JP2001110253A - High frequency transfer coaxial cable and relative connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency connector capable of preventing high frequency leakage from the connections of a connector, without changing the structure of a signal carrying portion of the connector, and of prohibiting easy disassembly by connector portions. SOLUTION: The outer periphery of a connector 4 is covered with an electromagnetic wave absorber 3 extending over a cable 1 and a cable 2. The electromagnetic wave absorber 3 is formed of a flexible material, such as rubber and synthetic resin, filled with powder of magnetic material such as ferrite or metal compound. The electromagnetic wave absorber can be in a sheet or cylindrical shape, whichever. With the connector 4 and portions of the cables 1, 2 covered with the electromagnetic wave absorber 3 in such a shape, without giving any space, the possibility of leaking electromagnetic waves based on high frequency signals transferred to an internal conductor 5 to the outside is eliminated by the electromagnetic wave absorbing effect of the electromagnetic wave absorber 3 if the connection A of the connector 4 is in an incompletely connected condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-frequency transmission coaxial cable having an electromagnetic wave shielding function for preventing leakage of radio waves to the outside, and more particularly, to an electromagnetic wave around a connector of a connector used for a high-frequency transmission coaxial cable. The present invention relates to a structure of a high-frequency connector having a shielding function and a connector connection state holding function.

[0002]

2. Description of the Related Art Normally, high-frequency transmission coaxial cables (hereinafter referred to as cables) are connected to each other by high-frequency connectors (hereinafter referred to as connectors).
In addition, the connection portion of these connectors is generally of a screw type or a push-on type. FIG. 8 is a structural diagram of a conventional connector provided with a screw-type connecting portion,
(A) is an external view, (b) is a sectional view. FIG.
1 is a structural view of a conventional connector provided with a push-on type connection part, (a) is an external view, and (b) is a sectional view.
In these connectors, the continuity of the external conductor and the metal parts that form the ground at the connector connection part of the cable that transmits the radio frequency increases the shielding performance around the connector as the operating frequency of radio communication equipment becomes higher. It has a big impact.

For example, as shown in FIG. 8, a connector 31 having a threaded connection portion is composed of a male connector 32 and a female connector 33.
Are fixed by tightening the screws 34. The inner conductor 36 of the cable 35 on the male connector 32 side and the inner conductor 39 of the cable 38 on the female connector 33 side, the outer conductor 37 of the cable 35 on the male connector 32 side and the outer conductor 40 of the cable 38 on the female connector 33 side. , Respectively, maintain a conductive state. At this time, the continuity between the external conductor 37 and the external conductor 40 at the connection site of the connector 31 is affected by the strength of the screw 34 between the male connector 32 and the female connector 33. That is, the screw 34
The strength of the tightening determines the quality of the formation of the ground in the connector part, and as a result, the quality of the shielding performance is determined.

[0004] In a connector 41 having a push-on type connection portion as shown in FIG. 9, a male connector 42 and a female connector 43 are fixed by pressing a spring 44. The inner conductor 46 of the cable 45 on the male connector 42 side and the inner conductor 49 of the cable 48 on the female connector 43 side, the outer conductor 47 of the cable 45 on the male connector 42 side and the outer conductor 50 of the cable 48 on the female connector 43 side. , Respectively, maintain a conductive state. At this time, the continuity between the external conductor 47 and the external conductor 50 at the connection site of the connector 41 is affected by the strength of the pressing of the spring 44 between the male connector 42 and the female connector 43. That is, the strength of the pressing force of the spring 44 determines the quality of the formation of the ground at the connector portion, and as a result, the quality of the shielding performance is determined.

[0005]

However, in the case of the connector provided with the screw type connection portion shown in FIG. 8, when the tightening torque of the screw 34 is small, the contact between the male connector 32 and the female connector 33 is insufficient. Thus, the continuity between the external conductor 37 and the external conductor 40 is impaired, the ground potential becomes incomplete, and the shielding effect at that portion is reduced. Further, in the case of the connector having the push-on connection portion shown in FIG. 9, the contact between the male connector 42 and the female connector 43 becomes insufficient due to aging or the like due to the contact due to the pressing of the spring 44, and the external conductor 47 Continuity between the wire and the outer conductor 50 tends to be insufficient. As described above, since the continuity between the outer conductor 47 and the outer conductor 50 depends on the spring force, the ground potential is usually incomplete and the effect of the shielding performance at the connector portion is low.

FIG. 10 is a sectional view of a connector showing a portion where the shielding effect is reduced in a conventional connector.
(A) is a connector provided with a screw connection portion shown in FIG. 8,
FIG. 10B is a cross-sectional view of the connector including the push-on connection unit illustrated in FIG. 9. That is, in the case of the screw type connection part of FIG. 10A, if the screw 34 between the male connector 32 and the female connector 33 is loosely tightened, as shown in FIG. Between
Since the positions of A and B surrounded by the alternate long and short dash line are the connecting portions between them, the contact is likely to be insufficient. That is, since the continuity of the ground potential is easily lost at the positions A and B, the ground becomes incomplete, and electromagnetic waves based on signals flowing through the internal conductor leak to the outside of the connector. Therefore, if the screw 34 is loosened due to an external factor such as vibration or the screw 34 is loosened due to careless disassembly or the like, the shielding performance at the connector part is deteriorated, and the signal of the internal conductor leaks to the outside. Or the noise may enter the internal conductor from the outside, and the performance of the system device as a whole may not be maintained.

In the push-on type shown in FIG. 10B, the male connector 42 and the female connector 43 are connected to a spring 44.
, The continuity of the ground potential is fundamentally incomplete, and the shielding property at the connector part is low. Also, depending on the wiring direction of the connected cable, the connector may be chronically stressed. In such a case, the spring 44 may be distorted, which may further degrade the shielding performance. Such deterioration of the shielding performance in the connector portion not only causes a malfunction such as a malfunction in a device connected to the cable, but also causes a malfunction in other devices.

As a method for providing continuity of the ground potential in the connector section, for example, Japanese Patent Laid-Open No. 5-2111
There is a technique disclosed in Japanese Unexamined Patent Publication (Kokai) No. 1-No. According to the method disclosed in this publication, the ground potential is dropped from each of the male connector and the female connector so that the continuity of the ground potential at the connector contact portion is provided. Such a method of obtaining the ground potential can be easily implemented in a structure in which each of the male connector and the female connector is fixed to the board. However, if the cable length is long,
In the case where connectors are connected in multiple stages in the middle, it is difficult to take ground potential from both sides of the connection portion of each connector because of complicated wiring and the like. Furthermore, since discontinuity in the minute section at the connection site between the male connector and the female connector has not been eliminated,
There is leakage of electromagnetic waves from this part.

Further, in order to prevent high-frequency radiation from inside the conductor, an electromagnetic wave absorber or the like constituted by mixing a magnetic material or the like with a flexible material such as rubber is commercially available. It has been shown that if this electromagnetic wave absorber is fitted on the outer periphery of a cable or the like, a great effect can be obtained on the transmission attenuation of the electromagnetic wave radiated from the internal conductor. However, since the high frequency has a short wavelength, when a plurality of electromagnetic wave absorbers are provided continuously, a gap is generated between the electromagnetic wave absorbers, and the electromagnetic wave leaks from the gap, and the transmission attenuation effect is weakened. As a result, sufficient shielding measures cannot be taken. Furthermore, as for these electromagnetic wave absorbers, those which can correspond to the shape of each connector cannot be easily obtained.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent high-frequency leakage at a discontinuous portion of an outer conductor of a high-frequency transmission coaxial cable, and particularly to a structure of a signal conducting portion of a connector. High frequency leakage from the connection part of the connector without changing the
Another object of the present invention is to provide a high-frequency connector in which a connector portion cannot be easily disassembled.

[0011]

According to the present invention, an electromagnetic wave based on a signal transmitted to an inner conductor is formed by holding an outer conductor at a ground potential.
A high-frequency transmission coaxial cable for preventing leakage to the outside, wherein a discontinuous portion of an outer conductor is covered by a radio wave absorbing means in which a magnetic material is mixed into an organic elastic material. It is a coaxial cable.

That is, if there is a discontinuous portion in the outer conductor, this portion is not maintained at the ground potential, and there is a possibility that an electromagnetic wave based on a high-frequency signal transmitted through the inner conductor may leak to the outside. Therefore, by covering the discontinuous portion of the outer conductor with the radio wave absorbing means, there is no possibility that the electromagnetic wave based on the signal flowing through the inner conductor leaks to the outside. The radio wave absorbing means can be easily manufactured by mixing a magnetic material such as ferrite or metal powder into an organic elastic material such as rubber. Such a radio wave absorber can easily cover the coaxial cable for high-frequency transmission without gaps if the shape is a sheet shape or a cylindrical shape. Also, if one or the inner surface of the sheet-like or cylindrical-shaped radio wave absorber is provided with adhesiveness, it can be easily fixed to the coaxial cable without any gap. Alternatively, if the coaxial cable is covered with a radio wave absorber and then fixed by covering with a heat shrink tube, the radio wave absorber can be firmly fixed to the coaxial cable without any gap.

The present invention also relates to a connector for use in a high-frequency transmission coaxial cable for preventing an electromagnetic wave based on a signal transmitted to an inner conductor from leaking to the outside by holding the outer conductor at a ground potential. The connector is a high-frequency transmission connector characterized by being covered by a radio wave absorbing means in which a magnetic material is mixed into an organic elastic material.

That is, the male and female connectors are fixed by screws or springs. Therefore, the male external conductor and the female external conductor are in contact with each other due to the tightening strength of the screw and the pressing force of the spring. There may be a discontinuity in the conductor. Even in such a case, by covering the connector portion with the radio wave absorber, it is possible to prevent the radio wave based on the signal transmitted through the inner conductor from leaking to the outside. Also in this case, if the radio wave absorber is formed in a sheet shape or a cylindrical shape, the connector can be easily covered with the radio wave absorber. Furthermore, if one surface of the sheet-shaped radio wave absorber or the inner surface of the cylindrical radio wave absorber is provided with adhesiveness, the radio wave absorber can be securely fixed to the coaxial cable without any gap. Also, since the connector and the coaxial cable have different diameters, cover the connector part and a part of the coaxial cable on both sides with a radio wave absorber, then cover it with a heat-shrinkable tube and fix it. The vicinity of the boundary can be securely fixed by the radio wave absorber without any gap.

If there is a large difference between the diameter of the connector and the diameter of the coaxial cable, the sheet-shaped radio wave absorber is formed into a shape that tapers at both ends so that the connector and the coaxial cable are tapered. The coaxial cables on both sides can be covered with the radio wave absorber without gaps. Furthermore, if this is covered with a heat-shrinkable tube, the radio wave absorber can be covered more reliably without any gap. Further, by covering the connector with the radio wave absorber in this way, it is possible not only to prevent leakage of electromagnetic waves, but also to prevent the connector portion from being illegally disassembled.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Some embodiments of a high-frequency connector according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is an external view of a high-frequency connector according to the first embodiment of the present invention. FIGS. 2A and 2B are schematic structural views of the high-frequency connector according to the first embodiment of the present invention, wherein FIG. 2A is a side view and FIG.
As shown in FIG. 1, the outer periphery of a connector (not shown) for connecting the cable 1 and the cable 2 is covered with a radio wave absorber 3. That is, as shown in FIG. 2, including the connector 4, the cable 1 and the cable 2 are covered with the radio wave absorber 3. The radio wave absorber 3 is made by filling a flexible material such as rubber or synthetic resin with a magnetic material such as ferrite or a powder of a metal compound. The shape of the radio wave absorber 3 may be any of a sheet shape and a cylindrical shape.

In FIG. 2, the cross-sectional structures of the connector 4 and the cables 1 and 2 are exactly the same as those shown in FIG. That is, as shown in FIG.
The radio wave absorber 3 made as described above completely covers the connector 4 and a part of the cables 1 and 2 so that the connection state at the connection portion A of the connector 4 is incomplete. Also, due to the radio wave absorbing action of the radio wave absorber 3, there is no possibility that the electromagnetic wave based on the high frequency signal transmitted to the inner conductor 5 leaks outside. The amount of electromagnetic wave transmission attenuation and its frequency characteristics vary depending on the material, particle size and filling rate of the filler such as a magnetic material, the thickness of the sheet of the electromagnetic wave absorber 3, and so on. It is necessary to select the optimum material and sheet thickness for the frequency to be used. further,
It is necessary to arrange the radio wave absorber 3 in such a manner as to cover and cover the discontinuous portion of the connector (for example, the portion A) that causes leakage over one circumference of the connector 4. The method of fixing the radio wave absorber 3 to the connector 4 is as follows. The sheet-shaped radio wave absorber 3 is wound around the connector 4, or after the cylindrical radio wave absorber 3 is inserted into the connector 4, the outer periphery is adhered or taped. The fixation may be performed by an arbitrary method such as fixation.

FIG. 3 is a characteristic diagram showing the shielding effect of the high-frequency connector of the present invention. The horizontal axis indicates the frequency (GHz) of the signal transmitted through the internal conductor, and the vertical axis indicates the leaked reception level (dBμV). FIG. 4 is a schematic configuration diagram of a measurement system for measuring a leaked radio wave of the connector. In FIG. 4, a cable 12 is connected to a signal oscillator (SG) 11 and terminated with 50Ω. In addition, cable 1
In the vicinity of the second connector 13, a receiving antenna 14 is arranged close to measuring leaked radio waves. The receiving antenna 14 is fixed at a position where the maximum value of the leaked radio wave can be measured by moving the position near the connector 13 back and forth and left and right. In addition, the receiving antenna 14 is connected to a measuring device 16 by a wiring 15.

When the relative radiated electromagnetic fields of the conventional connector and the connector of the present invention were compared and measured by the measurement system shown in FIG. 4, the measurement results shown in FIG. 3 were obtained.
That is, as can be seen from FIG. 3, 19.49 to 19.50 GHz
In the vicinity of the frequency band, the connector of the present invention has a shielding effect of about 10 dB with respect to the connector before taking measures (that is, the conventional connector). Of course, it is possible to obtain the maximum shielding effect in a desired frequency band depending on the material mixing ratio of the filler of the radio wave absorber 3 and the thickness of the sheet.

FIG. 5 is a sectional view of the connector portion covered with a radio wave absorber when the difference between the diameter of the connector portion and the diameter of the cable is large. That is, if the difference in diameter between the connector 4 and the cables 1 and 2 is large, gaps C and D occur between the radio wave absorber 3 and the cables 1 and 2 when the radio wave absorber 3 is covered. Since the radio wave leaks at this portion, the effect of absorbing the leaked radio wave is reduced. As a countermeasure, if the sheet of the radio wave absorber 3 is lengthened in the wiring direction, the effect of radio wave absorption is improved. However, in such a method, the cost of the radio wave absorber 3 is high, so that the cost of the high-frequency connector as a whole increases. In addition, problems such as an increase in the work of fixing the radio wave absorber occur.

FIG. 6 is a diagram showing the shape of the sheet of the radio wave absorber when the difference between the diameter of the connector and the diameter of the cable is large, which is applied to the second embodiment of the present invention.
That is, according to the second embodiment of the present invention, when the difference between the diameter of the connector portion and the diameter of the cable is large, FIG.
As shown in, prepare a sheet shaped so that the thick connector part and the thin cable part can be tightly covered together, and wrap it around the connector part and the cable part. Does not occur, and the radio wave absorber can be covered in such a manner that the connector portion serving as the radiation source of the electromagnetic wave is in close contact with the connector. The shape of this sheet is such that the vicinity of the center is the outer peripheral length of the connector, and the narrowest two end portions are each formed of two leaves in a shape as shown in the figure at a half length of the outer peripheral length of the cable.

Further, as a third embodiment of the present invention,
One side of the radio wave absorber is made to be sticky, made into a seal or tape, and wrapped around the connector completely so as to completely cover and conceal the surroundings of the connector. The structure can not be decomposed. This can prevent the connector from being disassembled illegally.

Further, as a fourth embodiment of the present invention, when the sheet of the radio wave absorber has sufficient flexibility,
There is a method in which a sheet-shaped or cylindrical radio-wave absorber is used and fixed with a heat-shrinkable tube. FIG.
FIGS. 7A and 7B are cross-sectional views of a high-frequency connector when a radio wave absorber is fixed by a heat-shrinkable tube according to a fourth embodiment of the present invention, wherein FIG. It is sectional drawing after. That is, as shown in FIG. 1A, a flexible sheet-like or cylindrical electromagnetic wave absorber 2 is provided.
After covering the connector 24 and a part of the cables 21 and 22, the heat-shrinkable tube 25 is covered. At this time, since the inner diameter of the heat-shrinkable tube 25 is larger than the outer diameter of the radio wave absorber 23, the heat-shrinkable tube 25 can be easily covered. Thereafter, when the heat-shrinkable tube 25 is heated, the heat-shrinkable tube 25 contracts as shown in FIG. 3B, so that the radio wave absorber 23 can be tightly fixed. Also, by covering the periphery of the connector in such a manner, it is possible to prevent the connector from being illegally disassembled.

The embodiment described above is an example for describing the present invention, and the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the invention. is there. For example, by combining the above-described processing of the shape of the radio wave absorber sheet as shown in FIG. 6 and the fixing by the heat shrinkable tube, the radio wave absorber can be formed without particularly requiring the flexibility of the radio wave absorber sheet. It can be tightly fixed around the connector without any gap. by this,
The electromagnetic wave shielding effect can be further enhanced, and the connector portion can be configured so as not to be easily disassembled. In the above embodiment, the case where the connector portion is covered with the radio wave absorber has been described. However, the portion where the external conductor has a discontinuous portion between the coaxial cables, such as the portion connecting the coaxial cables, is subjected to radio wave absorption. Naturally, even if it is covered with a body, the effect of absorbing electromagnetic waves can be obtained similarly to the connector portion.

[0025]

As described above, according to the high-frequency connector of the present invention, it is possible to completely shield the connector and its surroundings from leakage of electromagnetic waves, and to prevent unauthorized disassembly of the connector. it can. Moreover, the high-frequency connector of the present invention can be realized only by performing simple additional processing on a conventional connector. Further, by covering the discontinuous portion of the high-frequency coaxial cable with the radio wave absorber, it is possible to prevent leakage of electromagnetic waves from the entire high-frequency coaxial cable connecting the devices. Thus, a high-frequency connector and a high-frequency coaxial cable suitable for high-frequency electronic equipment can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is an external view of a high-frequency connector according to a first embodiment of the present invention.

FIGS. 2A and 2B are schematic structural views of the high-frequency connector according to the first embodiment of the present invention, wherein FIG. 2A is a side view and FIG.

FIG. 3 is a characteristic diagram showing an electromagnetic wave shielding effect of the high-frequency connector of the present invention.

FIG. 4 is a schematic configuration diagram of a measurement system for measuring a leaked radio wave of a connector.

FIG. 5 is a cross-sectional view of the connector portion covered with a radio wave absorber when the difference between the diameter of the connector portion and the diameter of the cable is large.

FIG. 6 is a diagram illustrating a shape of a sheet of a radio wave absorber when a difference between a diameter of a connector portion and a diameter of a cable is large, which is applied to the second embodiment of the present invention.

FIGS. 7A and 7B are cross-sectional views of a high-frequency connector when a radio wave absorber is fixed by a heat-shrinkable tube according to a fourth embodiment of the present invention, wherein FIG. It is sectional drawing after contraction.

FIGS. 8A and 8B are structural views of a conventional connector provided with a screw-type connecting portion, wherein FIG. 8A is an external view and FIG. 8B is a sectional view.

FIGS. 9A and 9B are structural views of a conventional connector provided with a push-on connection portion, wherein FIG. 9A is an external view and FIG. 9B is a cross-sectional view.

FIGS. 10A and 10B are cross-sectional views illustrating a portion of the conventional connector in which the shielding effect is reduced, in which FIG. 10A is a connector provided with a screw connection portion shown in FIG. 8 and FIG. 10B is a push-on connector shown in FIG. It is sectional drawing of the connector provided with the connection part.

[Explanation of symbols]

 1, 2, 12, 21, 22 Cable 3, 23 Radio Wave Absorber 4, 13, 24 Connector 5 Inner Conductor 11 Signal Oscillator 14 Receiving Antenna 15 Wiring 16 Measuring Device 25 Heat Shrink Tube

Claims (2)

[Claims] 1. A high-frequency transmission coaxial cable for preventing an electromagnetic wave based on a signal transmitted to an inner conductor from leaking to the outside by holding the outer conductor at a ground potential. A high frequency transmission coaxial cable, wherein the coaxial cable is covered by a radio wave absorbing means in which a magnetic material is mixed into an organic elastic material. 2. A connector used for a high-frequency transmission coaxial cable for preventing an electromagnetic wave based on a signal transmitted to an inner conductor from leaking to the outside by holding the outer conductor at a ground potential. A high frequency transmission connector characterized by being covered by a radio wave absorbing means in which a magnetic material is mixed into an organic elastic material.