JP2002185176A - Electromagnetic wave suppression body and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress effectively an electromagnetic wave invading from the outer space or leaking out the outer space through a transmission cable that is passed through an electromagnetic shielding body. SOLUTION: Part of a transmission cable 14 passed through an electromagnetic shielding body 12 is covered with a loss dielectric body 16 having an end face put in contact with the electromagnetic shielding body 12. At the same time, the part of the transmission cable 14 is covered with a magnetic body 18 through the part of the loss dielectric body 16. The magnetic body 18 is covered with an outer conductive body 20 grounded to the electromagnetic shielding body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic wave suppressor for suppressing electromagnetic waves that enter from an external space or leak to an external space via a transmission cable disposed through an electromagnetic shield constituting an electromagnetic shield space. The present invention relates to a body and an electromagnetic wave suppression method.

[0002]

2. Description of the Related Art When an electromagnetic wave intrudes from an external space through a transmission cable for connecting electronic devices electromagnetically shielded by a housing (electromagnetic shield) of a computer or a peripheral device thereof, the electronic device may malfunction. On the other hand, if electromagnetic waves leak to the external space via the transmission cable, there is a possibility that peripheral electronic devices will be adversely affected. For this reason, it has been practiced to fit a cylindrical ferrite called a ferrite clamp to a part of the transmission cable. As a result, a certain effect can be expected in suppressing electromagnetic waves that intrude from the external space via the transmission cable or leak to the external space.

[0003]

However, if only a ferrite clamp is used, the suppression effect against electromagnetic waves fluctuates depending on the impedance of the transmission circuit, the operating frequency, and the like. There is a problem that there is a certain limit to effectively suppress the leaked electromagnetic waves.

FIG. 10 shows a ferrite clamp (inner diameter 5 mm, outer diameter 15 mm, length 3) attached to a transmission cable.
10 is a graph showing the suppression characteristics (attenuation characteristics) of the electromagnetic wave when 0 mm) is attached. As shown in FIG. 11, this suppression characteristic is obtained by connecting a load 101 to a high-frequency power supply 103 via a transmission cable 102 and attaching a ferrite clamp 104 to the transmission cable 102 to leak from the transmission cable 102 to the external space. FIG. 6 shows the case where the impedance of the electromagnetic wave to be applied is set to 10Ω and 1KΩ for the impedances Z _G and Z _L of the load 101 and the high frequency power supply 103, respectively. Note that the horizontal axis represents frequency (log scale) and the vertical axis represents attenuation.

In FIG. 10, a case where the impedances Z _G and Z _L are 10Ω is indicated by a symbol C, and a case where the impedances Z _G and Z _L are 1 KΩ is indicated by a symbol D. As is apparent from the suppression characteristics shown in FIG. 10, when the impedances Z _G and Z _L indicated by the symbol C are 10Ω, 0.1
In a low frequency range up to around GHz, the attenuation is about 25 dB, but in a high frequency range around 0.1 GHz, the attenuation is sharply reduced. Further, when the impedances Z _G and Z _L indicated by the symbol D are 1 KΩ, almost no attenuation can be expected in the entire measurement frequency range.

As described above, while the suppression effect on the electromagnetic wave varies depending on the impedance of the transmission circuit and the operating frequency, the impedance of the load 101 and the high-frequency power supply 103 is actually the radiation impedance of the transmission cable 102 existing in the space. Is unstable depending on the spatial structure including the transmission cable 102, so that it is difficult to effectively suppress intrusion and leakage of electromagnetic waves from the transmission cable 102. .

[0007] The problem of the invasion and leakage of such electromagnetic waves is not limited to transmission cables for connecting electronic devices such as computers and the like. A transmission cable that constitutes a communication line such as a telephone line that performs data transmission in a high frequency range, and an electromagnetic shield that connects between the arm and the robot body that is covered with an electromagnetic shield such as a housing This also occurs for various transmission cables such as transmission cables disposed through the cable.

The present invention has been made in view of such circumstances, and has an effect of preventing electromagnetic waves that intrude from an external space or leak to the external space via a transmission cable disposed through an electromagnetic shield. It is an object of the present invention to provide an electromagnetic wave suppressing body and an electromagnetic wave suppressing method capable of suppressing electromagnetic waves.

[0009]

In order to achieve the above-mentioned object, the invention according to the first aspect is directed to a method of intruding from an external space through a transmission cable disposed through an electromagnetic shield constituting an electromagnetic shield space. Or an electromagnetic wave suppressor that suppresses electromagnetic waves leaking to the external space, a magnetic body externally fitted to a part of the transmission cable, and a jacket conductor that covers the magnetic body and is grounded to the electromagnetic shield. A loss dielectric which is fitted to at least a region of the transmission cable adjacent to the magnetic body and grounded to the electromagnetic shield at a position close to the electromagnetic shield.

According to this structure, the electromagnetic wave is effectively absorbed by the action of the magnetic material and the lossy dielectric material, and the electromagnetic wave that enters from the external space or leaks to the external space via the transmission cable. Effectively suppressed.

According to a second aspect of the present invention, in the first aspect, the lossy dielectric is formed with an extended portion disposed in a region where the magnetic material of the transmission cable is externally fitted. Wherein the magnetic body is fitted externally to the transmission cable via the extending portion.

According to this structure, the electromagnetic wave is effectively absorbed by the action of the loss dielectric and the magnetic material covering the loss dielectric, and the electromagnetic wave or the external space that enters from the external space via the transmission cable is transmitted. Electromagnetic waves leaking to the hood are effectively suppressed.

According to a third aspect of the present invention, in the first aspect, the lossy dielectric is formed at one end with an extension having a shape covering the magnetic body. , Thereby constituting the jacket conductor.

According to this structure, by covering the magnetic body with the extension formed at one end of the loss dielectric, the action of the loss dielectric and the magnetic body is combined to effectively absorb the electromagnetic wave,
Electromagnetic waves that enter from the external space or leak to the external space via the transmission cable are effectively suppressed.

[0015] The invention of claim 4 is the invention of claim 2 or 3.
Wherein the lossy dielectric is made of a flexible material.

According to this structure, the electromagnetic wave entering from the external space or leaking to the external space via the transmission cable is effectively suppressed, while the edge of the transmission cable against the magnetic body is reinforced, and the transmission cable is reinforced. Damage to the edges of the magnetic material of the cable is effectively prevented.

Further, the invention of claim 5 provides the invention according to claims 1 to 3
Any one of the above, wherein the lossy dielectric has a sponge structure.

According to this configuration, the lossy dielectric can be disposed in a state of being elastically adhered to the transmission cable. As a result, the lossy dielectric is disposed in the transmission cable in a stable state, and the stable suppression is achieved. Characteristics are obtained.

According to a sixth aspect of the present invention, there is provided an electromagnetic wave for suppressing an electromagnetic wave entering from an external space or leaking to an external space via a transmission cable disposed through an electromagnetic shield constituting an electromagnetic shielding space. In a suppression method, a magnetic body is externally fitted to a part of the transmission cable, and a lossy dielectric is externally fitted to at least a region adjacent to the magnetic body of the transmission cable, and the magnetic body is covered with a jacket conductor. In addition, the outer conductor is grounded to the electromagnetic shield, and the lossy dielectric is grounded to the electromagnetic shield at a position close to the electromagnetic shield.

According to this method, the electromagnetic wave is effectively absorbed by the combined action of the lossy dielectric and the magnetic material, and the electromagnetic wave that enters from the external space or leaks to the external space via the transmission cable. Effectively suppressed.

[0021]

1 is a side sectional view of an electromagnetic wave suppressor according to a first embodiment of the present invention, and FIG.
3 is an external perspective view of the electromagnetic wave suppressor. In these figures, the electromagnetic wave suppressor 10
Loss dielectric 16 disposed so as to cover the area near electromagnetic shield 12 of transmission cable 14 penetrating electromagnetic shield 12
And the magnetic body 1 disposed so as to cover the area near the electromagnetic shield 12 of the transmission cable 14 via the lossy dielectric 16.
8 and a jacket conductor 20 arranged to cover the magnetic body 18.

The electromagnetic shield 12 has a ground potential made of a metal plate or the like, and forms an electromagnetic shield space such as a housing of electronic equipment or a robot or a shield room. In addition, the transmission cable 14 includes a pair of core wires 141 having a diameter of 1 mm and a cable jacket 14 having a diameter of 1.6 mm.
2.

The loss dielectric 16 includes urethane foam as a base material (basic dielectric material) mixed with a predetermined amount of carbon graphite as a conductivity-imparting material (for example, about 40 grams of carbon graphite per liter of urethane foam). It is formed into a sponge shape, and has a cylindrical shape (for example, having an outer diameter of 5 mm and a length of 15
0 mm). As described above, the loss dielectric 16 uses urethane foam as a base material and contains a large amount of air therein, so that the real part of the complex permittivity can be made close to 1, thereby increasing the dielectric loss. be able to.

In this embodiment, the loss dielectric 16 is
Before the transmission cable 14 penetrates the electromagnetic shield 12 and is disposed, the transmission cable 14 is inserted into the through-hole 161 so as to be fitted on the transmission cable 14. In the present embodiment, the loss dielectric 16 is grounded by bringing one end face into contact with the electromagnetic shield 12. Since the lossy dielectric 16 has a sponge structure, the inner diameter of the transmission cable 14 is set to be slightly smaller than the outer diameter of the transmission cable 14.
So that it is elastically close to the body. As a result, the lossy dielectric 16 can be externally fitted to the transmission cable 14 in a stable state, so that stable suppression characteristics against electromagnetic waves can be obtained.

The magnetic material 18 is a ferrite core (for example, having an inner diameter of 5 mm) which is a cylindrical soft magnetic material having a through hole 181 at the center.
mm, an outer diameter of 15 mm, and a length of 28 mm), and a part (substantially half in the drawing) of the loss dielectric 16 is inserted through the through hole 181 in a state of being in close contact with the loss dielectric 16. It is arranged so as to cover. In this embodiment, the magnetic body 18 is formed by inserting the through hole 181 into the transmission cable 14 and the loss dielectric 16 before the transmission cable 14 is penetrated through the electromagnetic shield 12 and disposed. The transmission cable 14 is externally fitted via a part thereof. In addition, since the loss dielectric 16 is set to be longer than the magnetic body 18, the loss dielectric 16 is configured to be fitted to a region of the transmission cable 14 adjacent to the magnetic body 18. Have been.

The jacket conductor 20 is formed of a cylindrical metal case, and has a metal flange 22 integrally attached to the electromagnetic shield 12 side.
The jacket conductor 20 made of a metal case is disposed in close contact with the outer peripheral surface of the magnetic body 18, and the protrusion 201 formed on one end side is formed into an engagement hole 221 formed in the flange 22. And is bent at the back side to be integrally attached to the flange portion 22. A plurality of mounting holes 222 for inserting nuts are formed in the flange portion 22 at appropriate positions in the circumferential direction, and the nut 22 is screwed through the mounting holes 222 to be mounted on the electromagnetic shield 12. As a result, the jacket conductor 20 is grounded by being connected to the electromagnetic shield 12.

The magnetic material 18 in the lossy dielectric 16
If the jacket conductor 20 is provided in a portion where no magnetic material 18 exists, the loss resistance disappears due to the proximity effect of the conductor. Therefore, the jacket conductor 20 should not be provided in a portion of the loss dielectric 16 where the magnetic body 18 does not exist. I have to. However, in the present embodiment, a part of the end face portion 202 covering the end face of the magnetic body 18 of the jacket conductor 20 comes in contact with a part of the outer peripheral surface of the loss dielectric 16, and When grounded, the loss dielectric 16 is also grounded at the contact portion.

FIG. 4 shows the electromagnetic wave suppression characteristics of the electromagnetic wave suppressor 10 constructed as described above in the frequency range of 0.01 to 1.0 GHz. Note that FIG.
The horizontal axis represents the frequency (logarithmic scale), and the vertical axis represents the attenuation (linear scale). The suppression characteristics of the electromagnetic wave shown in FIG. 4 are obtained as follows.

That is, as shown in FIG. 5, the electromagnetic wave suppressor 10 is fitted over the transmission cable 14 and the flange 22 of the jacket conductor 20 is attached to the electromagnetic shield 12. In this state, the high-frequency power supply 24 is connected to one end of the core 141 of the transmission cable 14, and the load 26 is connected to the other end of the core 141, so that electromagnetic waves of a predetermined level are transmitted in a frequency range of 0.01 to 1.0 GHz. It is radiated to the external space via the cable 14.

When the impedances Z _G and Z _L of the high-frequency power supply 24 and the load 26 are set to 10Ω and 1 KΩ, respectively, the antenna is induced by the small antenna 28 installed at a predetermined distance from the transmission cable 14. Is measured by an RF level meter 30 and the amount of attenuation is determined based on a case where the electromagnetic wave suppressor 10 is not attached to the transmission cable 14.

As is clear from the characteristic diagram of FIG. 4, both when the impedances Z _G and Z _L indicated by the symbol A are 10Ω and when the impedances Z _G and Z _L indicated by the symbol B are 1 KΩ,
Both exhibit a large attenuation, and exhibit excellent attenuation characteristics, in particular, the attenuation increases as the frequency increases.

The reason why the electromagnetic wave suppressor 10 according to the above-described embodiment has excellent suppression characteristics against electromagnetic waves is as follows. That is, the transmission cable 1
4 can reduce the equivalent impedance of the transmission cable 14 by fitting the lossy dielectric 16 to the outside, and can reduce the transmission impedance by grounding the magnetic body 18 to form a coaxial transmission system. ,
The effect of suppressing electromagnetic waves by the magnetic body 18 in a low frequency range can be enhanced. Further, in a high frequency region (for example, 0.3 GHz or more), the effect of suppressing the electromagnetic wave by the magnetic body 18 cannot be expected, but the transmission loss of the transmission cable 14 may increase as the frequency increases due to the presence of the lossy dielectric 16. As a result, the effect of suppressing electromagnetic waves in a high frequency region can be enhanced.

FIG. 6 is a side sectional view of an electromagnetic wave suppressor according to a second embodiment of the present invention. The electromagnetic wave suppressor 10a shown in this drawing is different from the electromagnetic wave suppressor 10 of the first embodiment in that a lossy dielectric and a magnetic material are disposed so as to cover different areas of a transmission cable.

That is, the electromagnetic wave suppressor 10a is disposed so that the magnetic body 18a covers the area near the electromagnetic shield 12a of the transmission cable 14a, and the loss dielectric 16a
a is provided so as to cover a region adjacent to the region covered with the magnetic body 18a in the transmission cable 14a. The loss dielectric 16a has a flange 161a integrally formed on the side adjacent to the magnetic body 18a, and the flange 161a and the magnetic body 18a are connected to the outer conductor 20a.
a, and the jacket conductor 20a is
And is connected to the electromagnetic shield 12a via the ground.

The electromagnetic shield 12a, the transmission cable 1
4a, lossy dielectric 16a, magnetic body 18a and sheath conductor 2
0a is the electromagnetic shield 12, transmission cable 14, loss dielectric 16, magnetic body 18 in the first embodiment except that the shapes of the loss dielectric 16a and the magnetic body 18a are partially different.
And the outer conductor 20 have the same configuration.

In the electromagnetic wave suppressor 10a according to the second embodiment thus configured, the loss dielectric 16a is connected to the electromagnetic shield 12a by covering the flange portion 161a of the loss dielectric 16a with the jacket conductor 20a. Will be
The same excellent suppression characteristics as the electromagnetic wave suppressor 10 of the first embodiment shown in FIG. 4 are exhibited. That is, as is apparent from the first and second embodiments, the lossy dielectric 1
6, 16a are externally fitted to at least areas of the transmission cables 14, 14a adjacent to the magnetic bodies 18, 18a, and these lossy dielectrics 16, 16a are attached to the electromagnetic shields 12, 12a at positions near the electromagnetic shields 12, 12a. By being grounded, excellent suppression characteristics are exhibited.

FIG. 7 is a side sectional view of an electromagnetic wave suppressor according to a third embodiment of the present invention. The electromagnetic wave suppressor 10b shown in this figure is different in that the lossy dielectric and the magnetic body are disposed so as to cover different areas of the transmission cable, and that the magnetic body is covered by an extension of the lossy dielectric. This is different from the electromagnetic wave suppressor 10 of the first embodiment.

That is, the electromagnetic wave suppressor 10b is disposed so that the magnetic body 18b covers the area near the electromagnetic shield 12b of the transmission cable 14b, and the loss dielectric 16
b is disposed so as to cover an area adjacent to the area covered by the magnetic body 18b in the transmission cable 14b. Further, one end of the loss dielectric 16b is connected to a magnetic body 18b.
Is formed integrally, and the end 162b of the extension 161b is connected to the electromagnetic shield 12b to be grounded.

The electromagnetic shield 12b, the transmission cable 1
4b, the lossy dielectric 16b and the magnetic body 18b are the same as the electromagnetic shield 12, the transmission cable 14, the lossy dielectric 16 and the electromagnetic shield 12 in the first embodiment except that the shapes of the lossy dielectric 16b and the magnetic body 18b are partially different. The magnetic members 18 have the same configuration. Further, the extending portion 161b of the lossy dielectric 16b substantially constitutes the jacket conductor 20 in the first embodiment.

In the electromagnetic wave suppressor 10b according to the third embodiment having the above-described configuration, the magnetic body 18b is made of the lossy dielectric 1b.
The magnetic body 18 is covered by the extension portion 161b of the magnetic body 18b.
b is grounded to the electromagnetic shield 12b, and the lossy dielectric 16b is also grounded to the electromagnetic shield 12b at a position near the electromagnetic shield 12b, so that the electromagnetic wave suppressor 10 of the first embodiment shown in FIG. And exhibits excellent suppression characteristics substantially similar to the above.

The electromagnetic wave suppressor according to the present invention comprises, as in the above-described embodiment, a magnetic body fitted externally to a part of the transmission cable, and a jacket conductor covering the magnetic body and grounded to the electromagnetic shield. A loss dielectric that is externally fitted to at least a region adjacent to the magnetic body of the transmission cable and grounded to the electromagnetic shield at a position near the electromagnetic shield. Further, the electromagnetic wave suppression method according to the present invention, as in the above embodiment, externally fitting a magnetic material to a part of the transmission cable and externally fitting a loss dielectric to at least a region adjacent to the magnetic material of the transmission cable, The magnetic body is covered with a jacket conductor, the jacket conductor is grounded to an electromagnetic shield, and the lossy dielectric is grounded to the electromagnetic shield at a position near the electromagnetic shield. For this reason, the action of the magnetic material and the lossy dielectric material is combined to effectively suppress electromagnetic waves that enter from the external space or leak to the external space via the transmission cable.

It should be noted that the present invention is not limited to the above-described embodiments, but may adopt various modifications as described below.

(1) In each of the above embodiments, the lossy dielectric 1
6, 16a and 16b use urethane foam as a base material, but are not limited thereto. For example, other foamed plastics such as foamed polyester may be used. Of course, it is also possible to use a dielectric material such as a non-foamable plastic. In addition, although carbon graphite is used as the conductivity-imparting material, it is not limited thereto. For example, carbon powder,
Another powder material such as a conductive metal may be used.

It is also possible to use a non-woven fabric having a predetermined sheet resistance by incorporating carbonized fibers or the like without using foamed plastic. Moreover,
Ferrite rubber (rubber mixed with ferrite powder),
Carbon rubber (rubber mixed with carbon powder) or the like can also be used.

Since foamed plastic, non-woven fabric, ferrite rubber, carbon rubber and the like have flexibility (flexibility), the end portions of the magnetic bodies 18, 18a, 18b in the transmission cables 14, 14a, 14b. Can be reinforced, and the transmission cables 14, 14a, 14b
It can be effectively prevented from being easily damaged by being bent at the end portions of 8, 18a and 18b. Of course, it is needless to say that a material having no flexibility (flexibility) can be used.

(2) In each of the above embodiments, the lossy dielectric 1
6, 16a and 16b transmit the transmission cables 14, 14a and 14b before the transmission cable 14 penetrates the electromagnetic shield 12.
b, but is not limited to this. For example, a divided structure such as splitting into two along the axial direction is provided, and the divided pieces (divided portions) are abutted to each other from the outer periphery of the transmission cables 14, 14a, 14b and adhered with an adhesive or an adhesive tape. May be integrated by winding and fixing. In the case of such a configuration, even after the transmission cables 14, 14a, 14b are installed, the transmission cables 14, 14a, 14b can be disposed.

(3) In each of the above embodiments, the magnetic material 18,
18a and 18b are made of ferrite,
Even those made of other magnetic materials can be used.

The magnetic members 18, 18a, 18b are used to connect the transmission cables 14, 14a, 14b to the electromagnetic shields 12, 1, respectively.
Before passing through the transmission cables 14 and 14
a, 14b, but is not limited to this. For example, a divided structure such as splitting into two along the axial direction is provided, and the divided pieces (divided portions) are abutted to each other from the outer periphery of the transmission cable 14 and adhered by an adhesive or fixed by winding an adhesive tape. Alternatively, they may be integrated.

When the outer conductor 20 is formed of a metal case, the outer conductor 20 is divided into two parts, for example, and an engagement portion is provided at each abutting portion. The outer conductors 20 are integrated by engaging with each other at these engaging portions, so that the magnetic members 18, 18a,
18b may be integrated.

(4) In the first and second embodiments, the jacket conductor 20 is formed of a metal case.
It is not limited to this. For example, the magnetic members 18 and 18a
May be made of a metal film formed on the outer peripheral surface by a conductor applying means such as plating or coating. In this case, the metal film is coated with the flange portions 22 and 22a with solder or conductive adhesive.
It should just be connected to. In addition, the flange portion 22,
The metal film may be directly connected to the electromagnetic shields 12 and 12a without using the metal film 22a. The outer conductor 2
When 0 is formed of a metal film, in the second embodiment, the metal film may be extended to a position adjacent to the magnetic body 18a of the lossy dielectric 16a. Thereby, the loss dielectric 16a can be grounded to the electromagnetic shield 12a at a position close to the electromagnetic shield 12a.

(5) In each of the above embodiments, the pair of core wires 1
Although the example of application to the transmission cables 14, 14a, and 14b having 41 has been described, it is needless to say that the present invention is applicable to various transmission cables such as a single-core transmission cable and a cable having a plurality of pairs of core wires. Nor. In the case of a transmission cable having a plurality of core wires such as a pair of core wires or a plurality of pairs of core wires, suppression of electromagnetic waves effectively works only in the common mode, and hardly affects the normal mode used for information transmission. Since there is no data, data can be transmitted efficiently.

(6) In the first embodiment, the loss dielectric 16 is grounded by bringing one end surface thereof into contact with the electromagnetic shield 12, while the end surface 202 of the outer conductor 20 covering the magnetic body 18 is grounded. Although a part is brought into contact with a part of the outer peripheral surface of the loss dielectric 16 so as to be grounded to the electromagnetic shield 12, it is not limited to this.

For example, when one end face of the lossy dielectric 16 is brought into contact with the electromagnetic shield 12, the end face 202 of the jacket conductor 20 does not necessarily need to be in contact with the outer peripheral face of the lossy dielectric 16. When the end surface portion 202 of the jacket conductor 20 is brought into contact with the outer peripheral surface of the loss dielectric 16, one end surface of the loss dielectric 16 does not necessarily need to be in contact with the electromagnetic shield 12. The point is that the lossy dielectric 16 is
It is sufficient that the electromagnetic shield 12 is grounded at a position close to.

The electromagnetic shields 12, 12 of the lossy dielectrics 16, 16a, 16b in the first to third embodiments.
In the first embodiment, the position close to a, 12b means a position on one end face or a side adjacent to the magnetic body 18, and the second, third
In the embodiment, the position on the side adjacent to the magnetic bodies 18a and 18b is set.

(7) In the second and third embodiments, the lossy dielectrics 16a and 16b are disposed adjacent to the magnetic bodies 18a and 18b and in contact with the magnetic bodies 18a and 18b. , But is not limited to this. For example,
It is also possible to dispose the lossy dielectrics 16a and 16b adjacent to the magnetic bodies 18a and 18b and at a position slightly separated from the magnetic bodies 18a and 18b. In this case, the electromagnetic shields 12a, 12b of the lossy dielectrics 16a, 16b are formed by appropriate means.
The electromagnetic shields 12a and 12b may be grounded at a position close to.

(8) In each of the above embodiments, the transmission cables 14, 14a, 14b are connected to the electromagnetic shields 12, 12a, 12b.
Although the description has been given of the case where the component is directly inserted into the through hole b, the configuration is not limited to this. For example, the electromagnetic wave suppressor may be configured in a connector structure, and the transmission cable may be connected to the electromagnetic wave suppressor in the connector structure to penetrate the electromagnetic shield.

FIG. 8 is a diagram showing an example of the configuration.
That is, the electromagnetic wave suppressor 32 having the connector structure is
A magnetic body 34 made of a cylindrical ferrite core or the like having a through hole 341 at the center, a jacket conductor 36 made of a metal cylinder or the like covering the outer periphery of the magnetic body 34, and a through hole 3 of the magnetic body 34
A metal pin body 38 provided in 41 and a part of the transmission cable 40 that covers a region adjacent to the magnetic body 34 and covers a part of the magnetic body 34 via the outer conductor 36. And a loss dielectric 42 made of carbon rubber or the like. The transmission cable 40 is of a two-core type. One core wire 401 is connected to the pin body 38, and the other core wire 402 is connected to the jacket conductor 36. That is, since the core wire 401 of the transmission cable 40 is connected to the pin body 38, the pin body 38 substantially becomes a part of the transmission cable 40, so that the magnetic body 34 has a structure covering the transmission cable 40. I have.

The electromagnetic wave suppressor 32 constructed as described above
Is a metal fitting pin 461 of the other connector 46 attached to the electromagnetic shielding body 44 similar to the electromagnetic shielding body 12 in the first embodiment (the fitting pin 461 has an opposite side to the electromagnetic shielding body 44). The core of the magnetic body 34 is inserted into the metal receptacle 462 in a state where the pin body 38 is inserted into the core wire of another transmission cable provided.). 40 is passed through the electromagnetic shield 44. The distal end side of the magnetic body 34 is fitted into the metal receptacle 462, so that the outer conductor 36 is grounded to the electromagnetic shield 44 via the connector 46 on the opposite side. When the loss dielectric 42 is in contact with the outer conductor 36, a position near the electromagnetic shield 44 is grounded to the electromagnetic shield 44 via the outer conductor 36. The electromagnetic wave suppressor 32 having such a connector structure also exhibits substantially the same excellent suppression characteristics as the electromagnetic wave suppressor 10 of the first embodiment shown in FIG.

FIG. 9 is a diagram showing another configuration example of the electromagnetic wave suppressor having the connector structure shown in FIG. That is, the electromagnetic wave suppressor 48 having the connector structure includes a holding member 50 made of an insulating material for holding five metal pin bodies 501 whose front end portions project forward, and a through hole 5 at the center.
A magnetic body 52 made of a cylindrical ferrite core or the like having a rear end of the pin body 501 inserted into the through hole 521;
A loss dielectric 56 made of carbon rubber or the like, which covers a part of the transmission cable 54 adjacent to the magnetic body 52, and the holding member 50, the magnetic body 52, and the magnetic body 52 of the loss dielectric 56. And a cylindrical support 60 made of an insulating material and disposed around the outer periphery of the lossy dielectric 56 and connected and fixed to the outer conductor 58. It is composed of

The transmission cable 54 is of a five-core type, and each core wire 541 is connected to a pin body 501. That is, each core 5 of the transmission cable 54
Since 41 is connected to each pin body 501, each pin body 501 becomes substantially a part of the transmission cable 54, and as a result,
The magnetic body 52 has a structure that covers the transmission cable 54.

The electromagnetic wave suppressor 48 thus configured
Are five metal fitting pins 641 of the other connector 64 attached to the electromagnetic shield 62 similar to the electromagnetic shield 12 in the first embodiment (each fitting pin 641 has the electromagnetic shield 62 Are connected to the respective core wires of another transmission cable disposed on the opposite side of the pin body 501).
The transmission cable 54 penetrates through the electromagnetic shield 62 by fitting the distal end side of the holding member 50 into the metal receiving port 462 in a press-contact state in a state where the cable is inserted. When the distal end side of the holding member 50 is fitted into the metal receiving port 462, the outer conductor 58 is brought into contact with the other connector 64, so that the outer conductor 58 is connected to the electromagnetic shield 62 through the connector 64. Grounded. In addition, since the portion of the loss dielectric 56 adjacent to the magnetic body 52 is covered with the sheath conductor 58, a position near the electromagnetic shield 62 is grounded to the electromagnetic shield 62 via the sheath conductor 58. . The electromagnetic wave suppressor 48 having such a connector structure also has the first structure shown in FIG.
The same excellent suppression characteristics as the electromagnetic wave suppressor 10 of the embodiment are exhibited.

[0062]

As described above, according to the electromagnetic wave suppressors of the first to fifth aspects, the magnetic body fitted to a part of the transmission cable, and the magnetic body is covered and grounded to the electromagnetic shield. And a lossy dielectric that is externally fitted to at least a region adjacent to the magnetic body of the transmission cable and is grounded to the electromagnetic shield at a position close to the electromagnetic shield. The electromagnetic wave is effectively absorbed by the action of the lossy dielectric material, and the electromagnetic wave entering from the external space or leaking to the external space via the transmission cable can be effectively suppressed.

According to the electromagnetic wave suppressing method of the sixth aspect, the magnetic material is externally fitted to a part of the transmission cable, and the lossy dielectric is externally fitted to at least a region of the transmission cable adjacent to the magnetic material. The body is covered with a jacket conductor, the jacket conductor is grounded to an electromagnetic shield, and the loss dielectric is grounded to the electromagnetic shield at a position close to the electromagnetic shield. Thus, the electromagnetic waves are effectively absorbed, and the electromagnetic waves entering from the external space or leaking to the external space via the transmission cable can be effectively suppressed.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an electromagnetic wave suppressor according to a first embodiment of the present invention.

FIG. 2 is a front sectional view taken along line AA of the electromagnetic wave suppressor shown in FIG.

FIG. 3 is an external perspective view of the electromagnetic wave suppressor shown in FIG.

FIG. 4 is a graph showing suppression characteristics of the electromagnetic wave suppressor shown in FIG. 1 with respect to electromagnetic waves.

FIG. 5 is a diagram illustrating a circuit for measuring a suppression characteristic with respect to an electromagnetic wave.

FIG. 6 is a side sectional view of an electromagnetic wave suppressor according to a second embodiment of the present invention.

FIG. 7 is a side sectional view of an electromagnetic wave suppressor according to a third embodiment of the present invention.

FIG. 8 is a side sectional view of an electromagnetic wave suppressor having a connector structure according to the present invention.

FIG. 9 is a side sectional view of another electromagnetic wave suppressor having the connector structure according to the present invention.

FIG. 10 is a graph showing suppression characteristics of a conventional ferrite clamp against electromagnetic waves.

FIG. 11 is a diagram showing a circuit for measuring the suppression characteristic of a conventional ferrite clamp against electromagnetic waves.

[Explanation of symbols]

 10, 10a, 10b, 32, 48 Electromagnetic wave suppressor 12, 12a, 12b, 44, 62 Electromagnetic shield 14, 14a, 14b, 40, 54 Transmission cable 16, 16a, 16b, 42, 56 Loss dielectric 18, 18a , 18b, 34, 52 Magnetic body 20, 20a, 36, 58 Jacket conductor 22, 22a Flange

Claims (6)

[Claims] 1. An electromagnetic wave suppressor for suppressing electromagnetic waves entering from an external space or leaking to an external space via a transmission cable disposed through an electromagnetic shield forming an electromagnetic shielding space, A magnetic body that is fitted to a part of the transmission cable, a jacket conductor that covers the magnetic body and is grounded to the electromagnetic shield, and is fitted to at least a region of the transmission cable adjacent to the magnetic body; And a loss dielectric that is grounded to the electromagnetic shield at a position close to the electromagnetic shield. 2. The transmission device according to claim 1, wherein the loss dielectric has an extended portion provided in a region of the transmission cable where the magnetic material is externally fitted, and the magnetic material is interposed through the extended material. The electromagnetic wave suppressor according to claim 1, wherein the electromagnetic wave suppressor is externally fitted to the transmission cable. 3. An extended portion having a shape covering the magnetic material is formed at one end of the lossy dielectric material, and the extended portion constitutes the outer conductor. The electromagnetic wave suppressor according to claim 1, wherein 4. The loss dielectric according to claim 2, wherein the loss dielectric is made of a flexible material.
Or the electromagnetic wave suppressor according to 3. 5. The electromagnetic wave suppressor according to claim 1, wherein the lossy dielectric has a sponge structure. 6. An electromagnetic wave suppression method for suppressing an electromagnetic wave that enters from an external space or leaks to an external space via a transmission cable disposed through an electromagnetic shield constituting an electromagnetic shielding space. A magnetic body is externally fitted to a part of the transmission cable, and a loss dielectric is externally fitted to at least a region adjacent to the magnetic body of the transmission cable, and the magnetic body is covered with a jacket conductor and the jacket conductor is covered with the sheath. An electromagnetic wave suppression method, comprising: grounding to an electromagnetic shield; and grounding the lossy dielectric to the electromagnetic shield at a position near the electromagnetic shield.