JPH03268396A - Shielding structure of microwave circuit enclosure - Google Patents

Abstract

PURPOSE:To obtain a good shielding characteristic at a microwave circuit enclosure which is small and lightweight and whose cost is low by a method wherein a metal thin-sheet structure whose one face is opened and in which a microwave circuit is fixed to and housed at the inner face is constituted of a main body and of a specific lid sheet of the enclosure. CONSTITUTION:A shielding structure having a part where a main body 2 of an enclosure comes into contact with a lid sheet 3 of a metal thin-sheet structure whose one face is opened and in which microwave circuits 9 are fixed to and housed at inner faces is formed in such a way that groove-shaped parts 4 of the lid sheet 3 come into contact with open edges so as to elastically sandwich them from both sides. Consequently, end corners on both sides of the edges 21 are set to a state that they come into contact with both internal faces of the groove-shaped parts 4. Even when the thickness of the edges 21 is thin, both come into contact surely without producing a gap. Thereby, a good shielding characteristic can be obtained at a small size, at a lightweight and at a low cost.

Description

[Detailed Description of the Invention] [Summary] Regarding a shielding structure for a microwave circuit case, an object of the present invention is to provide a shielding structure that provides good shielding characteristics in a small, lightweight, and low-cost microwave circuit case. The main body of the casing has a thin metal plate structure that is open on one side and firmly houses the microwave circuit on the back surface, and the edge of the main body that appears on the open surface is held at the same position along the edge so that the edge of the main body is elastically sandwiched. ,
It is composed of a cover plate formed by bending groove-shaped parts with intervals slightly narrower than the thickness of the edge.

[Industrial application field]

The present invention relates to a shielding structure for a microwave circuit case.

As the frequency of a component circuit increases, radio waves of that frequency are more likely to be radiated to the outside from the circuit components, and conversely, unnecessary signal radio waves from the outside world are more likely to mix into the circuit.

This is because the wavelength of the circuit frequency becomes shorter as the frequency becomes higher, and the antenna effect of the wiring portion becomes stronger.

For this reason, a shielding structure with good shielding properties is strongly required for a housing housing a microwave circuit.

[Conventional technology]

FIG. 3 shows a microwave circuit block diagram, FIG. 4 shows an example of a conventional microwave circuit case, and FIG. 5 shows another example of a conventional microwave circuit case.

To explain a microwave oscillator circuit as an example of a microwave circuit, as shown in the block diagram of FIG. Ru.

The microwave circuit is constructed by forming a pattern on a ceramic substrate for each circuit module, providing microstrip lines and components, and further mounting and mounting the components.

These circuits are housed in a microwave circuit housing to prevent circuit interference and are completed by interconnecting them.There are two types of housing structures, but both have one side open and the back side open. It is composed of a main body in which a circuit module is tightly and securely housed, and a cover plate that shields and covers the open surface of the main body.

A conventional example of a microwave circuit housing 15 is as shown in FIG. 4, and the main body 25 is made by cutting and polishing a block of conductive metal such as aluminum or brass into a predetermined shape.
The boards of each circuit are closely housed inside to form a microstrip line, and if necessary, a shielding partition is formed between the circuits, the open surface is finished flat, and a cover plate 35 is provided at the edge.
A screw hole 27 is drilled to fix it.

The cover plate 35 is a flat metal plate made of the same material as the main body 25 and has a thickness that does not easily bend and deform during handling, and covers the entire open surface and is screwed into contact with the edges without any gaps.

Another conventional microwave circuit housing 16 is as shown in FIG. 5, in which the main body 26 and the cover plate 36 are both molded from iron plates, and the surfaces are silver or fully plated.

The main body 26 has a shielding plate 28 erected between each circuit, and the cover plate 3S is provided with a contact piece 37 by bending the entire circumference.
This is a shielding structure in which a contact piece 37 elastically contacts the outer edge surface when placed over the open surface of the shield 6.

[Problem to be solved by the invention]

However, (1) the conventional casing I5 is made by cutting a block material, is expensive, leaves thick edges, and corners are difficult to form, and the shape of the bones becomes large, resulting in an increase in weight.

■ The housing 16 of another conventional example is of a sheet metal type, and can be lower in price, smaller in size, and lighter in weight than the housing 15, but the cover plate 36 surface is in contact with the open edge of the housing 16. Since the contact area is small and the plane is not polished, an uncertain gap is created and the shielding characteristics are deteriorated.
The gap acts as an antenna, allowing radio waves to radiate or penetrate.

There are other problems.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a shielding structure that provides good shielding characteristics with a small, lightweight, and low-cost microwave circuit housing.

[Means to solve the problem]

The above object is as shown in FIGS. 1 and 2. [1] A main body 2 of a thin metal plate structure with one side open and a microwave circuit 9 fixedly housed in the back surface, and a main body appearing on the open surface. MtH3 is formed by bending and forming groove-like portions 4 at intervals slightly narrower than one dimension of the edge 21 at the same position along the edge 21 so as to elastically sandwich the edge 21 of the 2. This is achieved by the shielding structure of the microwave circuit case of the present invention.

[2] Also, the lid plate 3 whose entire periphery is surrounded by the grooved portion 4
The partial surface 5 forms a plane narrowed to a predetermined depth compared to the other partial surfaces 51, and selectively imparts a predetermined filter characteristic to the microwave circuit of the main body 2 corresponding to the partial surface 5.
This can also be achieved by the shielding structure of the microwave circuit case of the second invention described in item 1].

[For production]

That is, since the casing l has a thin metal plate structure, it is low cost, small, and lightweight.

The shielding structure of the contact portion between the main body 2 and the lid plate 3 is such that the grooved portion 4 of the lid plate 3 contacts the open edge 21 by elastically pinching it from both sides, so that the end corners of both sides of the edge 21 are formed into grooves. It comes into contact with both inner surfaces of the shaped part 4, and even if the thickness of the edge 21 is thin, the contact is ensured without any gaps, so that good shielding properties can be obtained.

Furthermore, in the second invention, in addition to the shielding property, a predetermined distance is obtained between the partial surface 5 and the opposing rear surface of the main body 2, and this distance allows the microwave circuit 9 of the microstrip line filter housed in that portion to be Cut the low frequency range for
Since the cut-off frequency can be changed, it can be set to a predetermined value.

In this way, it is possible to provide a shielding structure that provides good shielding characteristics with a small, lightweight, and low-cost microwave circuit case, and furthermore, it is possible to provide a shielding structure that provides good shielding characteristics for the housed microwave circuit. can also be easily added.

〔Example〕

The present invention will be specifically described below with reference to embodiments shown in the drawings. The same reference numerals indicate the same objects throughout the figures. Figure 1 (
Fig. 2(a) is a configuration diagram of an embodiment of the present invention, Fig. 2(a) is an enlarged cross-sectional view of the shielding structure, and Fig. 2(a) is a configuration diagram of an embodiment of the second invention. (b) shows an enlarged sectional view of the contact portion.

The present embodiments are all implemented using the same microwave oscillation circuit (see FIG. 3) as the conventional example described above.

That is, this microwave oscillation circuit includes a voltage controlled oscillator 91
, an amplifier 92, and a multiplier 93, each of which outputs a predetermined microwave frequency.

Each microwave circuit 9 is formed by forming a pattern on a ceramic substrate, providing microstrip lines and components, and further mounting and mounting the components to configure the microwave circuit 9.

These circuits are housed in a microwave circuit housing so as not to cause circuit interference, are interconnected, and are sufficiently shielded from the outside world.

In the present invention, as shown in FIG. 1(a), a gold-plated casing 1 is made of thin iron plate and has an outer diameter of 50 x 7 ox and a height of 15 mm, and is composed of a main body 2 and a cover plate 3.

The main body 2 is a rectangular parallelepiped made of a 0.8 m thick plate with one side open, and the interior is partitioned into three rooms with a shielding plate, each microwave circuit 9 is fixed to the back, and microstrip lines are interconnected. , connection to a power supply terminal provided on one side, and output connection to a connector provided on another side.

The cover plate 3 that covers the entire open surface of the main body 2 is 0.3+
A plate with a thickness of wa is used, and along the edge 21 appearing on the open surface of the main body 2, a groove-shaped portion 4 is provided at the same position by press molding.

As shown in FIG. 1(b), the groove portion 4 has a groove width of 0.6 mm, which is slightly smaller than the thickness dimension of the edge 21 of 0.8 mm, and a depth of approximately 2 mm. By applying it, the groove-shaped portion 4 is fitted into the edge 21, and the inner surfaces of the groove are elastically contacted and clamped to ensure conduction and to shield the entire circumference of the edge 21 without any gaps.

In order to prevent it from coming off during handling, it is fixed to the main body 2 with screws at multiple locations (not shown).

In the case 11 of the second invention, as shown in FIG. 2(a),
The partial surface 5 of the cover plate 31 surrounded by the groove-shaped portion 4, which corresponds to the multiplier 93 of the microwave circuit 9, is a plane that is narrowed to a predetermined depth compared to the other partial surface 51. C of
A filter characteristic that cuts the low frequency range at the ut-off frequency is selectively provided.

In the figure, when the H dimension changes, the cut-off frequency changes, so the H dimension is set according to the characteristics.

In this state, as shown in Figure (b), the grooves 4 of the cover plate 31 are fitted and in contact with both end corners of the edge 21 of the main body 2, and the partial surface 5 is separated from the contact position. .

Therefore, it is necessary to experimentally determine the H dimension.

In addition, in order to obtain accurate filter characteristics, as shown in the figure, a contact member 6 of an elastic conductor, such as a molded member of a phosphor bronze thin plate, is protruded and fixed to the peripheral edge 52 of the partial surface 5, and the shielding wall 22 of the main body 2 is fixed. If conduction is made at the position of partial surface 5, 6 at the design stage.
Dimensions can be set.

The above embodiment shows one example, and the shapes and dimensions of each part of the microwave circuit 9 and the casings 1 and 11 are not limited to those described above.

〔Effect of the invention〕

As described above, the microwave casing made of a metal plate of the present invention provides a shielding structure that is small, lightweight, low cost, and has good shielding characteristics, and can be selected for the microwave circuit to be accommodated. Therefore, it is possible to easily add the characteristics of a low frequency rejection filter, and the practical effects thereof are great.

It is.

In the figure, Lll, 15.16 is the housing, 3.31, 35.36 are lid plates, 5.51 is a partial surface, 9 is a microwave circuit, 22 is a shielding wall; 28 is a shielding plate; 52 is the periphery; 92 is an amplifier, 2.25.26 is the main body, 4 is a grooved part; 6 is a contact member; 21 is the edge; 27 hole, 37 is a contact piece; 91 is a voltage controlled oscillator; 93 is a multiplier.

[Brief explanation of drawings]

Fig. 1 is an embodiment of the present invention, Fig. 2 is an embodiment of the second invention, Fig. 3 is a microwave circuit block diagram, Fig. 4 is an example of a conventional microwave circuit case, and Fig. Figure 5 shows another example of the conventional microwave circuit housing 4 - the power of the second invention IJ Figure 2 Microwave recirculation housing of the conventional microwave circuit case 4 Figure 5

Claims (1)

[Scope of Claims] [1] A main body (2) of a casing (1) having a metal thin plate structure with one side open and a microwave circuit (9) fixedly housed on the rear surface;
at the same position along the edge (21) so as to elastically clamp the edge (21) of the main body (2) appearing on the open surface;
Grooves (4) with intervals slightly narrower than the thickness of the edge (21).
) and a cover plate (3) provided by bending and forming. [2] The cover plate (
The partial surface (5) of 3) is formed into a plane that is narrowed to a predetermined depth compared to the other partial surface (51), and the microwave circuit (9) of the main body (2) corresponding to the partial surface (5) is formed to have a predetermined shape. 2. The shielding structure for a microwave circuit case according to claim 1, wherein the filter characteristic of the microwave circuit case is selectively imparted.