JPH0834367B2 - Branch line directional coupler - Google Patents

Description

TECHNICAL FIELD The present invention relates to a branch line directional coupler often used in a microwave band.

[Conventional technology]

FIG. 3 is a view of a conventional branch line directional coupler described in P203 of “Revision Microwave Circuit” (published by Corona Publishing Co., Ltd.), and FIG. 4 is a perspective view showing the A1-A2 cross section,
(1) and (2) are inner conductors, (3) and (4) are branch inner conductors,
(5) is a dielectric substrate, (6) is an outer conductor, and P1 to P4 are terminals.

Also, the inner conductors (1) and (2) and the branch inner conductor (3)
(4) are arranged in parallel on the same branch substrate at intervals of 1/4 wavelength.

Next, the operation will be described. When a wave is excited at the terminal P1, the wave propagating through the inner conductor (1) is coupled with the inner conductor (2) at the branch inner conductors (3) and (4).

If the lengths of the branch inner conductors (3) and (4) and the spacing between the two are selected to be 1/4 wavelength, the waves propagating to the terminal P4 through the branch inner conductors (3) and (4) have opposite phases. The combined wave is canceled at the terminal P3.

[Problems to be solved by the invention]

In the conventional branch line directional coupler configured as described above, when a waveguide mode other than the originally propagating TEM mode is generated, the electric field distribution becomes as shown in FIG. When the cutoff frequency is within the used band, waveguide mode resonance occurs and the passage and coupling characteristics deteriorate.

The present invention has been made in order to solve the above-mentioned problems, and an object thereof is to remove resonance due to a waveguide mode out of the band and obtain favorable pass-through and coupling characteristics.

[Means for solving problems]

The branch line directional coupler according to the present invention is provided with a rectangular outer conductor, a dielectric substrate held on both sides of the outer conductor, and both main surfaces of the dielectric substrate, which are arranged to face each other. First and second inner conductors, and first and second branch inner conductors provided on both main surfaces of the dielectric substrate and connecting the first and second inner conductors with a space therebetween. An upper surface of the outer conductor at a position surrounded by the first and second inner conductors and the first and second branched inner conductors, the suspended structure having a And a conducting rod connected to the lower surface.

[Action]

In the present invention, by providing a conductor rod for connecting the upper and lower outer conductors in a space surrounded by the inner conductor and the branch inner conductor, the waveguide mode is increased and the cutoff frequency is increased, and the waveguide is generated in the used band. Modal resonance can be eliminated.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing a branch line directional coupler, and FIG. 2 is a sectional view taken along the line A1-A2 in FIG. A line state in which inner conductors of the same shape are provided substantially symmetrically, for example, a case where a line form generally called a suspended strip line is used will be described.

The line type as shown in FIG. 1 or FIG. 2 is higher or lower than the one in which the inner conductor is provided only on the upper surface of the dielectric substrate, which causes the waveguide mode resonance on the dielectric substrate. There is an advantage that the imbalance of the electric field distribution in the direction is prevented.

In FIGS. 1 and 2, (1) and (2) are first and second inner conductors made of strip conductors, and (3), (3), and (4).
(4) is a strip conductor and is a first and second inner branch conductor connected to the first and second inner conductors (1) and (2),
(5) is a dielectric substrate, (6) is an outer conductor that holds the dielectric substrate (5), and (7) is conductive that has come into contact with and penetrates the dielectric substrate (5) as is apparent from FIG. The conducting rod (7) is surrounded by the first and second inner conductors (1) and (2) and the first and second branch inner conductors (3), (3), (4) and (4). The outer conductor (6) is connected to the upper and lower surfaces of the outer conductor (6) by penetrating the dielectric substrate (5).

In the branch line directional coupler of the present invention, when the waveguide mode is generated, the electric field distribution of the waveguide mode is as shown in FIG. 6 because the outer conductor is conducted by the conducting rod (7). The cutoff frequency can be increased as compared with the conventional branch line directional coupler. As a result, the resonance of the waveguide mode is removed out of the band, and good passage and coupling characteristics are obtained.

In the above embodiment, the two branch inner conductors (3),
In the branch line directional coupler having three or more branch inner conductors, which is provided with (4), even if two or more conducting rods are provided in the space surrounded by each inner conductor and branch inner conductor. Has the same effect. FIG. 7 shows an example of a branch line directional coupler having three branch inner conductors.

〔The invention's effect〕

As described above, according to the present invention, it is possible to prevent the deterioration of the pass characteristic and the coupling characteristic of the coupler by increasing the cutoff frequency of the waveguide mode and removing the waveguide mode resonance generated in the used band. At the same time, the conducting rod is in contact with and penetrates the dielectric substrate, and is connected to the upper surface and the lower surface of the outer conductor at a position surrounded by the first and second inner conductors and the first and second branch inner conductors. Since the conducting rod is provided, it is possible to suppress the generation of the waveguide mode due to the imbalance of the electric field distribution in the vertical direction of the dielectric substrate due to the thermal deformation of the dielectric substrate.

[Brief description of drawings]

FIG. 1 is a diagram showing a branch line directional coupler according to an embodiment of the present invention, FIG. 2 is a sectional perspective view, FIG. 3 is a diagram showing a conventional directional coupler, and FIG. Perspective view, fifth
6 and 6 are diagrams showing the electric field distribution in the waveguide mode, and FIG. 7 is a diagram showing another embodiment. In the figure, (1) and (2) are inner conductors, (3) and (4) are branched inner conductors, (5) is a dielectric substrate, (6) is an outer conductor, and (7) is a conducting rod. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoji Isota 5-1, 1-1 Ofuna, Kamakura-shi, Kanagawa Mitsubishi Electric Corporation, Information & Electronics Laboratory (72) Inventor Moriyasu Miyazaki 5-chome, Ofuna, Kamakura-shi, Kanagawa No. 1 Mitsubishi Electric Co., Ltd. Information Technology Laboratory (56) Reference JP 61-184901 (JP, A) JP 58-194403 (JP, A) JP 53-68890 (JP, A) JP Showa 38-22953 (JP, B1)

Claims (1)

[Claims] 1. A rectangular outer conductor, a dielectric substrate held on both sides of the outer conductor, and first and second oppositely arranged respective main surfaces of the dielectric substrate. A branch having a suspended structure having an inner conductor and first and second branch inner conductors respectively provided on both main surfaces of the dielectric substrate and connecting the first and second inner conductors with a space therebetween. In the line-directional coupler, the dielectric conductor is contacted and penetrated, and the outer conductor is placed at a position surrounded by the first and second inner conductors and the first and second branched inner conductors. A branch line directional coupler comprising a conducting rod connected to an upper surface and a lower surface.