JP2000134011A - Directional coupler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the rate of change in the coupling coefficient resulting from a deviation in relative position due to a manufacture error in the layout of strip lines. SOLUTION: Strip lines 5, 6 are unevenly structured in vertical directions in a way that the pattern of the one strip line is asymmetric to that of the other at a midpoint (a point of λg/8) of a length λ g/4 of the horizontally close-coupled part of the strip lines 5, 6. In each of the strip lines 5, 6, the upper part of the one strip line of this uneven structure is vertically on top of the lower part of the other. Thus, a change in the overlapped area of the parts of both in the vertical direction can be cancelled by the parts of both in existence horizontally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a directional coupler used for a frequency discriminator for detecting a frequency of a received signal.

[0002]

2. Description of the Related Art As a directional coupler used for a frequency discriminator or the like, a directional coupler having a triplate structure of a coupling line type using a strip line is known.

FIG. 4 shows a cross-sectional structure of such a directional coupler.

In the figure, reference numerals 10, 20, and 30 denote three-layer dielectric substrates, and reference numerals 40 and 50 denote strip lines formed by a conductor pattern formed with a central dielectric substrate 20 interposed therebetween. 70 is a metal conductor.

Next, an example of a strip line pattern in such a directional coupler is shown in FIG.

FIG. 5 shows the arrangement of the strip lines 40 and 50 as viewed from a direction perpendicular to the substrate surface.

As shown, strip lines 40,
The reference numeral 50 is arranged so as to partially overlap in the width direction of the strip lines 40 and 50 when viewed from a direction perpendicular to the substrate surface. The length in the line length direction of the strip lines 40 and 50 that partially overlap in the width direction is generally λg / 4, where λg is the effective wavelength of the target signal.

According to the directional coupler having such a structure,
The signal input from the end 1 of the strip line 40 is output from the end 3 after being tightly coupled to the strip line 50 at a portion having a length of λg / 4 that partially overlaps in the width direction. On the other hand, a signal tightly coupled to the strip line 50 is output from the end 2 of the strip line 50. The end 4 of the strip line 50 is an isolation port, and almost no signal is output due to tight coupling of the input signal.

[0009]

The strip lines as shown in FIGS. 4 and 5 are formed on the upper and lower surfaces of the dielectric substrate by a method such as etching, but are different from each other due to manufacturing precision and errors. The relative positions of the strip lines 40 and 50 formed on the substrate surface in the horizontal direction with respect to the substrate surface may deviate from design values.

Now, referring to FIG.
The width W1 of the tightly-coupled portions 0 and 50 = 0.45 mm, the length W2 not overlapping in the width direction = 0.23, the coupling coefficient -2.2 db, and the upper and lower substrates 1
0, 30 thickness 0.79 mm, center substrate 20 thickness 0.05 m
m, permittivity ε of the substrates 10, 20, and 30 = 2.2, λg / 4 = 1
It is assumed that 2.5 mm is a design value.

In this case, when the relative position is shifted in a direction in which W2 decreases by 0.02 mm, when the relative position is shifted in a direction in which W2 increases by 0.02 mm, and when W2 is 0.23 as designed. FIG. 6 shows a simulation result of the frequency characteristics of the outputs of the terminals 2 and 3.

As shown in the drawing, the coupling coefficient changes by 0.25 db with respect to the deviation of W2 ± 0.02 mm, and the rate of change of the coupling coefficient with respect to the deviation of the relative position in the width direction of the strip line at the tightly coupled portion is: , 0.25 / 0.04 = 6.2 db / mm.

Accordingly, the present invention provides a directional coupler having a structure capable of reducing a rate of change of a coupling coefficient with respect to a change in a relative position of a tightly-coupled portion in a horizontal direction with respect to a substrate surface of a strip line. The task is to provide.

[0014]

In order to achieve the above object,
The present invention is, for example, a directional coupler having two strip lines formed with a dielectric substrate interposed therebetween, wherein each strip line has a first region and a first region. A second region formed at a position shifted in one of two horizontal directions of the strip line and a horizontal direction, wherein each of the strip lines is one of the first regions of the strip line. Is arranged such that a portion of the second region of the other split line overlaps with a portion of the second region in the direction opposite to the one direction when viewed from a direction perpendicular to the substrate surface. A directional coupler is provided.

According to such a directional coupler, two directional couplers are arranged in the direction in which the area of the overlapping portion between the first region of the first strip line and the second region of the second strip line increases / decreases. If the strip lines are manufactured with a misalignment in the width direction, the area of the overlapping portion of the second region of the first strip line and the second region of the second strip line decreases / increases. Since the change in the area of the overlapping portion is canceled out, the rate of change of the engagement coefficient with respect to the displacement of the two strip lines in the width direction is reduced.

[0016]

Embodiments of the present invention will be described below.

First, a first embodiment will be described.

FIG. 1 shows a strip line pattern of the directional coupler according to the present embodiment.

Hereinafter, for the sake of convenience, description will be made using the vertical and horizontal directions of the drawing. As shown in the drawing, the line length direction of the tightly coupled portions of the strip lines 5 and 6 is the left and right direction in design values, and the width of the tightly coupled portions is The direction is the vertical direction. Also,
Each of the strip lines 5 and 6 has a stepped structure in which the pattern is shifted in the vertical direction at a half λg / 8 of the tightly coupled portion having a length of λg / 4. In and, the direction in which the pattern shifts at the point of the length of λg / 8 is reversed.

In the figure, when viewed from left to right, the strip line 5 has a structure in which the pattern shifts downward at the point of λg / 8, and when viewed from left to right, the strip line 6 , Λg / 8, the pattern is shifted upward.

The lower side of the strip line 5 having a length of λg / 8 shifted relatively upward, and the upper side of the strip line 6 having a portion of λg / 8 shifted relatively downward, Are arranged so as to partially overlap with each other in the vertical direction, and the upper part of the length λg / 8 which is relatively shifted downward in the strip line 5 and the λg shifted relatively upward in the strip line 6. The lower part of the portion having a length of / 8 is disposed so as to partially overlap in the vertical direction.

For example, in the drawing, the lower side of the length of λg / 8 on the left side of the tightly coupled portion of the strip line 5 and the upper side of the length of λg / 8 on the left side of the tightly coupled portion of the strip line 6 are shown. Are arranged so as to partially overlap each other when viewed from a direction perpendicular to the drawing, and the upper side of the λg / 8 length portion on the right side of the tightly coupled portion of the strip line 5 and the tightly coupled portion of the strip line 6 It is designed so that the lower side of the portion having the length of λg / 8 on the right side partially overlaps when viewed from a direction perpendicular to the drawing.

In such a structure, the signal input from the end 1 of the strip line 5 in FIG. .Gamma.g / 8 on the right side of the tightly coupled portion of the strip line 5
In the length of, the signal is output from the end 3 of the strip line 5 after being tightly coupled to the strip line 6 above the strip line 5. On the other hand, a signal tightly coupled to the strip line 6 is output from the end 2 of the strip line 6. The end 4 of the strip line 6 is an isolation port, and almost no signal is output due to tight coupling of the input signal.

As can be understood from the arrangement shown in FIG. 1, according to the directional coupler having such a structure, the relative positions of the strip line 5 and the strip line 6 in the vertical direction during the manufacturing are determined from the design values. In the case of displacement, the change in the area of the overlapping portion of the strip line 5 and the strip line 6 when viewed from the direction perpendicular to the drawing due to the displacement is offset on the left and right sides of the tightly coupled portion.

For example, in FIG. 1, when the strip line 6 is shifted upward relative to the strip line 5, the area of the overlapping portion on the left side of the tightly coupled portion increases, but the area of the overlapping portion on the right side increases. The area decreases accordingly.

Therefore, it is possible to reduce the rate of change of the coupling coefficient in the vertical direction with respect to the change of the relative position in the horizontal direction with respect to the substrate surface of the strip line of the tightly coupled portion.

Here, in order to show this effect, FIG.
As in the simulation shown in (1), the width W1
= 0.45 mm, length W2 not overlapping in the width direction = 0.23, coupling coefficient -2.2 db, thickness of upper and lower substrates 10 and 30 0.79 mm, thickness of central substrate 20 0.05 mm, substrates 10, 20, 30 When the dielectric constant ε = 2.2 and λg / 4 = 12.5 mm are the design values,
FIG. 2 shows the simulation results of the frequency characteristics of the outputs at end 2 and end 3 when W2 is shifted by ± 0.16 mm relative position and when W2 is 0.23 as designed.

As shown in the drawing, the coupling coefficient changes by 0.14 db with respect to the deviation of W2 ± 0.16 mm, and the rate of change of the coupling coefficient with respect to the deviation of the relative position in the width direction of the strip line at the tightly coupled portion is: , 0.14 / 0.32 = 0.44 db / mm, which is much smaller than 6.2 db / mm in the conventional directional coupler.

The first embodiment of the present invention has been described above.

As understood from the above description,
Strip line 5 and strip line 6 shown in FIG.
When the left-right relationship of the steps is reversed, and viewed from left to right,
The strip line 5 has a structure in which the pattern shifts upward at the point of λg / 8, and when viewed from left to right, the strip line 6 has a structure in which the pattern shifts downward at the point of λg / 8. You may have it. Of course, also in this case, the lower side of the length of λg / 8 shifted relatively upward in the strip line 5 and the upper side of the portion of λg / 8 shifted relatively downward in the strip line 6. Are arranged so as to partially overlap each other when viewed from the direction perpendicular to the drawing, and the upper side of the portion of λg / 8 shifted relatively downward of the strip line 5 and the relative position of the strip line 6 The design is made such that the lower side of the portion having a length of λg / 8, which is shifted upward, partially overlaps when viewed from the direction perpendicular to the drawing.

Hereinafter, a second embodiment of the present invention will be described.

FIG. 3 shows a strip line pattern in the directional coupler of the directional coupler according to the present embodiment.

Hereinafter, similarly to the first embodiment, the directional coupler according to the present embodiment will be described with reference to the vertical and horizontal directions of the drawing for convenience.
As in the first embodiment, the line length direction of the strip lines 5 and 6 is the left-right direction, the width direction is the vertical direction, and the line length direction of the strip lines 5 and 6 perpendicular to this portion is the vertical direction. , The width direction includes a portion in the left-right direction.

Therefore, in the second embodiment, as in the first embodiment, the line length direction of the strip lines 5 and 6 is the left-right direction, and the portion where the width direction is the up-down direction is the same as the first embodiment. Applying the same structure, the structure of the first embodiment is rotated by 90 degrees for each of the portions where the line length direction of the strip lines 5 and 6 perpendicular to this portion is the vertical direction and the width direction is the horizontal direction. Apply the structure.

In this way, when the relative positions of the strip line 5 and the strip line 6 deviate from the design values in the left-right direction during manufacturing, the lengths of the strip lines 5 and 6 become vertical. The change in the area of the closely-coupled portion of the overlapping portion of the strip lines 5 and 6 viewed from the direction perpendicular to the drawing due to the deviation from the design value is expressed by:
The line length directions of the strip lines 5 and 6 can be offset on the upper side and the lower side of the tightly coupled portion where the vertical direction is the vertical direction.

Therefore, according to the second embodiment, the coupling coefficient with respect to the change in the relative position in the horizontal direction with respect to the substrate surface of the strip line of the tightly coupled portion with respect to the deviation from the design value in the vertical direction and the horizontal direction. Can be reduced.

As in the first embodiment, the line length direction of the strip lines 5 and 6 is the horizontal direction and the width direction is the vertical direction, and the line length of the strip lines 5 and 6 is the same as in the first embodiment. Similarly to the second embodiment, when the direction includes a portion inclined at A degrees with respect to the left-right direction and the width direction is inclined at A degrees with respect to the up-down direction, the line length direction of the strip lines 5, 6 Is the left-right direction, and the same structure as in the first embodiment is applied to the portion where the width direction is the up-down direction, the line length direction of the strip lines 5 and 6 is inclined by A degrees with respect to the left-right direction, A structure obtained by rotating the structure of the first embodiment by A degrees may be applied to each of the portions inclined by A degrees with respect to the vertical direction.

[0038]

As described above, according to the present invention, a structure capable of further reducing the rate of change of the coupling coefficient with respect to the change in the relative position of the tightly coupled portion in the horizontal direction with respect to the substrate surface of the strip line. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a strip line pattern in a directional coupler according to a first embodiment of the present invention.

FIG. 2 shows a directional coupler according to the first embodiment of the present invention;
FIG. 9 is a diagram illustrating a simulation result of frequency characteristics with respect to misalignment.

FIG. 3 is a diagram showing a strip line pattern in the directional coupler according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a cross-sectional structure of a conventional directional coupler.

FIG. 5 is a diagram showing a strip line pattern in a conventional directional coupler.

FIG. 6 is a diagram showing a simulation result of a frequency characteristic of a conventional directional coupler with respect to a displacement.

[Explanation of symbols]

 10, 20, 30 Dielectric substrate 4, 5, 40, 50 Stripline 60, 70 Metal conductor

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[Procedure amendment]

[Submission date] November 19, 1998 (1998.11.
19)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

Claims (3)

[Claims] 1. A directional coupler having two strip lines formed with a dielectric substrate interposed therebetween, wherein each strip line includes a first region and a first region. A second region formed at a position shifted in one of the two width directions and the horizontal direction of the strip line, wherein each strip line has one of the first regions of the first region of the strip line. The portion in the direction opposite to the one direction of the second region of the other split line overlaps with the portion in the direction opposite to the one direction when viewed from a direction perpendicular to the substrate surface. A directional coupler, comprising: 2. A directional coupler having two strip lines formed with a dielectric substrate interposed therebetween, wherein each strip line has a first direction parallel to the substrate surface and a line length direction. And a portion having a second direction different from the first direction parallel to the substrate surface as a line length direction. For each of the portions, each strip line includes a first region, A second region formed at a position shifted in one of two directions of the width direction and the horizontal direction of the strip line with respect to the first region; The portion from the one direction is arranged so as to overlap with the portion of the second region of the other split line in the direction opposite to the one direction when viewed from a direction perpendicular to the substrate surface. Directional coupler characterized by being performed. 3. The directional coupler according to claim 1, wherein the strip line included in the first region and the second line are connected to each other.
The directional coupler, wherein the line lengths of the strip lines included in the regions are equal.