JP2895669B2 - Directional coupler - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention mainly relates to a VHF band,
The present invention relates to a directional coupler used in the UHF band and the microwave band.

[0002]

2. Description of the Related Art Conventionally, there has been an apparatus of this type as shown in FIG. FIG. YAMAMOTO,
T. AZAKAMI and K. ITAKURA,
“Coupled Nonuniform Trans
Mission Line and Its Appl
ications ”, IEEE Trans. on M
TT, vol. MTT-15, no. 4, pp. 220
-231, Apr. 191, 1 is a center conductor, 2 is a ground conductor, 3 is a common ground conductor, 4
Is a coupling slit, 5 is an input terminal, 6 is an output terminal, 7 is a coupling terminal, 8 is an isolation terminal, 10 is a main line, 1
1 is a sub track. FIG. 9 is a sectional view of the directional coupler. Here, the ground conductors 2a and 2b and the common ground conductor 3
Are electrically connected and at the same potential. The center conductor 1a, the ground conductor 2a and the common ground conductor 3 are
And a center conductor 1b and a ground conductor 2
b and the common ground conductor 3 form a triplate line of the sub line 11. The coupling slit 4 is a hole formed in the common ground conductor 3 along the length direction of the center conductors 1a and 1b.

Next, the operation will be described. The main line 10 and the sub-line 11 are shielded from each other by the common ground conductor 3, but are electromagnetically coupled at a portion of the coupling slit 4 formed in the common ground conductor 3 to form a coupled line. The signal applied to the input terminal 5 propagates along the main line 10 to the output terminal 6 along the center conductor 1a. A part of the electromagnetic field of the signal propagating through the main line 10 leaks to the back side of the common ground conductor 3 through the coupling slit 4 formed in the common ground conductor 3 and is coupled to the central conductor 1b by electromagnetic induction. 1
Propagate 1. At this time, since only the electromagnetic field component propagating in the opposite direction to the signal propagating through the main line 10 is induced in the sub-line 11, the coupled signal is output only to the coupling terminal 7 and appears at the isolation terminal 8. Absent. Conversely, when a signal is applied from the output terminal 6 side, the signal coupled to the sub-line 11 appears on the isolation terminal 8 side and does not appear on the coupling terminal 7 side. Therefore, the input terminal 5 is connected to the coupling terminal 7.
Since only the signal propagating from the input terminal 6 to the output terminal 6 appears in combination, it operates as a directional coupler. In such a slit-coupled directional coupler, the center conductor 1a
A common ground conductor 3 is provided between the ground conductor 1b and the main ground line 10 and the sub-line 11 are coupled by a coupling slit 4 opened in the common ground conductor 3. Therefore, the common ground conductor 3 is provided between the two center conductors. In this case, a directional coupler having a smaller coupling degree than in the case where there is no coupling is obtained, and the coupling degree can be changed by changing the width of the coupling slit 4.

[0004]

Since the conventional directional coupler is constructed as described above, the sectional structure of the line suddenly changes at both ends of the coupling slit and becomes discontinuous. Due to the disturbance of the electromagnetic field, an electromagnetic field component propagating in the same direction as the signal on the main line is guided to the sub line and output to the isolation terminal, resulting in a problem that the directivity is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to obtain a directional coupler having high directivity.

[0006]

SUMMARY OF THE INVENTION A directional connection according to the present invention is provided.
The coupler consists of a center conductor and an outer conductor.
A main line with a central conductor and an outer conductor
And the sub-line with isolation terminals are placed in parallel
And a thread for coupling to the common part of the outer conductor of the main line and sub line.
Direction consisting of a coupling line connected by providing a slot-shaped coupling hole
In the sexual coupler, the slit-shaped coupling hole is provided.
Caused by discontinuous structure due to the same direction as main line signal
The phase is 180 degrees with the same amplitude as the signal propagating through the sub-line
Differently, a signal that propagates along the sub-line in the same direction as the signal on the main line
In all or some sections of the coupled line
In the area between the center conductor of the main line and the center conductor of the sub-line.
Providing a dielectric in the path of the magnetic field distribution for the main line and sub line
The difference between the phase speeds of even mode and odd mode
And the generated signal is converted to the slit-shaped coupling hole.
Superimposed on the signal generated by the discontinuous structure due to the provision
Thus, the output to the isolation terminal is reduced .

[0007]

According to the invention, the center conductor and the outer conductor are provided.
Main line with input and output terminals, center conductor and outer conductor
Sub-portion consisting of a body and having a coupling terminal and an isolation terminal
Lines are placed in parallel and the outer conductors of the main line and sub-line are shared.
A slit-shaped coupling hole is provided in the
In a directional coupler consisting of a combined line,
Mainly generated by the discontinuous structure due to the
Signals propagating in the sub-line in the same direction as the line signal have the same amplitude
The phase differs 180 degrees, and the
The signal propagating through the line is transmitted to all or
Is the center conductor of the main line and the center of the sub line in some sections
By providing a dielectric in the path of the electromagnetic field distribution in the area between conductors,
Even and odd mode phase velocities for line and subline
Generated by making a difference
Discontinuous structure with slit-shaped coupling holes
It is superimposed on the generated signal and cancels out.
Output to the main line and sub-line as described above.
Induces a difference in the phase velocity between even and odd modes
Directivity connection with high directivity by a simple method of providing an electrical body
Implement a combiner.

[0008]

【Example】

Embodiment 1 FIG. FIG. 1 is a structural view showing an embodiment of a directional coupler according to the present invention, and FIG. 2 is a sectional view showing a sectional structure thereof.
In the figure, 1 to 8, 10 and 11 are the same as those shown in FIG. 8, and 9 is a dielectric. Dielectrics 9a and 9b
Are mounted on the common ground conductor 3 side of the center conductors 1a and 1b in close contact with the center conductors 1a and 1b, respectively.
In this embodiment, a rectangular hole is formed in a common outer conductor as a joint.

Next, the operation will be described. The electric field distributions of the odd mode and the even mode in the coupling line portion of the directional coupler of the slit coupling type shown in FIG. 1 are as shown in FIGS. 3 and 4, respectively. As can be seen from these figures, in such a structure, the electric field passing through the dielectrics 9a and 9b is larger in the odd mode than in the even mode. Phase velocity becomes slower. In a directional coupler that does not use a normal coupling slit, when there is a difference between the phase speeds of the odd mode and the even mode, an electromagnetic field component propagating in the same direction as the signal of the main line is induced on the sub-line. It is known that the directionality is deteriorated. As described above, the connection slit ends are disconnected.
Signal generated by the connection and the
The difference between the odd and even mode phase velocities
The generated signals are all in the same direction as the main line signals.
It propagates through the line and appears at the isolation terminal 8.
Oh Ru. Therefore, it is caused by discontinuity at the end of the coupling slit.
Difference between the odd and even mode phase velocities
Signal amplitudes are equal and 180 degrees out of phase
By selecting the dimensions of the dielectrics 9a and 9b so that
So that these two signals can cancel each other out,
A directional coupler having high directivity can be obtained.

In the first embodiment, the position of the dielectric material is not only fixed in close contact with the center conductors 1a and 1b, but also acts unevenly on the electric fields of the odd mode and the even mode to cause the odd mode and the even mode. May be inserted at a position where a difference occurs in the phase velocities.

Embodiment 2 FIG. 5 is a structural view showing another embodiment of the present invention, in which a coaxial line is used to form a slit-coupled directional coupler having a rectangular hole in a common outer conductor as a coupling portion. FIG. 6 is a diagram showing a cross-sectional structure of the directional coupler of FIG. Here, the dielectric 9 is inserted into the coupling slit 4. In the drawing, reference numerals 1 to 4 and 9 are the same as those shown in FIG.

The embodiment of FIG. 5 has the same operation principle and advantages as those of FIG. 1, and has a small size because a dielectric is inserted at a place where the difference between the electric field distributions of the even mode and the odd mode is largest. However, there is an advantage that the difference between the phase velocities of the odd mode and the even mode can be increased even if the dielectric material of (1) is used, and the directional coupler can be miniaturized by miniaturizing the inserted dielectric material. In addition, since it is configured using a coaxial line, the center conductors 1a, 1b
Are completely surrounded by the ground conductors 2 and 3, respectively, so that there is an advantage that there is no unnecessary interference between the main line 10 and the sub line 11. Further, since the center conductors 1a and 1b have a circular cross section, there is an advantage that there is no place where an electric field is concentrated and that a large power can be endured.

Embodiment 3 FIG. 7 is a structural view showing still another embodiment of the present invention. In the first and second embodiments, the dielectric is inserted over the entire length of the coupling slit.
As described above, the same effect can be obtained by inserting only into a part of the coupling slit which acts non-uniformly on the electric fields of the odd mode and the even mode to cause a difference in the phase velocity between the odd mode and the even mode.

[0014]

As described above, according to the present invention, the slip
Generated by the discontinuous structure due to the
Signal and amplitude propagating in the sub-line in the same direction as the main line signal
Are equal and 180 degrees out of phase, in the same direction as the main line signal
The signal propagating through the sub-line to all or
Is the center conductor of the main line and the center of the sub line in some sections
By providing a dielectric in the path of the electromagnetic field distribution in the area between conductors,
Even and odd mode phase velocities for line and subline
Generated by making a difference
Discontinuous structure with slit-shaped coupling holes
As the signal is superimposed on the generated signal and cancels out, the main
Even and odd mode phase velocities for line and subline
There is an effect that a directional coupler with high directivity can be obtained by a simple method of providing a dielectric material that makes a difference .

[Brief description of the drawings]

FIG. 1 is a structural diagram showing Embodiment 1 of the present invention.

FIG. 2 is a sectional view showing Embodiment 1 of the present invention.

FIG. 3 is an explanatory diagram showing an electric field distribution in an odd mode in Embodiment 1 of the present invention.

FIG. 4 is an explanatory diagram showing an even mode electric field distribution in Embodiment 1 of the present invention.

FIG. 5 is a structural diagram showing a second embodiment of the present invention.

FIG. 6 is a sectional view showing a second embodiment of the present invention.

FIG. 7 is a structural diagram showing a third embodiment of the present invention.

FIG. 8 is a structural diagram showing a conventional directional coupler.

FIG. 9 is a cross-sectional view illustrating a conventional directional coupler.

[Explanation of symbols]

 Reference Signs List 1 center conductor 2 ground conductor 3 common ground conductor 4 coupling slit 5 input terminal 6 output terminal 7 coupling terminal 8 isolation terminal 9, 9a, 9b dielectric 10 main line 11 sub line

Continuation of the front page (72) Inventor Osamu Ishida 5-1-1, Ofuna, Kamakura-shi Mitsubishi Electric Corporation Electronic Systems Laboratory (56) References JP-A-63-300606 (JP, A) JP-A-64 JP-A-89802 (JP, A) JP-A-62-114302 (JP, A) JP-A-4-321302 (JP, A) JP-A-60-500594 (JP, A)

Claims (1)

(57) [Claims] 1. An input terminal comprising an outer conductor and a center conductor.
A main line with force terminals and a center conductor and outer conductor
Parallel connection terminal and auxiliary line with isolation terminal
Arranged in the main line and the directional coupler comprising a coupling line which is coupled to provide a slit-shaped coupling hole for coupling to a common portion of the outer conductor of the sub-line is provided with the slit-shaped coupling hole
And the main line signal generated by the discontinuous structure
The signal has the same amplitude as the signal propagating through the sub-line in the same direction and the phase is 1
80 becomes Dokoto, to propagate the sub-line to signal the same direction of the main line
Signal in all or a part of the above coupling line section
Area between the center conductor of the main line and the center conductor of the sub-line in Japan
With a difference in phase velocity of the even and odd modes is provided a dielectric in the path of the electromagnetic field distribution of the band for the main line and the sub-line <br/> Turkey
And the generated signal is connected to the slit
Signal generated by discontinuous structure due to the presence of a hole
To the output of the isolation terminal.
Directional coupler, characterized in that the reduction.