JPH09298407A - Microstrip line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the passing loss by forming a conductor thin film with a cavity corresponding to the location of a microstrip on the rear side of a microstrip dielectric board and fixing a ground metallic conductor to the conductor thin film. SOLUTION: A part of a rear conductor thin film 5 formed in advance by vapor-deposition or the like on the rear side of a dielectric board 2 where a microstrip 1 is placed on the front and corresponding to the microstrip 1 is exfoliated or removed in advance in the case of forming a pattern of the board. Thus, in the case of soldering or screw-fastening the dielectric board 2 and a ground metallic conductor 4, a cavity layer 3 is formed between the dielectric board 2 and the round metallic conductor 4 corresponding to the board 2. Through the constitution above, even when a dielectric board whose dielectric constant is high is in use, since the dielectric constant of the cavity layer is '1', the combined dielectric constant is nearly '1', the wavelength reduction rate of the circuit is increased, and a transmission loss of the microstrip line is as small as that formed on a dielectric board whose dielectric is nearly '1'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved technique capable of reducing the amount of passage loss in a microstrip line which is a high frequency transmission line constituting a microwave integrated circuit.

[0002]

2. Description of the Related Art A conventional technique for reducing the amount of passage loss in a microstrip line is disclosed in Japanese Utility Model Laid-Open No. 63-14.
Description will be made based on the technique described in Japanese Patent Publication No. 7003.

FIG. 2 is a sectional view showing the structure of an embodiment of a conventional microstrip line. In the figure,
11 is a microstrip which is a high-frequency transmission line, 12
Is a dielectric substrate on which the microstrip 11 is wired, 1
3 is a dielectric substrate 12 on which the microstrip 11 is located
Is a cavity layer formed on the back surface side of the substrate, 14 is a grounding metal conductor for releasing the charge to the ground, and 16 is a spacer for arranging the grounding metal conductor 14 at a constant distance from the back surface of the dielectric substrate 12, A part is chipped off to form the cavity layer 13.

Next, the effect of reducing the amount of passage loss will be described. A cavity layer 13 is provided between a dielectric substrate 12 on which the microstrip 11 is wired and a grounding metal conductor 14 with a spacer 16 interposed therebetween. Utilizing air as part of body 12 reduces dielectric loss.

[0005]

The above-mentioned conventional microstrip line has the following problems.

The first problem is that the shape of the microstrip line becomes thick. The reason is that a spacer is provided between the substrate and the grounding metal conductor in order to secure a cavity under the dielectric substrate.

The second problem is that the conventional method cannot confirm whether or not the cavity under the dielectric substrate can be surely secured. The reason is that it is difficult to set the position of the spacer so that a cavity is just formed under the microstrip because it is hidden by the substrate.

The present invention has been made in view of the above problems of the prior art.
An object of the present invention is to easily reduce the amount of passage loss and make it thin to facilitate the manufacture of a microstrip line which is a high-frequency transmission line constituting a microwave integrated circuit.

[0009]

In order to solve the above problems, the present invention provides a microstrip line, wherein the microstrip is located on the back surface side of a dielectric substrate on which a microstrip which is a high frequency transmission line is wired. It is characterized in that a conductor thin film having a cavity lacking a corresponding portion is fixed, and a grounding metal conductor is fixed to the conductor thin film, whereby a gap between the dielectric substrate and the grounding metal conductor facing it is fixed. Even if a dielectric substrate with a high permittivity is used, the combined permittivity when substances with different permittivities are connected in series will be εε '/ (ε + ε') even if a dielectric substrate with a high permittivity is used. The dielectric constant of the cavity layer ε = 1
Considering the above, the combined permittivity is almost 1 regardless of the permittivity of the dielectric substrate. Therefore, according to the present technology, the wavelength shortening rate of the circuit can be increased, so that the electrical length per unit length is shortened, and thus the passage loss of the circuit can be reduced.

In addition, as a means for forming a cavity layer provided between the dielectric substrate and the grounding metal conductor facing the dielectric substrate, a conductor on the back surface of the dielectric substrate on which the microstrip is located without using a spacer. By eliminating the thin film, the thickness of the cavity layer was only a few μm, making it possible to reduce the shape of the microstrip line.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of the present invention, a microstrip line has a cavity in which a corresponding portion where the microstrip is located is lacked on the back surface of a dielectric substrate on which the microstrip which is a high frequency transmission line is wired. The conductor thin film which it has is fixed, and also the metal conductor for grounding is fixed to the conductor thin film.

[0012]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing the structure of an embodiment of the microstrip line of the present invention. In the figure, 1 is a microstrip, which is a high-frequency transmission line,
2 is a dielectric substrate on which the microstrip 1 is wired, 3
Is a cavity layer formed on the back surface side of the dielectric substrate 2 on which the microstrip 1 is located, and the corresponding portion of the back surface conductor thin film 5 is peeled or removed in advance when patterning the substrate. Reference numeral 4 denotes a grounding metal conductor that allows the electrostatic charge to escape to the ground, and 5 denotes a back surface conductor thin film for facilitating adhesion of the grounding metal conductor 4 to the back surface of the dielectric substrate 2, which is formed in advance by vapor deposition or the like when forming a pattern on the substrate. To be done.

Next, the operation of the above structure will be described. The back surface conductor thin film 5 of the dielectric substrate 2 on which the microstrip 1 is located has been peeled or removed in advance when the pattern of the substrate is formed. When soldering and the metal conductor 5 for grounding or screwing,
The cavity layer 3 is formed between the dielectric substrate 2 and the grounding metal conductor 5 facing it.

According to this structure, since the combined permittivity when substances having different permittivities are connected in series can be represented by εε '/ (ε-10ε'), a dielectric substrate having a high permittivity. Even if is used, the combined permittivity is almost 1 when the permittivity ε of the cavity layer is taken into consideration. Therefore, according to the present technology, the wavelength shortening rate of the circuit can be increased, so that the electrical length per unit length is shortened, and the microstrip line is the same as that formed on a dielectric substrate having a dielectric constant of about 1. Only a small amount of passage loss is required.

Also, as a means for forming a cavity layer provided between the dielectric substrate and the grounding metal conductor facing the dielectric substrate, a conductor thin film on the back surface of the dielectric substrate on which the microstrip is located without using a spacer. Since the cavity is removed, the cavity layer can be formed with a thickness of only a few μm.

Further, as a means for forming the cavity layer, a method of eliminating the conductive thin film on the back surface of the dielectric substrate was adopted instead of the spacer, which is difficult to set the position, so that the position setting became unnecessary.

[0017]

According to the structure of the present invention, first, the passage loss can be reduced even if a dielectric substrate having a high dielectric constant is used. It is also possible to make the shape of the microstrip line thin. Further, it is easy to surely secure the cavity layer under the dielectric substrate and the production is easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of an embodiment of a microstrip line of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of an example of a conventional microstrip line.

[Explanation of symbols]

 1, 11 Microstrip 2, 12 Dielectric substrate 3, 13 Cavity layer 4, 14 Grounding metal conductor 5 Back conductor thin film 16 Spacer

Claims (2)

[Claims] 1. A dielectric substrate on which a microstrip, which is a high-frequency transmission line, is wired, a conductor thin film having a cavity fixed to the back surface of the dielectric substrate and lacking a corresponding portion where the microstrip is located, A microstrip line comprising a grounding metal conductor fixed to a conductor thin film. 2. A cavity lacking a corresponding portion where a microstrip of a conductive thin film fixed to the back surface side of the dielectric substrate is located is formed in advance when forming a pattern on the dielectric substrate. Item 1. The microstrip line according to Item 1.