KR100994264B1 - Leaky coaxial cable capable for adjusting resonace frequency and manufacturing thereof - Google Patents

Abstract

The present invention relates to a leaky coaxial cable capable of adjusting a resonant frequency, the leaky coaxial cable capable of emitting electromagnetic waves to the outside by applying a signal voltage, comprising: an inner conductor; A dielectric surrounding the inner conductor; An outer conductor surrounding the dielectric to provide a continuous void space in the longitudinal direction of the dielectric; An outer jacket surrounding the outer conductor; And a plurality of patches having a predetermined length size attached to the surface of the outer jacket such that the patches are positioned over the empty spaces at predetermined pitch intervals so that two adjacent patches form one slot. The resonance frequency can be changed by changing the length of the patch in the longitudinal direction without changing the shape and size of the empty space.

Leakage, Coaxial Cable, LCX, Patch, Slot, Conductor, Resonance Frequency

Description

Leaky coaxial cable capable of resonant frequency control and manufacturing method thereof

The present invention relates to a leaky coaxial cable and a method of manufacturing the same, and more particularly, to a leaky coaxial cable and a method of manufacturing the improved structure so that the resonance frequency can be changed even after the manufacture of the cable is completed.

In general, in a place where a radio frequency can not be sufficiently transmitted and received using a discrete antenna such as a tunnel, underground railway track, a building underground or an enclosed space, the transmission line and the antenna can be simultaneously operated. Leaky coaxial cable (hereinafter referred to as "LCX") is used.

The LCX emits radio waves through a plurality of slots arranged along the length of the cable. The LCX can freely design a specific frequency according to the period or shape of the slots, and it is easy to install any type of propagation shadow area.

1 is a perspective view schematically showing the configuration of the LCX according to the prior art.

Referring to FIG. 1, a conventional LCX 10 is installed to surround an inner conductor 12, a signal transmission medium of a metallic component, a dielectric 13 surrounding the inner conductor 12, and a dielectric 13. A plurality of slots 14 formed at regular intervals in the direction and having an outer conductor 15 of a metallic component connected to ground, and an outer jacket 16 covering the outer conductor 15.

In the conventional LCX 10 having such a configuration, when a certain power and a specific RF frequency are applied to one end of the cable, radio waves are leaked through the slot 14 of the outer conductor 15 formed in the longitudinal direction of the cable. Communication is possible. On the other hand, if the interval (period) between the slots 14 formed in the outer conductor 15 is adjusted, high quality communication is possible in a specific frequency band. In this frequency band, the received power and the amount of propagation are small because the direction of the radiated radio waves is designed to be close to the direction perpendicular to the axis of the cable.

However, in the case of the LCX, since the slots 14 are formed in the outer conductor 15, since the manufacturing of the LCX 10 is completed, the size or shape or the slots 14 of the respective slots 14 are typically used. You cannot change the pitch between them. This means that the cable characteristics cannot be changed after the fabrication of the cable is completed. Therefore, there is a need for a research on a cable capable of changing characteristics of a finished product.

The present invention has been made to solve the above-mentioned problems of the prior art, the structure is improved to allow the characteristics of the completed cable (change of the available band in accordance with the resonant frequency change) leakage improved adjustable resonance frequency It is an object of the present invention to provide a coaxial cable and a method of manufacturing the same.

In order to achieve the above object, the leakage coaxial cable capable of adjusting the resonance frequency according to a preferred embodiment of the present invention, the leakage coaxial cable capable of emitting electromagnetic waves to the outside by the application of a signal voltage, the inner conductor; A dielectric surrounding the inner conductor; An outer conductor surrounding the dielectric to provide a continuous void space in the longitudinal direction of the dielectric; An outer jacket surrounding the outer conductor; And a plurality of patches having a predetermined length size attached to a surface of the outer jacket such that the patches are positioned above the empty space at predetermined pitch intervals so that two adjacent patches form one slot. The resonance frequency may be changed by changing the length of the patch in the longitudinal direction without changing the shape and size of the empty space.

Preferably, the patch is substantially rectangular in shape, the long side of which is attached to the outer jacket in parallel with the longitudinal direction of the void space.

Preferably, the patch is made of copper.

In order to achieve the above object, a method of manufacturing a leaky coaxial cable according to a preferred embodiment of the present invention, (a) providing an inner conductor; (b) forming a dielectric having a predetermined thickness around the inner conductor; (c) surrounding the outer conductor around the dielectric such that a continuous void space in the longitudinal direction of the dielectric is formed; (d) surrounding the outer conductor with an outer jacket; And (e) applying a plurality of patches having a predetermined length on the surface of the outer jacket such that the patches are positioned above the void space at predetermined pitch intervals such that two adjacent patches form one slot. Attaching; includes.

Preferably, the step (c) includes inserting a hollow outer conductor having a hollow space formed in a longitudinal direction in advance to surround the dielectric.

Preferably, the step (c) includes the step of enclosing the entire outer periphery of the dielectric with the outer conductor, and then cutting off a portion of the outer conductor so that the empty space is continuously formed in the longitudinal direction.

Preferably, the step (c) includes the step of contacting a separate jig corresponding to the void space in the longitudinal direction of the dielectric to form the outer conductor on the remaining surface of the dielectric.

Preferably, the step (d) comprises the step of inserting the resultant of the step (c) into the outer jacket material in the molten state to cool.

Preferably, in the step (e), the patch of copper material is shaped to have the same radius of curvature as the outer diameter of the outer jacket and then bonded.

According to the present invention, since the coupling loss varies according to the installation place of the cable in the present invention, the patch is attached to the surface after completion of the cable to meet the conditions required to obtain the required coupling loss even after the cable is finally manufactured. These conditions can be used to adjust such conditions. That is, the present invention has the effect of actively changing the resonant frequency according to the requirements of the use frequency band of the place where the finished product is to be used after the cable fabrication.

Other objects and advantages of the present invention can be understood by the following detailed description, which will be more clearly understood by preferred embodiments of the present invention. In addition, the objects and advantages of the present invention should be understood by the structure, configuration, arrangement, arrangement, means, methods, and combinations thereof defined by the claims, but various modifications and changes may be made without departing from the spirit and scope of the present invention. It will be apparent to those skilled in the art that this is possible.

The radiation direction of the electromagnetic field according to the distribution of the radiant electromagnetic fields of the LCX forms an angle with the longitudinal axis of the LCX while electromagnetic waves are radiated to the outside. In addition, when the angle between the longitudinal axis of the LCX and the traveling direction of the electromagnetic waves is close to the vertical, uniform electromagnetic waves with less fluctuation of the signal can be radiated to the outside.

In the embodiment of the present invention, the electromagnetic wave is a radio wave according to the direction of wave propagation due to the interaction of an electric field and a magnetic field, and the polarized wave means a wave along the direction of propagation of the electromagnetic wave. In addition, the plane by the wave propagation direction and the vector of an electromagnetic field is called a polarization plane. Here, a wave in which the polarization plane is perpendicular to the ground is defined as vertical polarization. LCX according to the present invention is a structure capable of radiating electromagnetic waves into the atmosphere.

Hereinafter, a leakage coaxial cable capable of adjusting a resonance frequency according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is an exploded perspective view of a leaky coaxial cable capable of adjusting the resonant frequency according to a preferred embodiment of the present invention, Figure 3 is a plan view of a leaky coaxial cable according to a preferred embodiment of the present invention.

2 and 3, the leaky coaxial cable 100 surrounds the inner conductor 110, the dielectric 120 and the dielectric 120 that are compactly wrapped about the inner conductor 110, but the dielectric 120 The outer conductor 130 and the outer conductor 130 having a predetermined depth and spacing in the longitudinal direction of the 120 and forming an empty space 132 for forming the slots 134 in the completed cable are compactly formed. A plurality of predetermined shapes attached to the surrounding outer jacket 140 and the surface of the outer jacket 140 of the finished product so as to cover the empty space 132 in a state surrounded by the outer jacket 140. With a patch 150.

The inner conductor 110 is, for example, a conductive wire made of a metal in which a copper tube, a copper wire, or a copper aluminum wire may be selectively adopted, and a transmission path for electromagnetic energy transmitted and received through the LCX 100. Function of.

The dielectric 120 is a dielectric layer interposed between the inner conductor 110 and the outer conductor 130, so as to insulate between the inner conductor 110 and the outer conductor 130 to prevent loss of electromagnetic wave energy. For example, foamed plastics or plastic composite insulators are constructed of conventional dielectric materials that can optionally be employed.

The outer conductor 130 is made of a conductive metal material, for example, a copper tube or a laminated aluminum tape can be selectively adopted, and is grounded by a ground line (not shown) as a shielding layer of electromagnetic waves. The outer conductor 130 is compactly enclosed around the dielectric 120 such that a continuous empty space 132 is provided in the longitudinal direction of the dielectric 120. The void 132 is for forming the slot 134 for the spinning of the cable with the patches 150 after the cable is completed. Accordingly, the circumferential distance D of the empty space 132 is equal to the length Ds of the slot 134 of the final product, and the depth of the empty space 132 is equal to the thickness of the outer conductor 130.

The outer jacket 140 is an outer shell of the LCX 100 and functions as a corrosion preventing layer for preventing corrosion of the outer conductor 130 and is made of a plastic material.

The patch 150 is preferably in the form of a piece of copper having a substantially rectangular shape and a predetermined thickness. Each of the patches 150 is attached to the outer jacket 140 such that its long side P _L is parallel to the longitudinal direction of the empty space 132. Each patch 150 is external so that the patches 150 are positioned over the empty space 132 at a predetermined pitch P so that two adjacent patches 150 can form a slot 134. It is attached to the surface of the jacket 140. To this end, each patch 150 has a predetermined length (long side) P _L and a short side P _{S that} can sufficiently cover the empty space 132.

As shown in FIG. 4, the short side 151 of the left patch 150a and the short side 153 of the right patch 150b become the length Ds of the slot 134 of the cable, and the left and right patches 150a. The interval Db of the loop 150b becomes the short side of the slot 134.

The patch 150 according to the present embodiment resonates by changing the longitudinal size P _L of the patches 150 without changing the shape and size of the empty space 132 in the finally completed cable. This is to allow the frequency to be changed. This is because the patch 150 operates as a half-wave resonant antenna, so that the resonance band can be adjusted by adjusting the length of the periodic patch.

The voids 132 of the outer conductor 130 and the slots 134 formed by the patches 150 are regularly exposed vertically in the longitudinal direction along the centerline of the cable. Accordingly, when the RF signal is applied through a signal generator (not shown) provided at the end of the LCX 100, the current flows in the longitudinal direction of the LCX in a direction substantially perpendicular to the current through the slots 134. Electromagnetic waves with polarization are emitted. In addition, the spacing of the patches 150 may be adjusted according to the frequency band of the LCX 100 used.

Referring to the manufacturing method of LCX according to a preferred embodiment of the present invention.

First, for example, a conductive inner conductor 110 made of a metal in which a copper tube, an interlocking wire, or a copper aluminum wire may be selectively adopted is prepared.

Next, a dielectric 120 comprising a conventional dielectric material, for example, a foamed plastic or plastic composite insulating material can be selectively employed, is compactly wrapped around the inner conductor 110.

Subsequently, using the outer conductor 130 made of a conductive metal material, for example, a copper tube or a laminated aluminum tape or the like may be selectively employed, the hollow space 132 continuous in the longitudinal direction of the dielectric 120 is formed. It is compactly wrapped around the dielectric 120 to be provided.

In this process, it is preferable that the outer conductor 130 is inserted so as to surround the dielectric 120 having an empty space formed first in the longitudinal direction. The outer conductor 130 has a flat shape on a thin sheet, and an empty space is formed by punching or cutting before surrounding the dielectric 120.

Alternatively, the entire circumference of the dielectric 120 may be surrounded by the outer conductor 130, and then the empty space 132 may be continuously formed in the longitudinal direction of the cable. This process may use a method such as cutting or melting a portion of the outer conductor 130. As another alternative, a separate jig (not shown) corresponding to the empty space 132 is first contacted in the longitudinal direction of the dielectric 120 and then surrounds the outer conductor 130 on the remaining surface of the dielectric 120. You can also use the method.

Next, in a state in which the outer conductor 130 is formed, the outer jacket 140 including the plastic material is wrapped. This process takes a manner of cooling by inserting the cable into the outer jacket material in the molten state, similar to a conventional cable manufacturing method. Alternatively, the hollow plastic outer jacket 140 may be separately prepared and then inserted into the outer jacket 140 an intermediate product including the outer conductor 130, or simply wrapped or foamed with the plastic surface of the intermediate product. It may also be implemented in such a way as to apply.

Finally, the surface of the outer jacket 140 is positioned such that the patches 150 are positioned over the empty space 132 at predetermined pitch intervals so that two adjacent patches 150 may each form a slot 134. A plurality of patches 150 having a predetermined length size are attached. Here, each of the patches 150 is preferably prepared in advance to have a radius of curvature substantially the same as the outer diameter of the outer jacket 140.

The patch 150 attached to the outer jacket 140 and the resonance frequency have the following relationship.

Where f is the resonant frequency, c is the speed of light in vacuum, ε _r is the permittivity of the outer jacket, and L is the length of the patch in the longitudinal direction, respectively.

Table 1 shows a comparison between the resonant frequency calculated based on the relational expression and the resonant frequency analyzed using the electromagnetic analysis program.

As confirmed by Table 1, it can be seen that the calculated value and the analyzed value are almost the same.

5 shows the attenuation of the LCX analyzed using the analysis program, and shows that the resonant frequency changes as the size of the patch increases to 190 mm, 290 mm, and 390 mm, respectively.

The following drawings attached to this specification are merely illustrative of the preferred embodiments of the present invention, and together with the description of the present invention to serve to more clearly understand the technical spirit of the present invention, the present invention It should not be interpreted to be limited to the content described in such drawings.

1 is a perspective view showing the configuration of a leaky coaxial cable according to the prior art.

2 is an exploded perspective view schematically showing the structure of a leaky coaxial cable according to a preferred embodiment of the present invention.

3 is a plan view schematically showing the structure of a leaky coaxial cable according to a preferred embodiment of the present invention.

4 is an enlarged view illustrating a slot portion of FIG. 3.

5 is a graph showing a change in the resonance frequency according to the size change of the patch of the leaky coaxial cable according to an embodiment of the present invention.

Claims (8)

In a leaky coaxial cable capable of emitting electromagnetic waves to the outside by applying a signal voltage, Inner conductor; A dielectric surrounding the inner conductor; An outer conductor surrounding the dielectric to provide a continuous void space in the longitudinal direction of the dielectric; An outer jacket surrounding the outer conductor; And And a plurality of patches having a predetermined longitudinal size attached to a surface of the outer jacket such that the patches are positioned over the empty space at predetermined pitch intervals so that two adjacent patches form one slot. , The resonant frequency adjustable leakage coaxial cable, characterized in that the resonant frequency can be changed by changing the longitudinal size of the patch without changing the shape and size of the empty space. The method of claim 1, And said patch is substantially rectangular in shape and its long sides are attached to said outer jacket in parallel with the longitudinal direction of said void space. The method of claim 1, Leakage coaxial cable capable of adjusting the resonant frequency, characterized in that the material of the patch copper. (a) providing an inner conductor; (b) forming a dielectric having a predetermined thickness around the inner conductor; (c) surrounding the outer conductor around the dielectric such that a continuous void space in the longitudinal direction of the dielectric is formed; (d) surrounding the outer conductor with an outer jacket; And (e) attaching a plurality of patches of predetermined length to the surface of the outer jacket such that the patches are positioned above the void space at predetermined pitch intervals so that two adjacent patches form one slot. Method of manufacturing a leaky coaxial cable capable of adjusting the resonant frequency, characterized in that it comprises a. In claim 4, The step (c) comprises the step of inserting a hollow outer conductor having a hollow space formed in the longitudinal direction in advance to wrap around the dielectric, characterized in that the resonant frequency controllable coaxial cable manufacturing method. In claim 4, The step (c) includes the step of contacting the separate jig corresponding to the empty space in the longitudinal direction of the dielectric and forming the outer conductor on the remaining surface of the dielectric, it is possible to adjust the resonance frequency Method of manufacturing leakage coaxial cable. In claim 4, The step (d) is a method of manufacturing a leakage coaxial cable capable of adjusting the resonant frequency, characterized in that it comprises the step of inserting and cooling the resultant of the step (c) to the outer jacket material in the molten state. In claim 4, In the step (e), the patch of copper material is formed to have a radius of curvature equal to the outer diameter of the outer jacket and then bonded to the resonant frequency control method of manufacturing a leaky coaxial cable, characterized in that the bonding.

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