JPS60251702A - Directional coupler - Google Patents

Abstract

PURPOSE:To increase the required size of a finger to a desired coupling amount by providing a directional coupler on a base constituted with two overlapped dielectric bases and making the thickness of the base of the finger thicker than that of the other part. CONSTITUTION:The dielectric base is constituted by overlapping the 1st dielectric base 6 and the 2nd dielectric base 7, and a terminal microstrip line 2 and the finger part 3 are provided on the 1st dielectric base 6. Conductor films 8, 9 are provided to the contact face between the 1st and 2nd dielectric bases 6, 7 except the contact face below the finger part 3 and each conductor film is connected to a grounding metallic film 10 formed to the lower face of the 2nd dielectric base 7. Through the constitution above, the thickness of the base constituting the finger is made thicker than the thickness of the base constituting the terminal microstrip line and the width of the finger and the interval of the fingers required to obtain a desired coupling amount are increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a directional coupler, and more particularly to a directional coupler constructed on a dielectric substrate and used for distributing microwave power.

[Prior art]

FIG. 1 is a perspective view showing a conventional directional coupler. In the figure, (1) is a dielectric substrate, (2) is a terminal microstrip line, and (3) is a finger.
), (4) is the back metal film, and (5) is the gold wire.

Terminal microstrip line (2), finger (
3) The eight-sided metal film (4) is formed by providing a metal film on the dielectric substrate (1) by vapor deposition, plating, plating, or the like.

FIG. 2 is a sectional view taken along line AA' in FIG. In FIG. 2, the same reference numerals as in FIG. 1 indicate the same parts, W is the finger width, S is the spacing between fingers, and h is the substrate thickness. The coupling amount as a directional coupler is W/h.

Since it is determined as a function of S/h, in the conventional structure shown in FIG. The values of W and S were also determined. For example, a coupler with a coupling amount of 3 dB is
When designing with the structure shown in the figure, h = o, and when using a 6 mm alumina substrate as the dielectric base & fi+, W = 50.
pm, S=about 50 pm, and h=9.
In the case of 3 mm, W=25 μn and 5=25 μm.

As described above, in the conventional structure, as the thickness of the dielectric substrate (1) becomes thinner, the dimensions of W and S become smaller, requiring microfabrication, and due to constraints on machining accuracy, the amount of coupling cannot be adjusted to the desired value. The disadvantage was that it was difficult to do so.

[Overview of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above. In this invention, a directional coupler is constructed on a substrate made by stacking two dielectric substrates, and a finger is constructed. The finger width W1 and the distance Hs between the fingers were increased by increasing the substrate thickness at the portion where the terminal microstrip line is formed compared to the substrate thickness at the portion constituting the terminal microstrip line.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view showing the downstream side of this invention;
The figure is a perspective view showing a method of assembling the directional coupler shown in FIG. 3, and in these figures, the same reference numerals as in FIG. 1 indicate the same parts. However, the numbers for the fingers and gold wires are omitted. (6) is the first dielectric substrate, (7) is the second
dielectric base &, (81 is the first metal film, (9) is the second metal film, (10 is the grounding metal film, 09 is the through hole drilled in the second dielectric substrate (7) It is.

FIG. 5 is a sectional view taken along the A-A' section of FIG.
The same reference numerals as in FIGS. 2, 3, and 4 indicate the same or corresponding parts.

The first metal film (8) and the second metal film (9) shall be fixed by soldering, etc., and the second metal group (9) and the grounding metal film shall be connected to the through hole α℃. Electrical connection is made by providing metal. Therefore, as is clear from FIG. 4 and FIG. In the part where the second metal film (9) is present in the upper plane of the body substrate (7), the surface of the first metal film (8) is at ground potential, and the first metal film (8) and the second metal film (8) are connected to each other. In the part where the metal film (9) is not present, that is, in the lower part of the finger, the surface of the grounding metal film αO is at the ground potential.

That is, in the structures shown in FIGS. 3, 4, and 5, the substrate thickness of the portion constituting the terminal microstrip line (2) is the thickness of the first dielectric substrate (6), and the thickness of the finger ( 3) is the sum of the thickness of the first dielectric substrate (6) and the thickness of the second dielectric substrate (7).

Therefore, in the directional coupler of the present invention, the finger width W1 and the spacing S between the fingers can be increased, and microfabrication is not required.

Note that although the case of a Lange type directional coupler has been described above, the present invention is not limited to this, and can also be applied to a combline coupler or the like.

Further, the through hole 0 may be filled with metal.

〔Effect of the invention〕

As described above, according to the present invention, the ground potential for the portion of the terminal microstrip line that transmits microwave power is configured on the lower surface of the first dielectric substrate, and the microwave power is mutually coupled between the microstrip lines. Since the ground potential for the mutually coupled portions is formed on the lower surface of the substrate in which the first dielectric substrate and the second dielectric substrate are stacked, there is no need for microfabrication of the mutually coupled portions.

[Brief explanation of drawings]

1 is a perspective view showing a conventional directional coupler, FIG. 2 is a sectional view of FIG. 1, and FIG. 3 is a perspective view showing an embodiment of the present invention. Figure A4 is a perspective view showing a method of assembling the directional coupler shown in Figure 3, and Figure 5 is a sectional view of Figure 3. (2)...terminal microstrip line, (3
)...Finger, (5)...Gold wire, (6)...
・Dielectric substrate of nest 1, (7)...second dielectric substrate,
(8)...First metal film, (9)...Second metal film, tld...Grounding metal film, 0P...Through hole. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] A plurality of microstrip lines are disposed 1 m above a dielectric substrate, a conductor covering the lower surface of the dielectric substrate is set to a ground potential, and mutual coupling between the plurality of microstrip lines is provided. In the directional coupler configured by forming a portion on the upper surface of the dielectric substrate, the dielectric substrate is configured by overlapping a first dielectric substrate and a second dielectric substrate, and a plurality of dielectric substrates are formed. microstrip lines and their mutually coupled portions are formed on the upper surface of the first dielectric substrate, and the upper surface of the second dielectric substrate is overlapped so as to contact the lower surface of the first dielectric substrate, A conductor film is formed on this contact surface except for the contact surface portion below the mutually coupled portion, and the lower surface of the second dielectric substrate is covered with a ground conductor, and the conductor film is electrically connected to the ground conductor. A directional coupler characterized by comprising means for connecting to.