of the degree of coupling (approximately 3.9 GHz) and the center frequency of isolation (the center frequency has not yet appeared in the solid line curve.This changes as shown by the dotted line, and the center frequency is 3.2~3. 3 GHz) is not correct.

In addition to this combination of line impedance, ■ZS+=
Z o / '2 = 35.4Ω, Zp+ = 120.
7Ω, Z I) 2 = Z o / '2 = 3
5.4Ω, and ■Zs+=AZo=70.7Ω, Zp
+, =120.7Ω, Zp2=2 2Zo”141.4
There is an Ω. ■ is generally used as the standard type because it has the best characteristics (widest band), but Z S I”: Z
Since it is O, the line width will be changed accordingly.

[Problem that the invention seeks to solve]

In the 3-branch line 3dB Hybridino 1-, the impedance of the central line 10 can be appropriately selected among the lines 5 to 8 connected in series with the human output line and the lines 9 to li connected in parallel. For ease of installation, the impedance of lines 5 to 8 connected in series with the input/output line is 50Ω, which is the same as that of the input/output line. The band deviates from the set δ1 value, causing a problem that the center frequency of coupling and the center frequency of isolation do not match.

The present invention aims to improve this by simple means and match the image frequencies.

[Means for solving problems]

As shown in FIG. 1, in the present invention, three brunge lines 3d
A notch 12 is formed by cutting out a part of the central branch 10 of the line connected in parallel with the input/output side line of the B hybrid.
, 13 are provided.

The rest is the same as in Figure 5, etc., 1 to 4 are people, output side lines, 5 and 8, 6 and 7 are first lines in series with these input and output side lines.
．． The second lines 9 to 11 together with the three lines in parallel constitute the main body of the circuit. Since these lines are composed of microphone I-1, 1, and 1 helinopran, there are ground conductor layers, 1, and insulating layers (not shown), and lines 1 to
11 is formed on this insulating layer 1-.

[Effect]

If cutouts 12 and 13 are created by cutting out a part of the lines 5 to 8 that are in series with the input/output line near the central branch 10 of the line parallel to the input/output line, the center frequency of isolation will be can be said to match the center frequency of the degree of coupling. This is because the formation of the notches 12 and 13 corrects the effects of discontinuities in beam dance at line branching parts, the inappropriateness of each line length, and each line width, and improves the isolation characteristics. It seems that

(Example) Figure 2 shows the frequency characteristics of the degree of coupling and isolation, using a differential glass substrate with a thickness of 0.81 mm,
The characteristics are shown when g/4 is 13.6 mm. As shown in the figure, the center frequency of coupling degree and the center frequency of isolation match well.

Although there is no particular change in the connectivity characteristics due to the pattern notch,
Isolation characteristics change.

To give a ten-dimensional example, both Ll and Lx in Fig. 1 are λg/4, and in this example, 13.6 am, 50Ω line I, 2°...
The width of ... is 2. I G i+i, 120.7Ω line 9
, 1], the width of the 70.7Ω line 10 is 1.20 am. Note that 2 is the distance between the centers of the line, and Ll is taken from the end of the line, and in terms of the distance between the centers, it is in the order of 13.6-12.1 G-] 5.7 G. The point taken from this end also contributes to the coincidence of the image frequencies.

[Results of invention]

As explained above, in the present invention, the aisle can be removed by a simple means of providing a notch 12.1.3 in the vicinity of the central branch of the line connected in parallel with the input/output line. By correcting the deviation of the band, it is possible to match the coupling degree band and the isolation band.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the hybrid circuit of the present invention, Fig. 2 is a characteristic diagram of the circuit shown in Fig. 1, Fig. 3 is an explanatory diagram of a conventional example, and Fig. 4 is a diagram of a 3-branch line 3dB vibratory 1-circuit. 5 is a plan view showing the specific example of FIG. 4, and FIG. 6 is a characteristic diagram of the circuit of FIG. 5. In Figure 1, 1 to 4 are people, output side lines, 5.8 are first lines, 6 and 7 are second lines, 9 to 11 are three parallel lines, and 12 and 13 are notches. be.

Claims (1)

[Claims] First lines (5, 8) and second lines (6, 7) in series with the lines (1, 2, 3, 4) on the input/output side, and three lines in parallel with these lines. In a three branch line 3dB hybrid circuit consisting of lines (9, 10, 11), the impedance of the first and second lines is the same as the impedance of the line on the input and output side, and the center of the three parallel lines is Notches (12, 1
3), and the three branch line 3dB hybrid circuit is characterized in that the center frequency of the degree of coupling and the center frequency of the isolation are matched.