JP2015061215A - Wireless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication system that can maintain the aesthetic appearance and that enables stable wireless communication.SOLUTION: There is provided a wireless communication system performing communication between the outdoor and the indoor of a building. The wireless communication system comprises: a leakage coaxial cable 1 arranged outdoor, and having a linear central conductor on which a signal is propagated, an insulator covering the central conductor, an external conductor covering the insulator, and in which a plurality of slots are arranged in an axis direction of the central conductor at a certain pitch, and a sheath covering an outer periphery of the external conductor; and an antenna 20 arranged indoor, and receiving a radiation wave emitted from the plurality of slots. To the building, a window part 12 transmitting the radiation wave is provided so as to be surrounded by an outer wall 14 shielding the radiation wave. When λ denotes a wavelength of the signal, a first interval from the outer wall to the center of the central conductor separated in a vertical direction with respect to the outer wall is in a range of λ/6 or more, and a second interval from one end of the window part to the center of the central conductor separated in an opposite side direction with respect to the window part is in a range of 0.8λ or less.

Description

  The present invention relates to a wireless communication system using a leaky coaxial cable.

  A leaky coaxial cable (LCX) is one in which a plurality of slots are provided in the outer conductor of a normal coaxial cable. Through such a slot, an electromagnetic wave signal inside the cable can be emitted to the outside, or an electromagnetic wave signal outside the cable can be taken into the cable. That is, LCX is a cable type antenna and can be said to be a special long and narrow transmitting / receiving antenna.

  LCX is effective as an antenna in a place where many metal bodies exist. In places where there are a large number of metal bodies, radio wave shadows are generated by the metal bodies and an insensitive zone of radio waves is likely to occur. In such a place, if a general antenna is used, a large number of antennas must be installed. However, since each slot works as an antenna in LCX, a large number of antennas are arranged along LCX. Therefore, it is difficult to generate a dead zone even in a communication area where a large number of metal bodies exist only by laying one LCX. The laying work can be carried out very simply by simply extending the LCX, without the need to attach a general antenna individually for electrical wiring.

  As described above, the LCX is usually installed in the wireless communication area. However, recently built buildings such as offices, conference rooms, factories, and homes are newly laid out with LCX inside the building due to problems such as burden on users and deterioration of aesthetics. May be difficult. In such a case, the LCX must be installed outside the wireless communication area.

  There has been proposed a wireless communication system in which an LCX is disposed outside a building and an antenna is disposed indoors, and signals are transmitted and received between walls and windows (see Patent Documents 1 and 2).

JP 2002-152107 A JP 2004-147209 A

  However, in the wireless communication systems proposed in Patent Documents 1 and 2, when the outer wall of the building is a radio wave shield, if the LCX is installed facing the outer wall, wireless communication in the wireless communication area inside the building is not possible. Become stable. Therefore, the LCX must be arranged facing a window or the like through which radio waves are easily transmitted. As a result, aesthetic and security problems arise.

  In view of the above problems, an object of the present invention is to provide a wireless communication system that can maintain an aesthetic appearance and can perform stable wireless communication.

  According to one aspect of the present invention, there is provided a wireless communication system that performs communication between outdoors and indoors in a building, the linear center conductor that is disposed outdoors and through which a signal propagates, an insulator that covers the center conductor, An outer conductor that covers an insulator and has a plurality of slots arranged at a constant pitch along the axial direction of the central conductor, a leaky coaxial cable having a sheath that covers the outer periphery of the outer conductor, and a plurality of slots arranged indoors And an antenna for receiving the radiated radiated wave, and the building is provided with a window portion through which the radiated wave is transmitted surrounded by an outer wall that blocks the radiated wave. The second distance from the one end of the window part to the center of the center conductor spaced in the opposite direction of the window part is 0. The first distance to the center of the center conductors separated in the vertical direction is λ / 6 or more. An antenna is provided that is in the range of 8λ or less.

  In one aspect of the present invention, the longitudinal directions of the plurality of slots may be arranged at an angle inclined with respect to the axial direction, and the inclined angles of adjacent slots are angles that complement each other. May be. Alternatively, the longitudinal direction of the plurality of slots may be arranged at an angle perpendicular to the axial direction.

  According to the present invention, it is possible to provide a wireless communication system capable of maintaining aesthetics and capable of stable wireless communication.

It is the schematic which shows an example of the radio | wireless communications system which concerns on embodiment of this invention. It is the schematic which shows an example of LCX used for the radio | wireless communications system which concerns on embodiment of this invention. It is a front schematic diagram which shows an example of the measurement system of the radiated wave from LCX of the radio | wireless communications system which concerns on embodiment of this invention. FIG. 4 is a schematic side view of the measurement system shown in FIG. 3. FIG. 5 is a diagram showing a measurement result (part 1) of coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing a measurement result (No. 2) of coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing a measurement result (part 3) of coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing a measurement result (part 4) of the coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing measurement results (No. 5) of coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing measurement results (No. 6) of coupling loss by the measurement system shown in FIGS. 3 and 4. FIG. 5 is a diagram showing measurement results (No. 7) of coupling loss by the measurement system shown in FIGS. 3 and 4. It is a figure which shows the measurement result (the 8) of the coupling loss by the measurement system shown in FIG.3 and FIG.4. It is a figure which shows the measurement result (the 9) of the coupling loss by the measurement system shown in FIG.3 and FIG.4. FIG. 5 is a diagram showing a measurement result (No. 10) of coupling loss by the measurement system shown in FIGS. 3 and 4. It is a figure which shows the measurement result (the 11) of the coupling loss by the measurement system shown in FIG.3 and FIG.4. FIG. 5 is a diagram showing a measurement result (No. 12) of coupling loss by the measurement system shown in FIGS. 3 and 4. It is a table | surface which shows an example of the evaluation result of the communication state with respect to the position of LCX. It is a table | surface which shows the other example of the evaluation result of the communication state with respect to the position of LCX. It is the schematic which shows the other example of LCX used for the radio | wireless communications system which concerns on embodiment of this invention. It is the schematic which shows the other example of LCX used for the radio | wireless communications system which concerns on embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  The following embodiments of the present invention exemplify apparatuses and methods for embodying the technical idea of the present invention. The technical idea of the present invention is based on the material and shape of component parts. The structure, arrangement, etc. are not specified below. The technical idea of the present invention can be variously modified within the technical scope described in the claims.

  As shown in FIG. 1, the wireless communication system according to the embodiment of the present invention includes an LCX 1 and an antenna 20 that are installed outdoors and indoors in a building. LCX1 is a transmitting antenna, and antenna 20 is a receiving antenna. An external power supply unit 16 is connected to the LCX 1 via an approach cable 18 such as a general-purpose coaxial cable. A receiving unit 22 is connected to the antenna 20 via an approach cable 24 such as a general-purpose coaxial cable.

  In the building which is the object of the description of the embodiment, the window portion 12 is provided surrounded by the outer wall 14. The outer wall 14 of the building is made of a building material that blocks electromagnetic waves. For example, as the outer wall 14, a conductive building material such as a metal plate, a metal mesh, a reinforcing bar, or a steel frame is used. Further, as the outer wall 14, a building material containing conductive plastic may be used. The window portion 12 is made of a material that can transmit electromagnetic waves, such as glass.

  The LCX 1 is spaced from one end of the window 12 in the direction opposite to the window 12 and is spaced from the outer wall 14 in the vertical direction of the outer wall 14. An interval from the outer wall to the center of LCX1 is a first interval s, and an interval from one end of the window 12 to the center of LCX1 is a second interval d. Note that, for example, a 50Ω terminator (not shown) equal to the characteristic impedance of LCX1 may be connected to the termination of LCX1 to prevent reflection.

  As shown in FIG. 2, the LCX 1 includes a center conductor 3, an insulator 5, an outer conductor 7, and a sheath 9. The central conductor 3 extends in the axial direction (z-axis direction) from the power supply side to which the high-frequency signal is supplied toward the terminal side. The insulator 5 is provided so as to cover the central conductor 3. The outer conductor 7 is provided so as to cover the insulator 5. The sheath 9 is provided so as to cover the outer periphery of the outer conductor 7. The outer conductor 7 is provided with a plurality of slots 10a, 10b in a zigzag manner at a constant pitch P along the z-axis direction of the LCX. The slot 10a is disposed with its longitudinal direction inclined at an acute angle α with respect to the z-axis direction. The slot 10b adjacent to the slot 10a is provided with its longitudinal direction inclined at an obtuse angle β with respect to the z-axis direction. The angles α and β are complementary to each other.

  For example, the LCX 1 includes a central conductor 3 made of copper wire having a diameter of 2 mm, an insulator 5 made of polyethylene foam having a relative dielectric constant εr of 1.5 and an outer diameter of 5 mm, and an outer conductor made of copper foil having a thickness of 0.01 mm. 7 and a sheath 9 having an outer diameter of 7 mm are used. The characteristic impedance of LCX1 is 50Ω, for example. The slots 10a and 10b have a length of 12 mm, a width of 2 mm, a pitch P of 80 mm, and angles α and β with respect to the z-axis direction are 30 degrees and 150 degrees, respectively.

  The wireless communication system according to the embodiment was evaluated using the measurement system shown in FIGS. A copper conductor plate having a width Wb of 4 m and a height Hb of 3 m was installed as the outer wall 14, and a window portion 12 having a width Wa of 2 m and a height Ha of 1 m was provided at the center of the conductor plate. LCX1 having a length of 3 m was arranged in parallel to the window frame at the top of the window portion 12. The space where the LCX 1 is arranged is “outdoor”, and the space where the receiving antenna 20 is arranged is “indoor”. As coordinates of the measurement system, the center point of the window frame at the top of the window 12 is set as the origin, the x-axis is perpendicular to the outer wall 14, the y-axis is perpendicular to the window frame and above the outer wall 14, and the window frame Z-axis is set in a direction parallel to. The x and y coordinates of the center position of LCX1 are the first and second intervals s and d, respectively. The coupling loss was measured in the range of indoor coordinates x = 0 mm to −1500 mm and coordinates y = −1000 mm to 1000 mm.

A signal having an input power Pin and a frequency of 2.4 GHz is supplied from the power supply unit 16 to the power supply end of the LCX 1 via the approach cable 18. The supplied signal is emitted from LCX1. A radiated wave from the LCX 1 arranged outdoors is received by the antenna 20 such as a half-wave standard dipole antenna arranged indoors through the window portion 12. The antenna 20 is connected to a receiving unit 22 that detects a received power Pout of a radiated wave through an approach cable 24 such as a general-purpose coaxial cable. When receiving a radiation wave from the LCX 1 at the position (x, y) of the antenna 20, the antenna 20 is moved in the range of −1500 mm to 1500 mm in the z-axis direction. The average value of the received power at that time is defined as the received power Pout at the position (x, y). The coupling loss Lc representing the intensity of the radiated wave is calculated by the following equation. The smaller the coupling loss Lc, the stronger the radiation wave.

Lc = -10 log (Pout / Pin) (dB) (1)

FIG. 5 to FIG. 16 show the measurement results of the coupling loss Lc for LCX1 arranged at the second intervals d = 0 mm, 50 mm, and 100 mm at the first intervals s = 5 mm, 20 mm, 50 mm, and 100 mm, respectively. The polarization used for the measurement is Eφ polarization, which is the main radiation wave of LCX1. 5 to 7, the first interval s is 5 mm, FIGS. 8 to 10 are the first interval s 20 mm, FIGS. 11 to 13 are the first interval s 50 mm, and FIGS. 14 to 16 are the first interval s. 100 mm. 5, 8, 11, and 14, the second interval d is 0 mm, and FIGS. 6, 9, 12, and 15 are the second interval d is 50 mm, and FIGS. 7, 10, 13, and 15. 16, the second distance d is 100 mm. 5 to 16, the coupling loss distribution represented by a solid line indicates that the fluctuation in the z direction was stable within 5 dB, and the coupling loss distribution represented by a broken line has a fluctuation in the z direction exceeding 5 dB. It shows that it was unstable.

  As shown in FIGS. 5 to 16, when the LCX 1 is disposed close to the outer wall 14 or when spaced apart from the window frame of the window portion 12, the radiation wave toward the indoor side is weak. And fluctuations become severe.

  FIG. 17 is a table summarizing the communication state with respect to the position of the LCX 1 based on the measurement results shown in FIGS. The symbol shown in the table of FIG. 17 represents the communication state, ◎ is the strong and stable radiation wave intensity, ○ is stable, △ is stable in the back of the room, but from the window frame to the inner wall X is unstable in the space along, indicating that the radiation wave intensity is weak and very unstable. As shown in the table of FIG. 17, comfortable communication can be performed indoors by arranging the LCX 1 outdoors at positions where the first interval s is 20 mm or more and the second interval d is 100 mm or less.

  Next, the same measurement was performed using the measurement system shown in FIGS. 3 and 4 with the frequency of the signal being 5.2 GHz using LCX1 for the frequency of 5 GHz band. FIG. 18 is a table summarizing the communication state with respect to the position of LCX1. The symbols shown in the table of FIG. 18 are the same as those of FIG. As shown in the table of FIG. 18, when the frequency is 5.2 GHz, the LCX1 is placed indoors at a position where the first interval s is 10 mm or more and the second interval d is 50 mm or less outdoors. Communication can be performed.

  Here, the wavelengths of electromagnetic waves having frequencies of 2.4 GHz and 5.2 GHz are about 125 mm and about 58 mm, respectively. Therefore, if the wavelength of the signal supplied to LCX1 is λ, the range of stable communication states shown in the tables of FIGS. 17 and 18 is such that the first interval s is λ / 6 or more and the second interval d is 0. The range is 8λ or less.

  Electromagnetic waves have a diffractive effect, and when electromagnetic waves hit a conductive plate such as a metal, the edges of the conductive plate are bent to the inside of the plate. Therefore, as described above, if the laying position of the LCX 1, that is, the first and second intervals s and d is optimally selected, the radiated wave from the outdoor LCX 1 can be invaded indoors by the diffraction effect. As a result, there is no need for indoor installation of the LCX 1, and there is no burden of moving the user during the construction, and the indoor aesthetics can be maintained. Further, since the LCX 1 cannot be seen from the indoor, it is further preferable in terms of beauty.

  Thus, in the embodiment, the LCX 1 is laid away from the outer wall 14 above the window frame of the window portion 12 outdoors. Therefore, the aesthetics of the building can be maintained, and comfortable wireless communication can be realized in a stable communication state.

  The LCX 1 used in the radio communication system according to the embodiment is provided with slots 10a and 10b provided on the zigzag along the z-axis direction as shown in FIG. However, the slot is not limited to a zigzag slot. For example, as shown in FIG. 19, a plurality of slots 10 in which an angle γ with respect to the z-axis direction is arranged at 90 degrees may be provided in LCX1. Alternatively, as shown in FIG. 20, a plurality of slots 10 may be provided that are arranged with an inclination at the same angle γ with respect to the z-axis direction.

  Although the embodiments of the present invention have been described as described above, it should not be understood that the descriptions and drawings constituting a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art. Accordingly, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

1 ... Leaky coaxial cable (LCX)
DESCRIPTION OF SYMBOLS 3 ... Center conductor 5 ... Insulator 7 ... Outer conductor 9 ... Sheath 10, 10a, 10b ... Slot 12 ... Window part 14 ... Outer wall 16 ... Feeding part 20 ... Antenna 22 ... Reception part

Claims (4)

A wireless communication system that communicates between an outdoor and indoor building,
A linear center conductor that is disposed outdoors and propagates a signal, an insulator that covers the center conductor, covers the insulator, and a plurality of slots are arranged at a constant pitch along the axial direction of the center conductor An outer conductor, a leaky coaxial cable having a sheath covering the outer periphery of the outer conductor;
An antenna that is disposed indoors and receives radiated waves radiated from the plurality of slots;
In the building, a window portion through which the radiated wave passes is provided surrounded by an outer wall that blocks the radiated wave,
The first interval from the outer wall to the center of the central conductor spaced in the vertical direction of the outer wall is λ / 6 or more, where λ is the wavelength of the signal, and one end of the window portion is opposite to the window portion A wireless communication system, wherein a second interval to the center of the central conductor separated in the direction of is in a range of 0.8λ or less.   The wireless communication system according to claim 1, wherein longitudinal directions of the plurality of slots are arranged at an angle inclined with respect to the axial direction.   The wireless communication system according to claim 2, wherein the inclined angles of adjacent slots are complementary to each other.   The wireless communication system according to claim 1, wherein longitudinal directions of the plurality of slots are arranged at an angle perpendicular to the axial direction.

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