JPH04337211A - Semi-rigid coaxial cable - Google Patents

Abstract

PURPOSE:To reduce the transmission attenuation and stabilize the transmission characteristic by surrounding the outer periphery of an inner conductor with an envelope conductor layer along the longitudinal direction to form an inner conductor with a double-conductor structure in a semi-rigid coaxial cable. CONSTITUTION:An envelope conductor layer 3 is closely formed along the longitudinal direction on the outer periphery of a central conductor 2 to envelop the conductor 2, an inner conductor 4 with the inside/outside double-conductor structure is formed, a thin dielectric cover layer 5 is provided on the outer periphery as required, the outside is enveloped with a dielectric substance 6, and a metal tubular body 7 is covered on the outside to form a semi-rigid coaxial cable 1. When an SMA male connector 21 is to be provided on the cable 1, only the conductor 2 is left, a stainless male connector housing 22 is inserted and electrically connected to the metal tubular body 7, and a beryllium steel retaining ring 23 is provided. When an SMA female connector 31 is to be provided on the cable 1, a gold-plated 1 beryllium steel central connector 32 is provided on the central conductor 2, and a dielectric tube 3 is provided around it.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a semi-rigid coaxial cable, and more specifically, the present invention relates to a semi-rigid coaxial cable, which reduces transmission attenuation, reduces phase changes and capacitance changes due to temperature changes, and uses an internal conductor as a connecting pin to connect an SMA type connector. This invention relates to semi-rigid coaxial cables that can be used for applications such as semi-rigid coaxial cables.

0002

2. Description of the Related Art Conventionally, there has been a semi-rigid coaxial cable in which a dielectric material made of solid polytetrafluoroethylene resin is provided around the outer periphery of an inner conductor, and a metal tubular body serving as an outer conductor is provided around the outer periphery of this dielectric material. Semi-rigid coaxial cables are less flexible than general coaxial cables whose outer conductors are made of braided metal conductors, but they are widely used because they have the advantage of being able to transmit up to high frequency bands. For example, the US military standard MIL-C-17/130
There are semi-rigid coaxial cables specified in A. According to this standard, the diameter of the inner conductor is 0.912 mm, the diameter of the outer conductor is 3.58 mm, and the characteristic impedance is 50 Ω.

Various types of connectors are known for use with semi-rigid coaxial cables, such as the SMA male type specified in MIL-C-39012/92 for the semi-rigid coaxial cable specified in MIL-C-17/130A.・Connector construction methods in which the internal conductor of the cable also serves as the connector connection pin, such as female connectors, are superior in various respects and are recommended.

0004

[Problems to be Solved by the Invention] In this semi-rigid coaxial cable, in order to keep the diameter of the outer conductor constant, keep the characteristic impedance of 50Ω unchanged, and reduce the transmission attenuation, it is necessary to make the diameter of the outer conductor constant, for example 1. This can be achieved by using an internal conductor of about 2 mm and changing to a dielectric resin layer with a lower dielectric constant than the conventional solid polytetrafluoroethylene resin. however,
The diameter of this thickened internal conductor does not match the diameter of the receiving hole of the SMA female connector, making it unusable.Therefore, there is a problem in that such a design change is practically difficult.

One possible solution to this problem is to manufacture and use a new female connector having a receiving hole in which the thickened internal conductor after the design change is received as a connecting pin. However, it is not practical for mass production, but for small quantity production, the connector is extremely expensive. It is also conceivable to reduce the diameter of the inner conductor end portion to the standard diameter of the connecting pin by grinding it with a grinder or by pounding it to make it thinner. However, all of these methods require time and effort to process one terminal, and are not practical. Moreover, it is not preferable because it gives physical shock or scratches to the internal conductor, causing a decrease in mechanical strength and deterioration of electrical properties. Additionally, this process causes difficulties in terminal processing, such as loss of conductor plating and problems with solderability.

[0006] Furthermore, polytetrafluoroethylene resin with a rich dielectric material has a temperature range of about -55°C to +30°C.
Until then, there was a problem in that the temperature change caused extremely large phase changes and capacitance changes.

In view of these problems, the present invention uses a porous dielectric material with a low permittivity to reduce transmission attenuation, stabilize phase changes and capacitance changes due to temperature changes, and The present invention aims to provide a semi-rigid coaxial cable that can be used in SMA type connectors, etc., in which the center conductor of the SMA connector is used as a connection pin.

[0008]

[Means for Solving the Problems] The present invention has been made to achieve the above-mentioned problems, and its gist consists of an internal conductor,
In a semi-rigid coaxial cable consisting of a dielectric surrounding the inner conductor and a metal tubular body surrounding the dielectric, the inner conductor includes a center conductor, a center conductor extending longitudinally along the outer peripheral surface of the center conductor, and a metal tubular body surrounding the dielectric. The semi-rigid coaxial cable is characterized in that it has an inner and outer double conductor structure with a surrounding conductor layer closely formed to wrap around the conductor.

[0009] Another point is that the surrounding conductor layer can densely wrap one or a plurality of linear conductors or band-shaped conductors into a conductor structure such as coil winding, longitudinally spliced, cylindrical, or multi-layer conductor structure. and to provide a thin dielectric coating layer on the outer peripheral surface of the surrounding conductor layer. Note that it is preferable that the thickness of this surrounding conductor layer be one-half or less of the diameter of the center conductor. Still another feature is that the dielectric material is a porous material, an open pore material, an open pore tetrafluoroethylene resin, a foamed resin, or the like. In addition, other gist is that the metal tubular body is an oxygen-free annealed copper tubular body, an aluminum tubular body, and has a metal plating such as tin or silver plating on the outer periphery, and a resin coating on the outer periphery of the metal tubular body. It consists in providing layers.

0010

[Operation] According to the semi-rigid coaxial cable of the present invention,
The inner conductor has an inner/outer double conductor structure with the surrounding conductor layer closely formed along the outer peripheral surface of the center conductor and wrapping around the center conductor, that is, the diameter of the center conductor is increased by the surrounding conductor layer. By using a porous dielectric material with a low permittivity while keeping the diameter of the metal tubular body constant, design changes can be made without changing the characteristic impedance of the cable. Moreover, in this internal conductor, if the diameter of the center conductor is made to match the receiving hole diameter of the SMA female connector, the center conductor portion of the internal conductor can be used as a connecting pin. Therefore, for SMA type connectors, by using this center conductor as a connecting pin and using a porous dielectric with a low permittivity, it is possible to increase the internal conductor diameter without changing the cable outer diameter and characteristic impedance. , it is possible to reduce transmission attenuation with the same diameter as conventional semi-rigid coaxial cables.

[0011] In addition, this surrounding conductor layer has a conductor configuration such as one or more linear conductors or band-shaped conductors tightly wound in coils, longitudinally spliced, cylindrical, multi-layered, etc., to improve the characteristics of the cable. The impedance and shape suitable for terminal processing can be selected as appropriate. Further, in order to reduce deterioration of the electrical characteristics of the connecting portion, it is preferable that the thickness of the surrounding conductor layer is one-half or less of the diameter of the center conductor. Further, in this case, by providing a thin dielectric coating layer on the outer peripheral surface of the surrounding conductor layer, the shape of the surrounding conductor layer with respect to the center conductor can be maintained.

[0012] The dielectric material can be appropriately selected from porous materials, open-pore materials, open-pore porous tetrafluoroethylene resins, and low dielectric constant materials such as foamed resins. In particular, open-cell porous tetrafluoroethylene resin is characterized by being more stable than tetrafluoroethylene resin, with substantial phase changes and capacitance changes due to temperature changes between -55°C and +30°C. be. Especially around room temperature -55
It has been confirmed by actual measurements that it is sufficiently stable between temperatures of 120°C to 120°C.

[0013] Furthermore, the metal tubular body is an oxygen-free annealed copper tubular body or an aluminum tubular body, the outer periphery is provided with metal plating such as tin or silver plating, and the outer periphery is provided with a resin coating layer. , mechanical strength, cable weight,
We can meet all necessary items such as processability and weather resistance.

[0014]

[Embodiment] Figures 1 and 2 show a semi-rigid coaxial cable according to an embodiment of the present invention and an SMA male type cable connected to the semi-rigid coaxial cable.
FIG. 3 is a cross-sectional view of the end of the female connector. To explain this, first, the semi-rigid coaxial cable 1 has a surrounding conductor layer 3 closely formed on the outer circumferential surface of a center conductor 2 along its length so as to wrap around the center conductor 2, and an inner conductor layer 4 having a double inner and outer conductor structure. A thin dielectric coating layer 5 is provided on the outer circumferential surface of the internal conductor 4 as necessary, a dielectric 6 is surrounded on the outer circumference of the thin dielectric coating layer 5, and a metal tube-shaped It has a configuration in which the body 7 is surrounded.

[0015] This semi-rigid coaxial cable 1 has an SMA
To provide the male connector 21, first remove the ends leaving only the center conductor 2 as shown in Fig. 1, then insert the gold-plated stainless steel male connector housing 22 into it, and attach it to the metal. A conductive connection is made to the tubular body 7, and then a retaining ring 23 made of beryllium copper, a gasket 24 made of silicon, and a coupling nut 25 made of stainless steel are attached.

Furthermore, in order to provide the SMA female connector 31 to this semi-rigid coaxial cable 1, after removing the end portion leaving only the center conductor 2 as shown in FIG. a central connector 32;
The surrounding polytetrafluoroethylene dielectric tube 3
3 is provided, a female connector housing 34 made of gold-plated stainless steel is inserted into the whole, and this is electrically connected to the metal tubular body 7.

In this semi-rigid coaxial cable 1, S
Even when using an MA type connector, the center conductor 2 becomes a connection pin and can be connected to the center connector 32. Therefore, by using a low dielectric constant material such as open-cell porous tetrafluoroethylene resin or foamed resin as the dielectric material 6, the entire inner conductor 4 can be Since the diameter can be made thicker by the amount of the surrounding conductor layer 3,
The amount of transmission attenuation can be made smaller than before.

In addition, in order to reduce the deterioration of the electrical characteristics of the connection part, the thickness of the surrounding conductor layer 3 should be set to 2 times the diameter of the center conductor 2.
It is preferable to reduce the amount by 1/2 or less. In addition, the thin dielectric coating layer 5 is intended to maintain the shape of the surrounding conductor layer 3 with respect to the center conductor 2, and since it is made of a material with a higher dielectric constant than the dielectric 6, it does not affect the transmission attenuation characteristics. In order to reduce the amount, it is preferable to coat it as thinly as possible.

Furthermore, the material of this metal tubular body 7 can be varied depending on the purpose. For example, if the metal tubular body 7 is an oxygen-free annealed copper tubular body, it can be easily bent, and if the metal tubular body 7 is an aluminum tubular body, the cable weight is light, so it is suitable for use in aircraft etc. Providing metal plating such as tin or silver plating or a resin coating layer (not shown) improves solder properties and weather resistance.

Next, FIGS. 3 to 7 are perspective views of internal conductors used in the semi-rigid coaxial cable of the present invention. Note that these are diagrams explaining in detail the structure of the internal conductor 4 of the semi-rigid coaxial cable 1.

To explain these, first, FIG. 3 shows an surrounding conductor layer 3a in which one or more linear conductors 8a are tightly coiled around the outer peripheral surface of the center conductor 2a along its length;
A thin dielectric coating layer 5a provided on the outer peripheral surface of this surrounding conductor layer 3a is shown. Further, FIG. 4 shows an surrounding conductor layer 3b in which a plurality of linear conductors 8b are densely attached longitudinally along the outer peripheral surface of the center conductor 2b, and a thin dielectric layer provided on the outer peripheral surface of this surrounding conductor layer 3b. The coating layer 5b is shown. FIG. 5 also shows a surrounding conductor layer 3c that tightly wraps a single strip conductor 8c in a cylindrical shape along the length of the outer peripheral surface of the center conductor 2c, and this surrounding conductor layer 3.
A thin dielectric coating layer 5c provided on the outer peripheral surface of c is shown.

FIG. 6 also shows an surrounding conductor layer 3d in which a single band-shaped conductor 8d is tightly coiled longitudinally around the outer peripheral surface of the center conductor 2d, and a thin wall provided on the outer peripheral surface of this surrounding conductor layer 3d. A dielectric coating layer 5d is shown. Further, FIG. 7 shows an surrounding conductor layer 3e in which a strip conductor 8e and a strip conductor 8e' are tightly coiled in opposite directions along the length of the outer peripheral surface of the center conductor 2e.
and a thin dielectric coating layer 5e provided on the outer peripheral surface of this surrounding conductor layer 3e. In addition, forming the surrounding conductor layer into multiple layers as shown in Fig. 7 can be done by winding a linear conductor into a coil as shown in Fig. 3 or by wrapping a band-shaped conductor in a cylindrical shape as shown in Fig. 5. But you can.

Note that the present invention is not limited to the above-mentioned embodiments, and various changes can be made within the technical concept of the present invention, such as adjusting the dielectric constant of the dielectric material and changing the thickness of the surrounding conductor layer. Of course it is possible.

[0024]

[Effects of the Invention] As explained above, according to the present invention,
The inner conductor is a semi-rigid coaxial cable characterized by having an inner/outer double conductor structure in which a surrounding conductor layer is wrapped around the center conductor along its length on the outer circumferential surface of the center conductor. By using an internal conductor with a large diameter, the amount of transmission attenuation can be reduced, and the center conductor can be used as a connecting pin in an SMA type connector. In particular, by using a porous tetrafluoroethylene resin with open pores as the dielectric material, phase changes and capacitance changes due to temperature changes can be reduced, and transmission characteristics can be stabilized. Therefore, this semi-rigid coaxial cable is of great help in improving technology in the microwave communication field.

[Brief explanation of drawings]

[Fig. 1] A cross-sectional view of a semi-rigid coaxial cable according to an embodiment of the present invention and an end portion of an SMA male connector connected to the semi-rigid coaxial cable.

[Fig. 2] A cross-sectional view of a semi-rigid coaxial cable according to an embodiment of the present invention and an end portion of an SMA female connector connected to the semi-rigid coaxial cable.

[Figure 3] A perspective view of the internal conductor used in the semi-rigid coaxial cable of the present invention

[Fig. 4] A perspective view of another internal conductor used in the semi-rigid coaxial cable of the present invention.

FIG. 5 is a perspective view of yet another internal conductor used in the semi-rigid coaxial cable of the present invention.

[Fig. 6] Perspective views of different internal conductors used in the semi-rigid coaxial cable of the present invention.

[Fig. 7] A perspective view of yet another internal conductor used in the semi-rigid coaxial cable of the present invention.

[Explanation of symbols]

1
Semi-rigid coaxial cable 2, 2a, 2b, 2c, 2d, 2e Center conductor 3
, 3a, 3b, 3c, 3d, 3e surrounding conductor layer 4
, 4a, 4b, 4c, 4d, 4e internal conductor 5,
5a, 5b, 5c, 5d, 5e thin dielectric coating layer 6
Dielectric 7
Metal tubular bodies 8a, 8b
Linear conductors 8c, 8d, 8e, 8e'
Band-shaped conductor 21

SMA male connector 31
SMA female connector

Claims (18)

[Claims] 1. A semi-rigid coaxial cable comprising an inner conductor, a dielectric surrounding the inner conductor, and a metal tubular body surrounding the dielectric, wherein the inner conductor includes a center conductor and an outer periphery of the center conductor. The semi-rigid coaxial cable described above is characterized in that it has an inner and outer double conductor structure with an surrounding conductor layer closely formed along the longitudinal direction of the surface so as to wrap around the center conductor. 2. The surrounding conductor layer is characterized in that one or a plurality of linear conductors are densely coiled around the outer peripheral surface of the center conductor along its length.
Semi-rigid coaxial cable as described in section. 3. The surrounding conductor layer is formed by closely coiling one or more strip-shaped conductors along the length of the outer peripheral surface of the center conductor.
Semi-rigid coaxial cable as described in section. 4. The semi-rigid semiconductor device according to claim 1, wherein the surrounding conductor layer has a plurality of linear conductors closely longitudinally attached to the outer peripheral surface of the center conductor. coaxial cable. 5. The surrounding conductor layer is characterized in that a single band-shaped conductor is closely wrapped in a cylindrical shape along the length of the outer peripheral surface of the center conductor. Semi-rigid coaxial cable as described. 6. The semi-rigid coaxial cable according to claim 1, wherein the surrounding conductor layer is a plurality of layers. 7. The semi-rigid semiconductor device according to claim 1, wherein the thickness of the surrounding conductor layer is one-half or less of the diameter of the center conductor. coaxial cable. 8. The semi-rigid coaxial cable according to claim 1, further comprising a thin dielectric coating layer on the outer peripheral surface of the surrounding conductor layer. 9. The semi-rigid coaxial cable according to claim 1, wherein the dielectric is a porous material. 10. The semi-rigid coaxial cable according to claim 1, wherein the dielectric is a continuous porosity material. 11. The semi-rigid coaxial cable according to claim 1, wherein the dielectric is a porous tetrafluoroethylene resin with open pores. 12. The semi-rigid coaxial cable according to claim 1, wherein the dielectric is a foamed resin. 13. Claims 1 to 12, wherein the metal tubular body is an oxygen-free annealed copper tubular body.
A semi-rigid coaxial cable as described in any of paragraphs. 14. The semi-rigid coaxial cable according to claim 1, wherein the metal tubular body is an aluminum tubular body. 15. Claims 13 to 1, characterized in that metal plating is provided on the outer periphery of the metal tubular body.
The semi-rigid coaxial cable according to any of Item 4. 16. The semi-rigid coaxial cable according to claim 15, wherein the metal plating is tin plating. 17. The semi-rigid coaxial cable according to claim 15, wherein the metal plating is silver plating. 18. The semi-rigid coaxial cable according to claim 13, wherein a resin coating layer is provided on the outer periphery of the metal tubular body.