KR100780147B1 - A broadband leaky coaxial cable - Google Patents

Abstract

A broadband leaky coaxial cable is provided to expand a frequency bandwidth and to offer a mobile communication frequency band in an area where communication is not performed with a discrete antenna. A broadband leaky coaxial cable(100) is composed of an internal conductor(110), a dielectric body(120), an external conductor(130), a radial slot group(140), and a casing(150). The internal conductor is a conductive metallic wire. The internal conductor serves as a transmission line of an electromagnetic energy transmitted to and received from the leaky coaxial cable. The dielectric body is a dielectric layer interposed between the internal conductor and the external conductor. The dielectric body is made of a dielectric material for insulating the internal and external conductors from each other and preventing the loss of the electromagnetic wave energy. The external conductor is a conductive metallic electromagnetic wave shielding layer and is grounded by a ground wire. The casing is a plastic corrosion-protection layer for protecting the corrosion of the external conductor.

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 shows an electric field pattern of a leaky coaxial cable according to the prior art;

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

4 shows a radial slot group in accordance with a preferred embodiment of the present invention.

5 shows a main spinning slot in accordance with a preferred embodiment of the present invention.

6 illustrates an auxiliary radiating slot in accordance with a preferred embodiment of the present invention.

<Description of Major Reference Marks in Drawing>

10 ... Primary radiation slot 20 ... Secondary radiation slot

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

120 ... Dielectric 130 ... External conductor

140 ... Radiation slot group 200 ... Signal generator

The present invention relates to a wideband leaky coaxial cable, and more particularly, to a wideband leaky coaxial cable that improves the slot structure of a leaky coaxial cable to provide a high quality broadband use frequency.

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.

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.

The leakage 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.

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 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 the signal voltage is applied between the inner conductor 1 and the outer conductor 3 of the leaky coaxial cable by using the signal generator 5, electromagnetic waves are radiated through the slot 3a. Referring to the radiation pattern (radiation pattern) of the electric field with reference to 2.

As shown in FIG. 2, the radiation direction of the electromagnetic field according to the distribution of the radiation electromagnetic fields of the leaky coaxial cable forms an angle θ with the vertical axis of the leaky coaxial cable, and thus electromagnetic waves are radiated to the outside. Here, the angle θ formed between the vertical axis of the leaky coaxial cable and the traveling direction of the electromagnetic wave may radiate a uniform electromagnetic wave having a small variation in 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.

In order to more efficiently use the aforementioned leaky coaxial cable in a wireless terminal based on vertical polarization, a technique related to a vertically polarized leaky coaxial cable capable of radiating an electric field of vertical polarization has been proposed. US Patent No. 5,809,429 A leaky coaxial cable for generating vertical polarization by arranging slots in a 'c' shape is disclosed. Japanese Laid-Open Patent Publication No. 2003-273641 discloses a technique for generating vertical polarization by tilting a slot in an axial direction. Patent No. 6,292,072 discloses a technique for achieving broadband by arranging the distances between slot groups having a plurality of slots having an 'l' shape at equal intervals.

However, the leaky coaxial cable disclosed in US Pat. No. 5,809,429 is not suitable for mobile communication services in the range of 800 MHz to 2.3 GHz because the signal level is not constant, and it is difficult to achieve broadband. In addition, the technique disclosed in Japanese Patent Laid-Open No. 2003-273641 has a problem in that the horizontal polarization component is included and the characteristics are deteriorated in the tunnel. In addition, US Patent No. 6,292,072 has a problem in that the coupling loss is lowered at 200MHz or less when operating in the radiation mode at 800MHz or more.

The present invention was conceived in view of the above-described conventional problems, by improving the geometry of the slot formed in the outer conductor of the leaky coaxial cable, to provide a good use frequency at 800MHz or more, coupling loss at 200MHz or less The object is to provide this improved wideband leakage coaxial cable.

Broadband leakage coaxial cable according to the present invention for achieving the above object is a leakage coaxial cable in which electromagnetic wave (Electromagnetic Wave) is radiated to the outside atmosphere by the application of a signal voltage, the inner conductor; A dielectric surrounding the inner conductor around its center line; And a plurality of zigzag-shaped equal intervals in which radial slots are repeated along the center line so as to surround the dielectric and regularly expose a portion of the dielectric horizontally along the center line. An outer conductor; wherein the radiation slot is spaced apart from the main radiation slot having a predetermined length along a center line and a lower side of the oblique angle between the main radiation slot having a predetermined length and an obtuse angle of the main radiation slot, It characterized in that it comprises a plurality of secondary radiation slots arranged along.

Preferably, the main spinning slot has one or more times of bending so that left and right symmetry at the center in the longitudinal direction.

More preferably, the auxiliary radiating slots are arranged in plurality in parallel with the center line of the leaky coaxial cable so as to be adjacent to the lower side from one end to the other end of the main radiating slot.

In the present invention, the auxiliary radiation slots are arranged at equal intervals, the equal intervals being shorter than the length of the wavelength emitted through the auxiliary radiation slots.

According to the present invention, the frequency band used of the leaky coaxial cable satisfies the range of 75 MHz to 2.4 GHz.

Preferably, the main radiation slot operates in a radiation mode by generating a radiation wave with respect to a center line, and the auxiliary radiation slot operates in a combined mode by generating a surface wave with respect to a center line.

More preferably, the radiation wave is combined with the surface wave in the low frequency band of 200MHz or less.

Even more preferably, the radiation wave is a vertically polarized wave and the radiation slots are arranged in the same shape as neighboring radiation slots.

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 the 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 electromagnetic wave. It is a wave along the direction of travel. In addition, the plane by the wave propagation direction and the vector of an electromagnetic field is called a polarization plane. In this case, a wave in which the polarization plane is perpendicular to the ground is defined as a vertically polarized wave.

The leaky coaxial cable according to the present invention is a structure capable of radiating electromagnetic waves into the atmosphere, the structure of the leaky coaxial cable with reference to FIG.

As shown in FIG. 3, the leaky 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. Surrounding outer conductor 130, the radial slot group 140 formed in the outer conductor 130 and the outer shell 130 is composed of a compact surrounding the outer conductor (130). 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 radiation slot group 140 is formed in the outer conductor 130 so that a portion of the dielectric 120 may be regularly exposed along the center line, and electromagnetic energy is radiated through the exposed radiation slot group 140. And to be absorbed.

The radiation slot group 140 has a plurality of radiation slots (Radiation Slot) are regularly exposed horizontally along the center line, each of the radiation slots are arranged in a plurality of repeated zigzag shape, the radiation slots Are spaced apart at equal intervals and are arranged on the outer conductor 130. That is, each of the plurality of radiating slots is spaced at equal intervals and regularly arranged along the longitudinal direction based on the centerline of the leaky coaxial cable 100.

At this time, when the RF signal is applied through the signal generator 200 provided at the end of the leakage coaxial cable 100, in the direction perpendicular to the axis of the leakage coaxial cable 100 around the radiation slot group 140 An electric current flows, and an electromagnetic wave which has a polarization in the vertical direction is emitted through the radiation slot by the electric current.

In an embodiment of the present invention, each of the spinning slot is preferably arranged in a plurality of repeated zigzag shape, but is not limited thereto. For example, depending on the frequency band of the leakage coaxial cable 100, the radiating slots may be arranged at equal intervals of the same shape as the neighboring radiating slots.

Each of the spinning slots constituting the above-described spinning slot group 140 includes a main spinning slot and an auxiliary spinning slot, which will be described below with reference to FIGS. 4 to 6. 4 is a view showing a group of spinning slots according to a preferred embodiment of the present invention, Figure 5 is a view showing a main spinning slot according to a preferred embodiment of the present invention, Figure 6 is a preferred embodiment of the present invention A diagram illustrating an auxiliary radiating slot according to an example.

Referring to the drawings, each of the spinning slots are arranged in a plurality of parallel to the center line of the leaky coaxial cable, adjacent to one side of the main spinning slot 10 and the main spinning slot 10 having a predetermined length, And an auxiliary spinning slot 20.

The main spinning slot 10 is a chevron type groove having a predetermined length L from one end to the other end thereof, and is bent at least once so that the left and right sides are symmetrical in the longitudinal center of the leaky coaxial cable. In the embodiment of the present invention, the main spinning slot 10 preferably has one or more times of bending, but is not limited thereto. For example, the main spinning slot 10 may have one or more times of bending so as to be symmetrical in the center of the longitudinal direction.

More specifically, as shown in FIG. 5, the main spinning slot 10 may change the number of bending and the angle of bending to determine an optimum amount of attenuation and coupling loss. That is, the main spinning slot 10 has two bends so as to be symmetrical in the center of the longitudinal direction with respect to the centerline of the leaky coaxial cable, and the bend angle α of the main spinning slot 10 according to the bent number of times. , β) is to be 3 and 6 ° or more, respectively, based on the longitudinal axis of the leaky coaxial cable. At this time, the angle of incidence of the main radiation slot 10 is an obtuse angle.

In addition, when the RF signal is applied to the leakage coaxial cable, the main radiation slot 10 flows a current in a direction perpendicular to the central axis around the main radiation slot 10, and is perpendicular to the central axis by the current. Emits electromagnetic waves with waves in one direction.

In addition, it is preferable that the length and the equal interval of the main radiation slot 10 is a specific multiple of the length of the high frequency wavelength so as to operate in the radiation mode at a high frequency.

On the other hand, the secondary radiation slot 20 is a plurality of square grooves 21 to be provided in a predetermined length (L) of the main radiation slot 10 to be adjacent to one side forming an obtuse angle of the main radiation slot 10. 27, the square grooves 21 to 27 are arranged to be perpendicular to the longitudinal direction of the leaky coaxial cable.

In addition, when the low frequency band RF signal is applied to the leakage coaxial cable, the auxiliary radiation slot 20 generates a surface wave around the auxiliary radiation slot 20 to operate in a combined mode. At this time, it is preferable that the equal spacing P between the rectangular grooves 21 to 27 is shorter than the wavelength of the surface wave so that the equal interval P is operated in the coupling mode in the low frequency band.

Here, when the RF signal is a high frequency band, for example, 800MHz or more, the radiation wave of the main radiation slot 10 acts larger than the surface wave of the auxiliary radiation slot 20 to operate in a radiation mode without signal distortion. Meanwhile, when the RF signal is a low frequency band of 200 MHz or less, the surface wave of the auxiliary radiation slot 20 is combined with the radiation wave of the main radiation slot 10 to improve coupling loss in the low frequency band.

When a signal voltage is applied to the input terminal of the leaky coaxial cable having the above-described configuration, the electric field and the electromagnetic wave are radiated through the radiation slot, which will be described with reference to FIG. 3 again.

Referring to FIG. 3, a current flows through the inner conductor 110 and the outer conductor 130 of the leaky coaxial cable 100 by the signal generator 200, and the current flows into a radial slot group formed in the outer conductor 130. 140 changes the current distribution state.

Then, an electromagnetic field is formed around the radiation slot group 140, and an electric field is radiated through the radiation slot group 140. That is, the current energy by the signal generator 200 is converted into electric field energy and radiated to the atmosphere.

At this time, when the RF signal applied to the leakage coaxial cable 100 is a high frequency band of 800MHz to 2.4GHz, the main radiation slot included in the radiation slot group 140 acts larger than the surface wave of the auxiliary radiation slot distortion signal It operates in radiation mode without.

On the other hand, when the RF signal applied to the leakage coaxial cable 100 is a low frequency band of 200MHz or less, the surface wave of the auxiliary radiation slot is combined with the radiation wave of the main radiation slot to improve the coupling loss in the low frequency band to combine without signal distortion Operate in mode.

As mentioned above, the leaky coaxial cable is available in frequency bands covering the range of 75 MHz to 2.4 GHz. That is, a wireless terminal based on vertical polarization can be used without signal noise in a frequency band of 200 MHz or less, and can accept vertical polarization of a leaky coaxial cable in a frequency band including a range of 200 MHz to 800 MHz without deterioration of sensitivity. do.

In addition, it is easy to radiate wideband vertical polarization according to the modification of the slot structure, so DMB of 200MHz band, Cellular of 800MHz band, TRS of 850MHz band, PCS of 1.8GHz band, WCDMA of 2.0GHz band and 2.3GHz band Bidirectional communication between mobile communication terminals including WiBro is possible.

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, the present invention improves the coupling loss in the low frequency band of 200MHz or less by arranging a plurality of radiation slots consisting of a main radiation slot and a secondary radiation slot in the longitudinal direction of the outer conductor, and having 75MHz to 2.4GHz without signal noise. It has the advantage of providing a good range of broadband usage frequencies.

In addition, the frequency bandwidth can be easily extended, and the frequency band for mobile communication can be easily provided in an area where communication with a discrete antenna is not possible.

Claims (10)

In a leaky coaxial cable in which electromagnetic waves are radiated to the outside atmosphere by the application of a signal voltage, Inner conductor; A dielectric surrounding the inner conductor around its center line; And A plurality of externally arranged zigzag-like equal intervals in which radial slots are repeated along the center line so as to surround the dielectric and regularly expose a portion of the dielectric horizontally along the center line. Including; The radiation slots are spaced apart at predetermined intervals from a main radiation slot having a predetermined length along a center line and a lower side of an obtuse angle between the main radiation slots, and a plurality of auxiliary radiations arranged along the center line. And a slotted coaxial cable comprising a slot. The method of claim 1, And said main radiation slot has one or more times of bending so that left and right are symmetrical in the center of the longitudinal direction. The method of claim 2, And the auxiliary radiating slots are arranged in plurality in parallel with the center line of the leaking coaxial cable so as to be adjacent to the lower side from one end to the other end of the main radiating slot. The method of claim 3, Wherein said auxiliary radiating slots are arranged at equal intervals, said equal spacing being shorter than a length of the wavelength emitted through said auxiliary radiating slot. The method of claim 1, Broadband leakage coaxial cable, characterized in that the use frequency band of the leakage coaxial cable satisfies the range of 75MHz to 2.4GHz. The method of claim 1, And the main radiation slot operates in a radiation mode by generating a radiation wave with respect to a center line, and the auxiliary radiation slot operates in a coupled mode by generating a surface wave with respect to a center line. The method of claim 6, And the radiation wave is coupled with the surface wave in a low frequency band of 200 MHz or less. The method according to claim 6 or 7, And said radiation wave is a vertically polarized wave. The method of claim 1, The radiation slot is leaky coaxial cable for mobile communication, characterized in that arranged in the same shape as the neighboring radiation slot. The method of claim 1, Leakage coaxial cable for mobile communication, characterized in that it further comprises; an outer sheath covering the outer conductor.

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