JPH0567904A - Distribution coupling type directional coupler - Google Patents

Abstract

PURPOSE:To realize the distribution coupling type directional coupler with high degree of coupling, wide line interval and line width, reduced length of the line and ease of manufacture with respect to the distribution coupling type directional coupler employed for various communication equipment or the like. CONSTITUTION:A lumped constant capacitance 14 is added in the middle of two parallel-coupling lines in the distribution coupling type directional coupler to compensate the coupling of the parallel coupling lines. The distribution coupling type directional coupler is realized with a wide line interval and a wide line width and ease of manufacture on which the length of the line is designed to be short by adding a capacitance to ground from four input output terminals 11, 12, 13.

Description

Detailed Description of the Invention

[0001]

The present invention is used in the high frequency band,
The present invention relates to a distributed coupling type directional coupler having a high degree of coupling and easy to manufacture.

[0002]

2. Description of the Related Art Recently, in the field of mobile communication and the like, there is a strong demand for a distributed coupling type directional coupler having a high degree of coupling and easy to manufacture.

A conventional distributed coupling type directional coupler will be described below. Here, a microstrip line distributed coupling type directional coupler having a simple structure but low coupling will be described. FIG. 3 shows a conventional microstrip line distributed coupling type directional coupler. In FIG. 3, 1 is an input terminal, 2 is an output terminal, 3 is an isolation terminal, and 4 is a coupling line.

The operation of the microstrip line distributed coupling type directional coupler configured as described above will be described below. The conventional distributed coupling type directional coupler is
The two parallel coupling lines 4 are brought close to each other to perform electric field coupling and magnetic field coupling. A signal input to the input terminal 1 outputs signals having different phases to the two output terminals 2 and the isolation terminal 3 has a direction not to output a signal. When the line length of the coupled line 4 is λ _g / 4 at the center frequency, 90
A signal having a phase difference of ° is output. Here, in order to obtain the directivity, the ratio of electric field coupling and magnetic field coupling is adjusted, that is, the line width and line spacing of the parallel coupled line 4 are adjusted. Moreover, in order to increase the degree of coupling, it is necessary to reduce the line spacing. As a method of increasing the degree of coupling in the conventional distributed coupling type directional coupler, a distributed coupling type directional coupler using a strip line having an overlay structure has been considered.

[0005]

However, in the above conventional structure, it is necessary to make the line spacing sufficiently narrow in order to increase the coupling degree, but there is a limit to the line spacing in terms of dimensional accuracy and manufacturing. The degree of coupling is not sufficient, and even in the case of structurally increasing the degree of coupling, a stacking technique is required to accurately control the thickness of the dielectric layers to be stacked in order to stack the dielectric layers. In addition, a phase difference of 90 ° is provided. To obtain the output signal, set the line length of the coupled line to λ at the center frequency.
There was a problem that it had to be _g / 4.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and an object of the present invention is to provide a distributed coupling type directional coupler having a high degree of coupling, easy to manufacture, and capable of shortening the line length.

[0007]

In order to achieve this object, the present invention adds a lumped constant capacitance to the central portion of two parallel coupled lines, and connects four input / output terminals to ground for impedance matching. It is configured to add capacity to the.

[0008]

With the above structure, the present invention can increase the coupling degree by adding a lumped constant capacitance to the central portions of the two parallel coupled lines, and at the same time, can increase the line width and the line spacing of the parallel coupled lines. A distributed coupling type directional coupler that is easy to manufacture can be realized. Also, impedance matching is improved by adding capacitance from the four input / output terminals to the ground,
It is possible to realize a distributed coupling type directional coupler in which the length of the coupling line is shortened.

[0009]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a distributed coupling type directional coupler according to a first embodiment of the present invention. In FIG. 1, 1
Reference numeral 1 is an input terminal, 12 is an output input terminal, 13 is an isolation terminal, and 14 is a lumped constant capacitance. Since the electrode patterns are vertically and horizontally symmetrical, the input terminal 11 may be located at any position. However, a terminal located diagonally to the input terminal 11 becomes the isolation terminal 13.

The operation of the distributed coupling type directional coupler configured as described above will be described below. The signal input to the input terminal 11 has a directivity in which signals having different phases are output to the two output terminals 12 and no signal is output to the isolation terminal 13.

The characteristics of the distributed coupling type directional coupler according to this embodiment and the characteristics of the conventional distributed coupling type directional coupler are shown in Table 1 below.
It shows in comparison with.

[0013]

[Table 1]

As is clear from (Table 1), the distributed coupling type directional coupler according to this embodiment has a coupling degree of about 4 dB.
And good results are obtained, and an excellent effect is obtained in that the degree of bonding is high.

Further, the line data of the distributed coupling type directional coupler according to the present embodiment and the line data of the conventional distributed coupling type directional coupler are shown in comparison with each other (Table 2).

[0016]

[Table 2]

As is clear from (Table 2), the distributed coupling type directional coupler according to this embodiment is wider than the conventional distributed coupling type directional coupler in terms of line spacing and line width. An excellent effect is obtained in that the line spacing and line width are wide and the manufacturing is easy.

As described above, according to the present embodiment, a distributed coupling type directional coupler having a high coupling degree by adding a lumped constant capacitance to the central portion of the parallel coupling line, is easy to manufacture and has high productivity. Can be realized.

(Second Embodiment) The second and third embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a plan view of a distributed coupling type directional coupler according to the second and third embodiments of the present invention. Figure 2
2A and 2B is different from the configuration of FIG. 1 in that a capacitance is added to the ground from each terminal. In FIG. 2A, the lumped constant capacitance 24 is used, and
In (b), the distributed constant capacity 26 is used.

As described above, by adding a capacitance from each terminal to the ground, impedance matching can be achieved, and there is little reflection at the target frequency and good isolation is achieved. Can be realized.

Further, since the capacitance is added to the ground from both ends of the microstrip line, the line length is shortened when the electrical length of the microstrip line is the same, and therefore, in the present embodiment as well. The line length of the coupled line can be shortened due to the added capacitance for impedance matching, and the phase difference of the output signals is 90%.
It is possible to realize a distributed-coupling type directional coupler having a degree of °.

Although the microstrip line distributed coupling type directional coupler is shown in the first embodiment and the second and third embodiments, the strip line distributed coupling type directional coupler also has a line width, It goes without saying that it is possible to increase the track spacing.

[0024]

As described above, according to the present invention, a lumped constant capacitance is added to the central portion of the parallel coupled line, so that the degree of coupling is high and the line spacing and the line width can be widened.
By adding the capacitance from one input / output terminal to the ground, it is possible to realize a distributed coupling type directional coupler with a good matching state and a short line length and excellent productivity.

[Brief description of drawings]

FIG. 1 is a plan view of a distributed coupling type directional coupler according to a first embodiment of the present invention.

2A is a plan view of a distributed coupling type directional coupler according to a second embodiment of the present invention. FIG. 2B is a plan view of a distributed coupling type directional coupler according to a third embodiment of the present invention.

FIG. 3 is a plan view of a conventional distributed coupling type directional coupler.

[Explanation of symbols]

 11 input terminal 12 output terminal 13 isolation terminal 14 lumped constant capacitance 24 lumped constant capacitance 25 earth 26 distributed constant capacitance

Claims (5)

[Claims] 1. A distributed coupling type directional coupler comprising two parallel coupled lines, wherein a lumped constant capacitance is added to the central portion of the coupled lines. 2. The distributed coupling type directional coupler according to claim 1, wherein a lumped constant capacitance is added to the ground from four input / output terminals of the distributed coupling type directional coupler. 3. The distributed coupling type directional coupler according to claim 1, wherein distributed constant capacitance is added to the ground from four input / output terminals of the distributed coupling type directional coupler. 4. The line length of the coupled line is λ at the center frequency.
The distributed coupling type directional coupler according to claim 2, wherein the directional coupler is shorter than _g / 4. 5. A distributed coupling type directional coupler according to claim 1, 2, 3, or 4, wherein the coupling line is a microstrip line.