KR100817981B1 - A broadband leaky coaxial cable - Google Patents

Abstract

A broadband leaky coaxial cable is provided regularly to arrange a plurality of irradiation slots in a zigzag pattern according to a lengthwise direction of an external conductor and specializing lengths and cycles of the irradiation slot. A broadband leaky coaxial cable(100) includes an internal conductor(110), a dielectric body(120), an external conductor(130), irradiation slots(140), and an outer coat(150). The dielectric body compactly covers the internal conductor. The external conductor compactly covers the dielectric body. The dielectric body, the external conductor, and the outer coat are concentrically stacked on the internal conductor in sequence. The internal conductor is a conductive metallic wire. The internal conductor is a transmission line of electromagnetic wave energy transmitted/received from/in the leaky coaxial cable. The dielectric body is interposed between the internal conductor and the external conductor and insulates between the internal and external conductors.

Description

A broadband leaky coaxial cable

The following drawings, which are attached to this specification, illustrate exemplary embodiments of the present invention, and together with the detailed description of the present invention, serve to further understand the technical spirit of the present invention. It should not be construed as limited to.

1 is a perspective view schematically showing the structure of a leaky coaxial cable according to the prior art;

2 is a diagram showing an electric field reflection angle of a leaky coaxial cable according to the prior art.

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

4 illustrates an arrangement of radiating slots in accordance with a preferred embodiment of the present invention.

FIG. 5 is a diagram showing electric field patterns for horizontal polarization in radiation mode conversion according to a preferred embodiment of the present invention. FIG.

FIG. 6 shows electric field patterns for circular polarization in radiation mode conversion according to a preferred embodiment of the present invention. FIG.

FIG. 7 illustrates electric field patterns for vertical polarization in radiation mode conversion according to a preferred embodiment of the present invention. FIG.

<Description of Major Reference Marks in Drawing>

100 ... Leakage coaxial cable 110 ... Inner conductor

120 ... Dielectric 130 ... External conductor

140 ... radiation slots 141, 142 ... first and second slot

150 ... shell 200 ... signal generator

The present invention relates to a wideband leaky coaxial cable, and more particularly, to provide a wideband leaky coaxial cable capable of coping with various frequency bands by improving the slot structure of the leaky coaxial cable.

Generally, a leaky coaxial cable (Leaky Coaxial) is used in a place where a radio frequency (hereinafter referred to as RF) cannot be sufficiently transmitted and received by a discrete antenna such as a tunnel, underground railway, underground building, and an enclosed space. Cable) is used. Here, the leaky coaxial cable serves as a transmission line and an antenna at the same time.

Leakage coaxial cable is a cable that allows radio waves to be radiated through a plurality of slots provided along a longitudinal direction, and can freely design characteristic frequencies by adjusting slot periods or shapes, and shading radio waves of any shape. It is easy to lay in the area.

The structure and electric field pattern of the aforementioned leaky coaxial cable will be described with reference to FIG. 1.

As shown in FIG. 1, the leaky coaxial cable 10 comprises an inner conductor 1, an insulator 2, an outer conductor 3 and an outer sheath 4 from the center. Here, the outer conductor 3 is perpendicular to the longitudinal direction and forms slots 3a spaced at regular intervals. The slot 3a is a rectangular groove having a predetermined length.

When a signal voltage is applied between the inner conductor 1 and the outer conductor 3 of the leaky coaxial cable 10 by using the signal generator 20, electromagnetic waves are radiated through the slot 3a. The radiation pattern of the electric field will be described with reference to FIG. 2.

As shown in FIG. 2, the radiation direction of the electromagnetic field according to the distribution of the radiated electromagnetic field of the leaky coaxial cable 10 forms a predetermined angle θ with the vertical axis of the leaky coaxial cable 10, whereby electromagnetic waves radiate to the outside. do. Here, the angle θ formed between the vertical axis of the leaky coaxial cable 10 and the traveling direction of the electromagnetic wave may radiate a uniform electromagnetic wave having a small fluctuation of a signal when approaching zero. On the other hand, the radiation angle and the single-mode frequency band can be adjusted according to the pitch p between the slots 3a, and outside of this band, signal distortion occurs by the second to Nth harmonic modes.

These leaky coaxial cables could only be used in the FM, Pager, and Cellular bands. However, as mobile services have recently evolved to broadband frequencies, leaky coaxial cables for wideband RF (e.g., RFCX and RFCL) can carry up to the UHF band. Is being used.

In addition, the leaky coaxial cable for wideband RF is designed to form a radiation mode corresponding to various frequency bands, and is applied to a system capable of communicating with a central control station or an external base station. Here, the above-described system uses a bandwidth including up-link and down-link frequency ranges, that is, frequency bandwidths in the forward and reverse directions.

However, the conventional leaky coaxial cable emits a single mode polarization, but is designed to be used regardless of the kind of polarization according to various frequencies and frequencies, and thus it is difficult to cope with communication environments in various frequency ranges.

That is, a conventional leaky coaxial cable is designed for use in a wide frequency range, but emits a single mode polarization, so that the FM communication in the 75MHz to 210MHz band based on any one selected from vertical polarization, horizontal polarization and circular polarization and It is difficult to efficiently cope with TDMB communication, FRS communication in 450MHz band, and TRS communication in 806-866MHz band, and the combined loss value of the entire frequency band is poor, and it significantly reduces the transmission and reception sensitivity according to the polarization type. There is a problem.

In addition, the conventional leaky coaxial cable has a structure capable of bidirectional communication in various frequency bands, or because the distance from the mobile terminal has a communication restriction, there is a problem that can not communicate with the terminal over a certain distance.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and improves the geometry of the slots formed in the outer conductor of a leaky coaxial cable, thereby reversing the bidirectional broadband regardless of the type of polarization in various communication environments according to frequency bands. The object is to provide a wideband leakage coaxial cable capable of communication.

A wideband leakage coaxial cable according to the present invention for achieving the above object, the leakage coaxial cable having a predetermined frequency band is radiated to the outside atmosphere by the application of a signal voltage, the inner conductor; A dielectric covering the inner conductor compactly with a center line; And an outer conductor in which a plurality of radiating slots having a predetermined length are arranged at equal intervals so as to surround the dielectric compactly and expose a portion of the dielectric in a repeated zigzag pattern along a center line. The polarization radiated through the slot is converted into a circular mode, a horizontal polarization and a vertical polarization according to the frequency band, and the slot period between the radiation slots is characterized in that it satisfies a range of 85 to 95 mm.

Preferably, the slot period is a straight length in the centerline direction including the radial slot and the equal interval, the length of the slot is smaller than the slot period.

In the present invention, a vertical polarization is emitted when the ratio (λ / L) of the length (λ) of the polarization radiated through the radiation slot (L) is less than 5, and the circular polarization is greater than 5 and less than 20 Polarization is emitted, and if it exceeds 20, horizontal polarization is emitted.

Preferably, the frequency band satisfies a range of 75 to 866 MHz.

According to the invention, the outer cover for covering the outer conductor; further comprises.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the present specification and claims should not be construed as being limited to the common or dictionary meanings, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, which can be replaced at the time of the present application It should be understood that there may be various equivalents and variations.

In an embodiment of the present invention, the electromagnetic wave is an electric wave according to the direction in which the wave proceeds due to the interaction of the electric field and the magnetic field, and the polarization is the progression of the electromagnetic wave. It is a wave along the direction. In addition, the plane by the wave propagation direction and the vector of an electromagnetic field is called a polarization plane.

In this case, the wave perpendicular to the earth is defined as a vertically polarized wave, and the wave horizontal to the earth is defined as a horizontally polarized wave, and the trajectory of the end of the electric field vector is defined as a circle. The resulting wave is defined as a circular polarized wave.

The leaky coaxial cable according to the present invention is a structure capable of radiating vertical polarization, circular polarization, and horizontal polarization to the atmosphere, and the structure of the leaky coaxial cable will be described with reference to FIGS. 3 and 4.

As shown in FIG. 3, the leakage coaxial cable 100 includes an inner conductor 110, a dielectric 120 that compactly surrounds the inner conductor 110 with a center line, and the dielectric 120 compactly. It consists of an outer conductor 130, a radiation slot 140 formed in the outer conductor 130 and a shell 150 surrounding the outer conductor 130 compactly. In this case, the dielectric 120, the outer conductor 130, and the outer shell 150 are sequentially stacked concentrically on the inner conductor 110.

The inner conductor 110 is a conductive wire of a metallic material. As the metal material, a copper tube, an interlocking wire, or a copper aluminum wire may be selectively adopted. The metal material is a transmission line of electromagnetic wave energy transmitted and received on the leaky coaxial cable 100.

The dielectric 120 is a dielectric layer interposed between the inner conductor 110 and the outer conductor 120 to insulate between the inner and outer conductors 110 and 130 and to prevent loss of electromagnetic wave energy. As the dielectric material, a foamed plastic or a plastic composite insulator is selectively adopted.

The outer conductor 130 is grounded by a ground wire as an electromagnetic shielding layer made of a conductive metal material. As the metal material, a copper tube or a laminated aluminum tape may be selectively adopted.

The outer shell 150 is a corrosion protection layer of a plastic material to prevent corrosion of the outer conductor 130.

In this case, a plurality of radiation slots 140 are formed in the outer conductor 130 so that a part of the dielectric body 120 may be exposed in a regular zigzag pattern along the center line, and the exposed radiation slots 140 may be exposed. ) Allows electromagnetic energy to be radiated and absorbed.

As shown in FIG. 4, the radiation slot 140 is arranged along a center line in a zigzag pattern. The zigzag pattern includes a first slot 141 inclined at a predetermined angle α with the center line, and the first slot 141. A plurality of second slots 142 spaced apart from one slot 141 at predetermined intervals and inclined at a predetermined angle (−α) are repeatedly arranged along the center line.

In an embodiment of the present invention, when a signal voltage is applied to the input terminal of the leaky coaxial cable 100 using the signal generator 200, an electric field and electromagnetic waves are radiated through the radiation slot 140. That is, current flows through the inner conductor 110 and the outer conductor 130 of the leaky coaxial cable 100 by the signal voltage, and the current is caused by a plurality of radiating slots 140 arranged in the outer conductor 130. The current distribution changes and polarization is radiated outward.

In this case, the polarization radiated through the radiation slot 140 may be converted into a vertical polarization, a circular polarization, and a horizontal polarization according to the frequency band applied by the signal generator 200. The slot period of the radiation slot 140 and the length of the radiation slot 140 are designed so that the attenuation amount does not decrease in correspondence to the polarization of the.

Specifically, the slot period P of the radiation slot 140 and the length L of the radiation slot 140 is a good amount of attenuation in consideration of the resonance point of the radiation frequency in the frequency band including the range of 75MHz to 866MHz. It is designed to obtain a, the slot period (P) of the spinning slot 140 satisfies the range of 85 to 95mm in a straight line length in the center line direction including the spacing slot 140 and the equal interval, and the spinning slot The length L of satisfies a range smaller than the slot period P.

In addition, since the polarization radiated through the radiation slot 140 is converted into a vertical, circular and horizontal polarization mode as shown in FIGS. 5 to 7 according to the frequency band, the polarization radiated through the radiation slot 140 By adjusting the ratio (λ / L) of the polarization length ([lambda] [m]) and the radiation slot length (L [m]), each polarization along the frequency band can provide a good transmission / reception rate without signal distortion. Make sure That is, vertical polarization is emitted when the ratio (λ / L) is less than 5, circular polarization is emitted when more than 5 and less than 20, and horizontal polarization is emitted when it exceeds 20.

The leaky coaxial cable that satisfies the length, period, and arrangement of the above-mentioned radiation slots has different polarizations depending on the frequency used, so that FMs in the 75 MHz to 210 MHz band based on any one of vertical polarization, horizontal polarization and circular polarization are selected. Communication and TDMB communication, FRS communication in the 450 MHz band, and TRS communication in the 806 to 866 MHz band are respectively efficiently supported. That is, in the frequency band including the range of 750 to 866 MHz, the coupling loss value can provide a good transmission / reception sensitivity regardless of the type of polarization. For example, when the radiating slot length L of the leaky coaxial cable is 0.08 m and the length λ of the polarization radiated from the radiating slot is 0.7 m, the ratio λ / L becomes 8 to form a circular polarization. Good transmission and reception sensitivity can be obtained in FRS communication in the 450 MHz band.

Although the present invention has been described above by means of limited embodiments and drawings, the present invention is not limited thereto and will be described below by the person skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of the claims.

As described above, in the present invention, a plurality of radiating slots are regularly arranged in a zigzag pattern along the longitudinal direction of the outer conductor, and the length and period of the radiating slots are specified, so that good communication is performed regardless of the type of polarization according to the frequency band. There is an effect that can provide sensitivity.

In addition, by mode switching below the TRS frequency band using the 75 to 866 MHz band, it is possible to broadband communication of the terminal used for the FM, TDMB, FRS and TRS communication.

Claims (7)

In a leaky coaxial cable in which polarization having a predetermined frequency band is radiated to the outside atmosphere by application of a signal voltage, Inner conductor; A dielectric covering the inner conductor compactly with a center line; And And a plurality of outer conductors having a plurality of radial slots arranged at equal intervals so as to surround the dielectric compactly and expose a portion of the dielectric in a repeated zigzag pattern along a center line. Polarization radiated through the radiation slot is radiation mode converted into circular polarization, horizontal polarization and vertical polarization according to the frequency band, And the slot period between the radiating slots satisfies a range of 85 to 95 mm. delete The method of claim 1, And said slot period is a straight line length in the centerline direction including a radial slot and an equal interval. The method of claim 1, And the length of the radiating slot is less than the slot period. The method of claim 4, wherein If the ratio (λ / L) of the length (λ) of the polarization radiated through the radiation slot (λ) is less than 5, the vertical polarization is emitted, if more than 5 and less than 20 circular polarization is emitted, Broadband leakage coaxial cable, characterized in that horizontal polarization is emitted above 20. The method of claim 5, And said frequency band satisfies a range of 75 to 866 MHz. The method of claim 1, And a sheath covering the outer conductor.

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