JPH05136597A - Signal leakage preventing structure of microwave circuit - Google Patents

Abstract

PURPOSE:To realize a signal leakage preventing structure of a microwave circuit which functions as a reactance attenuator large enough in attenuation quantity, where the signal leakage preventing structure prevents spurious microwaves from leaking out from a microwave circuit such as an oscillation circuit or the like provided onto the surface of a dielectric board. CONSTITUTION:Through-holes 2, which electrically connects a grounding conductor 1 formed on the surface of a dielectric board 3 to another grounding conductor 4 formed on the rear side penetrating the dielectric board 3, are provided surrounding a microwave circuit provided onto the surface of the dielectric board 3 at a regular interval a. so as to prevent spurious microwaves from leaking out from the microwave circuit, and the through-holes 2 are elliptical in cross section and vertically provided to one side of the board 3 in a line at a regular interval a1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit provided on the surface of a dielectric substrate, and more particularly to preventing unnecessary microwave leakage from the microwave circuit such as an oscillation circuit provided on the surface of the substrate to the outside. The present invention relates to a structure for preventing signal leakage of a microwave circuit.

[0002]

2. Description of the Related Art A conventional signal leakage preventing structure for a microwave circuit is shown in FIGS. In the figure, 1 is a ground conductor on the front surface of the substrate, and 4 is a ground conductor on the back surface of the substrate. Reference numeral 2 is a through hole that penetrates through the substrate and connects the ground conductors 1 and 4 on the front and back surfaces, and 3 is a dielectric substrate for forming a microwave circuit such as an oscillation circuit on the surface of the substrate. FIG. 5B is a perspective view of the metal casing 5 that covers the upper side of the microwave circuit on the surface of the substrate to prevent the microwave from leaking to the outside. The grounding conductor 1 on the substrate surface, which is provided with the through holes 2 arranged in a line in the perspective view of FIG. 4A, is arranged so as to surround the microwave circuit (not shown) on the substrate surface. Of FIG.
(A) is a cross-sectional view of a conventional leakage prevention structure, in which the through hole 2 is a dielectric substrate 3 sandwiched between upper and lower casings 5 and 6.
Conduct electrical connection to the ground conductors 1 and 4 on the front and back sides of. The distance a ₁ between the through holes 2 in the perspective view of FIG. 4A is selected to be half wavelength λg / 2 or less with respect to the fundamental frequency λg of the microwave signal of the circuit. With this structure, a wall of the ground conductor is approximately formed for unnecessary microwave signals traveling in the housings 5 and 6, and the microwave is prevented from leaking to the outside of the circuit board 3. It had a structure to prevent it.

[0003]

When the dielectric substrate 3 of FIGS. 4 and 5 is viewed as the reactance attenuator shown in FIG. 2, a in FIG. 2 is the width of the constricted portion of the attenuator. L is the length of the waist. If the distance between the through holes 2 of the conventional structure is a ₁ as shown in FIG. 4B and its diameter is φ, the width a and the length of the constricted part of the reactance attenuator in FIG.
The value corresponding to L is approximated as a = a ₁ −φ, L = φ.
The cavity of the reactance attenuator shown in FIG. 2 corresponds to the dielectric substrate 3. Therefore, when the conventional structure is viewed as a reactance attenuator, the value of the constriction length L is only the value of the diameter φ of the through hole 2, and a sufficient attenuation amount can be obtained for the attenuator. There was a problem that it did not exist. An object of the present invention is to realize a structure for preventing signal leakage of a microwave circuit that can obtain a sufficient amount of attenuation when the structure is viewed as a reactance attenuator.

[0004]

In order to achieve this object, the structure for preventing leakage of the present invention eliminates the fixed idea that the conventional through hole 2 is circular, and the principle diagram (A) of FIG.
In the perspective view, as shown in (B), the through hole 2 for penetrating the substrate 3 to establish continuity between the ground conductor 1 on the front surface of the dielectric substrate 3 and the ground conductor 4 on the back surface (not shown) has a cross section of An oval hole with width w and length L ₁ . Then, the through hole 2 whose cross section is processed into an ellipse is provided in a row at a distance a ₁ perpendicularly to one side of the substrate 3, and the value of the constriction length L when viewed as a reactance attenuator in FIG. Is designed to be large enough.

[0005]

According to the present invention, referring to FIG. 1, the cross-sectional shape of the through hole 2 for achieving the conduction between the ground conductor 1 on the front surface of the dielectric substrate 3 and the ground conductor 4 on the back surface (not shown) is as follows. width
w, length L ₁ oval, with through holes 2 spaced a ₁
Since it has a structure in which a required number of columns are provided vertically on one side of the substrate 3, when viewed as the reactance attenuator of Fig. 2, the width a and the length L of the constricted part are a = a _1- w
, L = L ₁ , and the value of length L can be made large enough,
It is possible to obtain the required amount of attenuation.

[0006]

1 is a diagram showing the signal leakage prevention structure of a microwave circuit according to a first embodiment of the present invention without changing the principle of FIG. 1, and its cross section is an ellipse having a width w and a length L _1. The processed through holes 2 are provided in a row in parallel with the interval a ₁ selected to be equal to or less than the half wavelength λg / 2 with respect to the fundamental frequency λg of the microwave of the circuit. The through hole 2 is provided so as to be perpendicular to the side of the ground conductor 1 on the surface of the substrate 3. When the dielectric substrate 3 of the first embodiment is viewed as the reactance attenuator of FIG. 2, the values of the width a and the length L of the constricted portion are
a = a ₁ −w and L = L ₁ .

FIG. 3 shows the structure of the second embodiment of the present invention.
You Unlike the structure of the embodiment shown in FIG.
Connect the through hole 2 to one side of the ground conductor 1 on the surface of the substrate 3.
So that they are parallel to each other.₂With two rows in a straight line
The first row through hole 2₁And the 2nd row through hole
2₂Like to fill the space between through holes in other rows
Is composed of. In this second embodiment, the through hole 2
_1,2₂2 rows of a₂Of the reactance attenuator in Fig. 2.
Corresponding to the width a of the fin, two rows of through holes 2_1,2 ₂The weight of
Compound L₂Is equivalent to the constriction length L of the reactance attenuator
To do. In order to completely prevent leakage, the first embodiment
In both cases, the casing is similar to the conventional structure.
When the bodies 5 and 6 are covered from above and below the circuit board, the through holes
Make sure that 2 is completely covered, as shown in Figure 5 (A).

[0008]

As described above, according to the present invention, it is possible to more reliably prevent the microwave signal of the microwave circuit provided on the dielectric substrate from leaking to the outside of the circuit. Therefore, the effect of improving the spurious characteristic of the wireless communication device using the microwave circuit provided on the dielectric substrate can be obtained.

[Brief description of drawings]

FIG. 1 is a principle diagram showing a basic configuration of a signal leakage prevention structure of a microwave circuit according to the present invention.

FIG. 2 is a structural diagram of a reactance attenuator for explaining the operation of a signal leakage prevention structure of a microwave circuit according to the present invention.

FIG. 3 is a diagram showing a signal leakage prevention structure of a microwave circuit according to a second embodiment of the present invention.

FIG. 4 is a perspective view and a top view of a conventional structure for preventing signal leakage of a microwave circuit.

FIG. 5 is a cross-sectional view of a conventional signal leakage prevention structure of a microwave circuit and a perspective view of a covered housing.

[Explanation of symbols]

Reference numeral 1 is a ground conductor on the front surface of the substrate, 2 is a through hole, 3 is a dielectric substrate, 4 is a ground conductor on the back surface of the substrate, 5 is a housing above the ground conductor 1, and 6 is a housing below the ground conductor 4. ..

Claims (2)

[Claims] 1. A microwave circuit provided on the surface of a dielectric substrate (3) is provided with a ground conductor (1) on the same surface and a ground conductor (4) on the back surface.
And through holes for electrical continuity through the board (3)
In a structure in which a plurality of (2) are provided at regular intervals (a ₁ ) and surrounded to prevent unnecessary microwaves from leaking from the microwave circuit to the outside, the through hole (2) is A structure for preventing signal leakage of a microwave circuit, characterized in that the holes are formed in an oval shape and the through holes are provided in a line at a constant interval (a ₁ ) perpendicularly to one side of the substrate (3). 2. The oval through holes (2) are provided in two rows (2 _1, 2 ₂ ) horizontally on one side of the substrate (3) at regular intervals (a ₂ ). The through hole (2 ₁ ) and the through hole (2 ₂ ) in the second row are arranged such that the centers of the through holes are located between the through holes in the other rows. Microwave circuit signal leakage prevention structure.