JPH06334376A - Case body for microwave circuit - Google Patents

Abstract

PURPOSE:To contrive the improvement of the shielding effect of a case body for microwave circuit, which is used at the time of constitution of a microwave circuit, and a reduction in the cost of the case body for microwave circuit. CONSTITUTION:A case body for microwave circuit is constituted into a structure where a plurality of case body side surfaces 12 made in a sheet metal structure are all bent in the inner side of a case body by a prescribed length from one end of each of the side surfaces 12, spaces 122, which are made by bent parts 121 and bent parts, are covered with a flat cover 11, the cover is fixed on the bent parts at a pitch of 1/2 or narrower of a wavelength to be used and at the same time, an earth pattern 141 formed on the surface one side of the surfaces of a circuit board 14 of roughly the same form as that of a space, which is made by the other ends of the plurality of the case body side surfaces 12, and roughly the whole periphery of the case body in the vicinities of the other ends of the side surfaces 12 are connected to each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave circuit housing used for constructing a microwave circuit.

In general, the radio noise interference that interferes with the surrounding equipment by the radio noise generated from the equipment includes radiation noise interference radiated directly from the equipment and conduction noise interference leaking to the outside through the power supply line. As measures against radiated noise interference, it is necessary to consider shielding the housing and cables, but especially when considering the housing, it is necessary to improve the shielding effect and reduce the cost.

[0003]

2. Description of the Related Art FIG. 3 is a structural explanatory view (in the case of a cutting housing) of a conventional example, (a) is a perspective view of a microwave circuit housing, and (b) is a microwave circuit housing.
FIG. 7A is a sectional view taken along line XX ′ in (a). Further, FIG. 4 is another structural explanatory view of the conventional example (in the case of a sheet metal housing), (a) is a perspective view of a microwave circuit housing, and (b) is a cross-sectional view taken along line XX ′ of (a). .

The following is a description of FIGS. 3 and 4. First, for the cutting housing, for example, a block of aluminum is shaved to make a housing 22 as shown in FIG. 3 (a) -and a lid 21 as shown in FIG. 3 (a)-.
The housing thickness 221 is as large as 4 mm, for example.
Then, as shown in FIG. 3B, the microwave circuit board (printed board) 2 on which the component 26 is mounted on the bottom surface of the inside 222 of the housing.
Place 4 and fix it to the housing with screws. Further, a coaxial connector 23 is attached to the side surface of the housing, and after connecting with a terminal on the circuit board, a lid is attached to the housing with a screw 25. Then, the output from the microwave circuit housed in the closed space is taken out through the coaxial connector.

Here, the cutting housing is widely used as a housing for a microwave circuit, but it is expensive because one product is cut one by one, but it has a large shield thickness and a high microwave shielding effect.

Next, as for the sheet metal casing, for example, an iron plate is processed into a sheet metal to form a casing having a bottom as shown in FIG. 4 (a), and the coaxial connector 33 is attached to the side surface. Further, as shown in FIG. 4A, a large number of spring-like tongue pieces 311 are attached around the lid 31.

Then, as shown in FIG. 4 (b), a circuit board mounting base 35 is provided in the housing, and the parts are mounted on the base.
The microwave circuit board 34 on which the 36 is mounted is fixed with screws, the coaxial connector and the terminals on the circuit board are connected, and then the lid 31
Is attached to the housing. At this time, the spring-like tongue attached to the lid comes into close contact with the housing.

Since the sheet metal housing has a poor shielding effect against microwaves, it is rarely used for microwave circuits and is used in a frequency band lower than the microwave band. The sheet metal housing is inexpensive because it is made only by sheet metal processing.

[0009]

DISCLOSURE OF THE INVENTION As described above,
The cutting housing has a high microwave shielding effect but is expensive, and the sheet metal housing is inexpensive, but there is a problem that the microwave shielding effect is low.

An object of the present invention is to improve the shield effect and reduce the cost.

[0011]

As shown in FIG. 1, 11 is a lid, 12 is a housing side surface, 14 is a circuit board, and 121 is a bent portion.

According to the present invention, a plurality of side surfaces of a housing made of a sheet metal structure are bent inward from one end by a predetermined length, and the bent portion and a space formed by the bent portion are covered with a flat lid.
The lid and the bent portion are fixed at a pitch of (1/2) or less of the used wavelength.

A space formed by the other ends of the plurality of housing side surfaces, a ground pattern formed on one surface of the circuit board having substantially the same shape, and a substantially entire circumference near the other ends of the plurality of housing side surfaces. , Made a structure to connect.

[0014]

[Operation] FIG. 2 is an explanatory view of microwave shielding conditions.
(a) is the case of a cutting housing, and (b) is the case of a sheet metal housing.

Generally, the attenuation of the microwave leaking from the gap of the housing is roughly obtained by using the formula for obtaining the attenuation of the cut-off waveguide. This formula is calculated by Maruzen Co., Ltd. on July 15, 1965. It is described on page 29 of "Microwave and Millimeter-Wave Circuits" by Bunichi Oguchi, which is as follows.

Α = 54.6 (L / 2W) [1- (2W / λ) ² ] ^1/2 ... (1) where α: attenuation (dB), L: length of waveguide (mm), W
: Waveguide width (mm) λ: Wavelength (mm) Therefore, from Equation (1), if the waveguide width W is small and the waveguide length L is large, the attenuation α is large, that is, the shield. It can be seen that the effect is high.

2A, even if there is a slight gap W ₁ between the lid 21 and the casing 22, the cutting casing shown in FIG. 2A is apt to leak due to the large thickness L _{1 of the} casing. Decays well. However, the sheet metal housing shown in FIG. 2 (b) has many gaps and the thickness L _{2 of the} housing is small, so that the microwave that leaks is hardly attenuated.

In any case, if λ <2W,
The equation (1) cannot be applied, and the microwave leaks without being attenuated. Therefore, in the present invention, for example, four side faces of the plurality of casings are formed by sheet metal processing, but are bent inward by a predetermined length L from one end of each side face of the casing. cover. And 1 / of the used wavelength
2 Fix the lid and the bent part at the pitch below.

Further, a circuit board having substantially the same shape as the space formed by the other ends of the plurality of housing side surfaces is inserted from the other ends of the plurality of housing side surfaces up to a predetermined distance. Then, the ground pattern formed on the back surface of the circuit board and substantially the entire circumference of the side surfaces of the plurality of housings near a predetermined distance are soldered, for example, to form a closed region.

As a result, the shield effect can be improved and the cost can be reduced.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a structural explanatory view of an embodiment of the present invention.
Is a perspective view of the housing for microwave circuit, (b) is the X-X 'of (a)
FIG.

Hereinafter, FIG. 1 will be described. First, for example,
Figure 1 after the iron plate is processed into sheet metal to make the four housing sides.
As shown in (a)-, the distance from the upper edge of the side of each housing
Bend about 90 degrees inward at the L part and connect the four bent parts by soldering.

Then, screw-mounting holes (123) whose pitch is 1/2 or less of the used frequency are provided in the four bent portions, and the coaxial connector 13 is attached to the side surface of the housing. Further, as shown in FIG. 1B, the circuit board 14 having the microwave circuit component 16 mounted on the front surface and the ground pattern 141 formed on the entire back surface is inserted from the other end of the side surface of the housing to a predetermined distance. Then, the ground pattern formed on the back surface of the circuit board and almost the entire circumference in the vicinity of the insertion point on the side surface of the housing are soldered 15 to eliminate the gap, and the connector and the circuit board are connected.

Further, the lid 11 (see FIG. 1 (a)-) for covering the four bent portions and the space formed by the four bent portions is provided with screw mounting holes 111, and these screw mounting holes 111 and 123 are provided. To fix the lid to the sheet metal housing.

That is, the width L of the bent portion is made the same as the thickness of the cutting housing, the lid and the bent portion are fixed at a pitch within 1/2 of the used wavelength, and the entire side surface of the inserted circuit board near the ground pattern is fixed. By soldering the circumference to eliminate the gap, an inexpensive sheet metal housing can achieve the same shielding effect as that of the cutting housing.

[0026]

As described above in detail, according to the present invention, the shield effect can be improved and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of an embodiment of the present invention, (a) is a perspective view of a microwave circuit housing, and (b) is a sectional view taken along line XX ′ of (a).

FIG. 2 is an explanatory diagram of microwave shield conditions, where (a) is a case of a cutting housing and (b) is a case of a sheet metal housing.

FIG. 3 is a structural explanatory view of a conventional example (in the case of a cutting housing),
(a) is a perspective view of the microwave circuit housing, (b) is the X- of (a)
It is an X'sectional view.

FIG. 4 is another structural explanatory view of the conventional example (in the case of a sheet metal housing)
Where (a) is a perspective view of the microwave circuit housing, and (b) is (a).
FIG. 6 is a sectional view taken along line XX ′ in FIG.

[Explanation of symbols]

 11 Lid 12 Side of housing 13 Coaxial plug 14 Circuit board 121 Bent portion 122 Space 141 Ground pattern

Claims (1)

[Claims] 1. A plurality of housing sides (12) made of sheet metal construction.
Bend inward for a specified length from one end of the
A flat lid between the (121) and the space (122) created by the bent portion.
The circuit board (14) is covered with (11), the lid and the bent portion are fixed at a pitch of (1/2) or less of the used wavelength, and the space formed by the other ends of the plurality of side surfaces of the housing has substantially the same shape. ) Ground pattern (14
A casing for a microwave circuit, characterized in that it has a structure in which 1) is connected to substantially the entire circumference near the other end of the plurality of casing side faces.