JP5005229B2 - Bidirectional beam antenna and transmission system - Google Patents

Description

  The present invention relates to a bidirectional beam antenna and transmission system that require a long service area in the longitudinal direction, and more particularly to a bidirectional beam antenna and transmission system used for communication between a train or a car and a railway line.

  Conventionally, in mobile wireless communication performed between a train moving on a railroad track and a station, a command center, etc., a plurality of ground stations are provided at predetermined intervals along the railroad track, and a predetermined ground station is set by a control station. The wireless communication with the train is selected (for example, refer to Patent Document 1).

  In the ground station, a bidirectional beam antenna is used so that wireless communication can be performed from any direction in front of and behind the train. In the conventional bidirectional beam antenna, in order to achieve bidirectional directivity, two unidirectional directivity Yagi antennas 11 and 12 are used as shown in FIG. It is attached by. In this case, the Yagi antennas 11 and 12 are set so that the plane of polarization is vertical polarization, and the directivity direction is along the line direction and opposite to each other. In addition, a two-distributor 15 is attached to the support column 13, and a signal from a transmitter / receiver (not shown) is divided into two to feed the Yagi antennas 11 and 12 in-phase.

  FIG. 20 shows a case in which eight Yagi antennas 11 and 12 are used and six waveguide elements are provided in front of the main feeding element and one reflecting element is provided behind. FIG. 21 shows the vertical polarization horizontal plane directivity in the 400 MHz band of the bidirectional beam antenna configured using the eight-element Yagi antennas 11 and 12 as described above.

  Conventionally, for example, in order to configure a wireless LAN between a train or an automobile and a railway line, an omnidirectional antenna is used, or a beam antenna such as a Yagi antenna is used. However, omnidirectional antennas often have a 2.4 GHz or 5 GHz band for radio waves used in wireless LAN, and are susceptible to the influence of reflected waves (multipath) due to the landforms of buildings and buildings. is there. In particular, there are many problems in metropolitan areas where there are many structures along the railway line, and it is necessary to make effective use of radio waves without emitting radio waves in unnecessary directions.

  Also, a beam antenna using a bar-shaped element such as a Yagi antenna has high directivity in one direction but does not have directivity in the opposite direction. To configure a wireless LAN along the railway line, two antennas are required as shown in FIG. However, when two antennas are provided, there is a problem of mutual interference, and it is not preferable to install the antennas on the same axis.

  Furthermore, as one method for preventing a decrease in transmission speed, there is a space diversity system in which a plurality of transmission / reception antennas are arranged at appropriate intervals. However, the conventional method has a large number of equipment and a complicated configuration. There was also a problem of becoming.

  Conventionally, a directivity control antenna that switches between two antennas has been proposed in order to bias the directivity in a desired direction (see, for example, Patent Document 2). However, the present invention cannot be transmitted in both directions at the same time, and is not a method suitable for a wireless LAN configuration between a train or the like that requires high directivity with respect to the backward direction and along the line.

  As another invention for controlling directivity, an antenna that combines two antennas to ensure uniform directivity or enhance directivity in an arbitrary direction has been proposed (for example, Patent Document 3). reference.). However, the present invention aims to eliminate the direction of low gain in a wide service area, and does not secure a long service area for bi-directional purposes of the present invention.

As another invention, an invention in which two patch antennas are arranged on the front and back sides has been proposed (see, for example, Patent Document 4). However, the present invention does not have a configuration that specializes in the longitudinal direction and realizes high directivity, and aims to realize circular polarization with omnidirectionality in a horizontal plane.
JP-A-6-224811 Japanese Patent Laid-Open No. 2004-7532 JP 2001-36340 A Japanese Patent Laid-Open No. 9-219618

  In the conventional bidirectional beam antenna, two Yagi-type antennas 11 and 12 are attached to the support column 13 by the mounting brackets 14a and 14b and the 2-distributor 15 is attached to the support column 13 in order to achieve bidirectional directivity. Therefore, when installing the antenna, assembly on site is required, and due to electrical restrictions, the predetermined mounting dimensions, that is, the positional relationship between the antennas 11 and 12 and the support columns 13 and the antennas 11 and 12 are detailed. Since construction with adjustment is necessary, there are problems in that it is difficult to increase construction costs and secure desired electrical characteristics.

  Further, when the bidirectional beam antenna is configured by combining the Yagi antennas 11 and 12, a large side lobe is generated as shown in the directivity of FIG. There were problems of interference and poor efficiency.

  The present invention has been made to solve the above-described problems, eliminates the need for on-site assembly and adjustment, realizes stabilization of electric characteristics and cost reduction, and realizes further reduction of side lobes. An object of the present invention is to provide a bidirectional beam antenna.

  In addition, the present invention provides a directivity in both the front and back directions in order to construct a communication network between a train or automobile and a railway line that requires a long service area in the longitudinal direction but does not require directivity in the lateral direction. It is an object of the present invention to provide a bidirectional beam antenna having

  In addition, the present invention provides a bidirectional beam antenna that can store a patch antenna in a compact housing and can be mounted on a train or a car, and further facilitates the adoption of a space diversity system and further improves transmission quality. And a transmission system.

The bidirectional beam antenna according to the first aspect of the present invention is gradually reduced in size toward the distal end and a mounting portion provided with a mounting mechanism for mounting on another support member, and patch antennas provided on both sides of the mounting portion. A first and a second directional antenna unit combined with a multistage parasitic element; and a distributor that is provided in the attachment unit and feeds power to the first and second directional antenna units. It is characterized by.

In the bidirectional beam antenna according to the second invention, two patch antennas having a unidirectional characteristic having a radiation element composed of a radiation plate and a ground plate are coaxially arranged in communication with a train or an automobile along a railway line. together back to back to be disposed, anti skill radio mutual interference in each patch antenna by the ground plate, and, and forming the same cylindrical directivity around device.

According to a third aspect of the present invention, in the bidirectional beam antenna according to the first aspect of the present invention, an antenna cover that houses the first and second directional antenna portions is provided, and the antenna cover is a rectangular tube on the mounting portion side. It is formed in a taper shape so as to become thinner as it goes in the tip direction, and has a streamline shape in both the front and rear directions.

The fourth invention is, in the two-way beam antenna according to the third invention, the husband of the first and second directional antenna unit s, the patch antenna of each side length of substantially 1/4 wavelength Each of the parasitic elements of the multistage parasitic element is formed in a substantially rectangular shape in which the length of each side is sequentially reduced as the distance from the patch antenna increases, and a ground plate, the patch antenna, and each parasitic element are formed. Vertically polarized wave having a patch antenna and a rod-shaped antenna arm that passes through the support hole in the center of the feed element and holds each parasitic element at a predetermined interval with the direction of the sides aligned and fixed to the ground plate It is characterized by being an antenna.

A fifth invention, in bidirectional beam antenna according to the fourth invention, the back of the mounting portion, for fixing the mounting braces in a plurality of different positions on both sides direction, a plurality of stepped recesses and U In the state where the bolt insertion hole is provided and the mounting portion cover made of metal having a substantially U-shaped cross section covering the upper and lower surfaces and the front surface of the mounting portion is detachably provided on the mounting portion, and the mounting portion cover is removed. A U-bolt can be attached to and detached from the rear surface of the mounting portion .

A sixth aspect of the present invention is the bidirectional beam antenna according to the first aspect , wherein the bidirectional beam antenna is provided at a tip of each of the two patch antennas provided on a cylindrical unidirectional side. Two multi-stage parasitic elements that are gradually reduced in size toward the ground plate, and are attached to the ground plate. The patch antenna and the multi-stage parasitic elements are accommodated, and the mounting portion side is a rectangular tube that becomes thinner toward the tip. Two antenna covers formed so as to be tapered, and the direction in which the cylindrical unidirectionality is formed is the longitudinal direction of the bidirectional beam antenna .

A transmission system according to a seventh aspect of the present invention is that a plurality of bidirectional beam antennas according to any of the first to third aspects of the invention are arranged at intervals in the upper, lower, left and right sides, and transmitted by a spatial diversity method. Features.

  According to the first invention, a high gain directional antenna is formed by the patch antenna and the multistage parasitic elements and the distributor is built in, so that assembly and adjustment at the site becomes unnecessary, and the product cost and construction cost are reduced. As a result, the electrical characteristics can be stabilized, and the side lobe can be further reduced.

  According to the second invention, a patch antenna having a unidirectionality having a radiation element composed of a radiation plate and a ground plate in communication between a train operating on a track or a vehicle traveling on a main road and a railway line. Directivity in the longitudinal direction along the track or road route by using two-way beam antennas that are arranged with their backs facing each other and that prevent mutual interference of radio waves in each patch antenna by the ground plate Can be specialized. In addition, since the antenna has a patch shape, the directivity spreads substantially uniformly in the vertical and horizontal ranges in the longitudinal direction, and the null point is reduced. That is, it is possible to construct a communication system having a high gain in the direction, high transmission quality, and excellent cost effectiveness. In addition, by configuring the radiating element with a radiating plate and a ground plate, the ground plate has a shielding function, and interference of radio waves to the rear can be greatly reduced. Further, it is possible to further reduce the mutual interference of radio waves by increasing the size of the ground plate.

  According to the third invention, the patch antenna is composed of the waveguide element and the radiating element, and each element is three-dimensionally arranged, so that the unidirectionality is increased, and on the track or on the road Directivity narrowed down by the periphery can be obtained.

  According to the fourth invention, by using two or more waveguide elements of the patch antenna, directivity and gain can be increased, and the features of the present invention can be further extracted.

  According to the fifth aspect, by using the two distributors, the number of feeder lines can be reduced to one and the entire configuration can be simplified. Further, by accommodating two patch antennas and two distributors in one housing, the compactness can be increased, and the bidirectional beam antenna according to the present invention can be easily installed on the top of a utility pole, a train or an automobile. In particular, in the case of trains, the space where antennas can be installed is limited due to building limits and vehicle limits due to the relationship with tunnels and overhead lines, but the present invention can be installed in such limited spaces.

  According to the sixth invention, the casing in the fifth invention has a streamlined shape in the front-rear direction, so that the wind pressure is minimized during high-speed operation, for example, when installed in the upper part of a train. Can be fastened. The streamlined shape is made possible based on the fact that the size of the antenna element is gradually reduced toward the tip.

  According to the seventh invention, by arranging a plurality of bidirectional beam antennas according to the present invention, the effect of the space diversity system can be obtained, and the transmission quality can be further improved. By storing the bidirectional beam antenna in the housing, the configuration is extremely simple, and a plurality of antennas can be installed in a narrow space.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
The first embodiment shows an example in which the present invention is applied to a bidirectional beam antenna for a 2.4 GHz band wireless LAN used for a fixed station, for example. FIG. 1 is a perspective view showing a state where a fixed-station bidirectional beam antenna 20 according to a first embodiment of the present invention is attached to an attachment column 19.

  The bidirectional beam antenna 20 includes an attachment portion 21 and antenna portions 22a and 22b provided on the left and right sides of the attachment portion 21. The attachment portion 21 is provided with a metal attachment portion cover 23 having a substantially U-shaped cross-section so as to cover the upper and lower surfaces and the front surface, by a plurality of screws, for example, four upper and lower screws 24. In addition, two U bolts 25 for mounting on the mounting column 19 are provided on the back surface of the mounting portion 21 at a predetermined interval in the vertical direction. The U bolt 25 can be attached to and detached from the attachment portion 21 with the attachment portion cover 23 removed. When the bidirectional beam antenna 20 is attached to the attachment column 19, the bidirectional beam antenna 20 is fixed to the attachment column 19 with the U bolt 25 with the attachment portion cover 23 removed from the attachment portion 21, and then the attachment portion 21. Attach the attachment cover 23 to the.

  As will be described in detail later, the antenna portions 22a and 22b constitute a high gain directional antenna by a patch antenna and multistage parasitic elements, and have directivity in the left and right directions as indicated by arrows. . The antenna portions 22a and 22b protect the periphery of the antenna with an antenna cover 26 made of synthetic resin. The antenna cover 26 is formed in a rectangular tube shape on the mounting portion 21 side, but is formed in a cylindrical shape on the tip end side, and has a taper shape, that is, a streamline shape so as to become thinner toward the tip end direction. Is formed. Further, a drain hole (not shown) is provided on the lower surface of the antenna cover 26. The antennas constituting the antenna portions 22a and 22b are fed with power through a two distributor provided in the mounting portion 21. A coaxial cable for power feeding 27 is connected to the two distributors, and a plug 28 is attached to the tip thereof.

  The bi-directional beam antenna 20 is attached to mounting posts 19 provided at a predetermined interval, for example, several hundred meters, for example, along a railroad track. Wireless communication is performed for a 4 GHz band wireless LAN. For example, IEEE802.11b is used as a wireless communication standard.

Next, a detailed configuration inside the bidirectional beam antenna 20 will be described.
2A is a top view showing a part of the attachment part cover 23 of the bidirectional beam antenna 20 cut away, and FIG. 2B is a front view showing part of the attachment part cover 23 and other parts cut away. The figure and the figure (c) are the side views.

  As shown in FIG. 2A, the mounting portion 21 is provided with a first antenna mounting bracket 31 on the back side and a second antenna mounting bracket 32 on the front side. The first antenna mounting bracket 31 is configured as shown in FIG. 3A is a top view of the first antenna mounting bracket 31, FIG. 3B is a front view thereof, and FIG. 3C is a side view thereof. The first antenna mounting bracket 31 includes a bracket main body portion 33 made of a rectangular metal plate and bent portions 33a to 33d that are bent in a predetermined direction on the top and bottom and left and right in the back direction. The upper and lower bent portions 33a and 33b are provided with concave portions 34a to 34c for attachment to the attachment column 19 at the center and on the left and right sides thereof. Each of the recesses 34 a to 34 c is formed in a step shape with a width of several millimeters so that the recess 34 a to 34 c is securely fixed to the mounting column 19. The bent portions 33a and 33b are provided with screw holes 38 for fixing the attachment portion cover 23, respectively. The second antenna mounting bracket 32 is also provided with a screw hole 38 for fixing the mounting portion cover 23 to the upper and lower bent portions as shown in FIG.

  Further, as shown in FIG. 3B, the metal fitting main body portion 33 has four bolt holes 35 for inserting the U bolts 25 so as to be positioned on both sides of the concave portions 34a to 34c on the upper side and the lower side. Provided. Normally, the U bolts 25 are inserted into the bolt holes 35 located on both sides of the central recess 34b, but the U bolts 25 can be selectively mounted on the left and right recesses 34a and 34c. . That is, the concave portions 34 a to 34 c are arbitrarily selected according to the installation conditions of the bidirectional beam antenna 20, and the mounting bolt 19 can be attached by attaching the U bolt 25. As shown in FIG. 2, a nut 36 is screwed to the tip of the U bolt 25 inserted into the bolt hole 35. The nut 36 is fixed to the mounting column 19 by the recessed portions 34 a to 34 c and the U bolt 25 selected by tightening the nut 36.

  Further, the left and right bent portions 33c and 33d of the first antenna mounting bracket 31 are provided with base mounting holes 37 in the upper and lower portions as shown in FIG. Also, base mounting holes (not shown) are provided on both sides of the second antenna mounting bracket 32 shown in FIG. A base plate 51 for mounting an antenna shown in FIG. 4 is mounted on both sides of the first antenna mounting bracket 31 and the second antenna mounting bracket 32 by screws 52 using the base mounting holes 37. The base plate 51 is provided with a hole 50 for inserting a screw 52. The base plate 51 is made of a metal plate, has a function as a ground plate and a reflection plate of the antenna portion 22a (22b), and is used as an antenna mounting substrate.

  Further, the first antenna mounting bracket 31 is provided with four screw holes 41 for mounting the two distributors in the bracket main body 33, and these screw holes 41 are used for FIG. As shown in b), a two-distributor 42 is attached at a position above the center. In FIG. 2B, a part of the attachment cover 23 is notched and the second antenna attachment bracket 32 is omitted.

Similar to the first antenna mounting bracket 31, the second antenna mounting bracket 32 is constructed by bending the upper and lower sides and the left and right sides of the bracket body portion in the front direction, and a detailed description thereof will be omitted.
The two distributors 42 attached to the first antenna mounting bracket 31 are provided with a substrate 44 in a case 43, and two distribution lines are formed on the substrate 44 by a microstrip line. Further, one end portions of the rigid cables 45a and 45b are fixed to the board 44 by rigid cable pressing metal fittings 46a and 46b on both sides of the lower part on the front side. The rigid cables 45 a and 45 b are soldered to the distribution terminals of the two distribution lines formed on the substrate 44 at the end portions of the center conductor. The other ends of the rigid cables 45a and 45b are fixed to an antenna mounting base plate 51, as will be described in detail later, and the tip of the central conductor is soldered to an antenna element, that is, a feeding point of a patch antenna.

  Further, on the substrate 44 of the 2-distributor 42, one end portion of the feeding coaxial cable 27 is fixed to the lower center of the front surface side by a cable pressing metal 47, and the distal end portion of the central conductor is formed on the substrate 44. Soldered to the power supply terminal of the line. A ring-shaped buffer member 48 previously formed of rubber is fitted into the power supply coaxial cable 27, and a groove provided on the outer peripheral edge of the buffer member 48 as shown in FIG. It fits in a U-shaped groove formed in the cover 23. The plug 28 is attached to the other end of the power supply coaxial cable 27 as described above.

  Next, the configuration of the antenna units 22a and 22b will be described. 4A is a view of the antenna portions 22a and 22b as viewed from the side of the base plate 51 for mounting the antenna, and FIG. 4B is a side view in which the antenna cover 26 in the antenna portions 22a and 22b is partially cut away. is there.

  The base plate 51 is provided with an antenna support hole in the center thereof, and for example, an antenna arm 53 is inserted into the hole from the outside toward the antenna cover 26. The antenna arm 53 uses, for example, a metal screw rod, and has a screw head formed at one end and a screw portion formed at the other end. A base plate 51, a patch antenna 54, and a plurality of stages, for example, four stages of parasitic elements 55a to 55d are attached to the antenna arm 53 at predetermined intervals. The interval between the base plate 51 and the patch antenna 54 is set to approximately λ / 20 (λ: wavelength of the used frequency). The interval between the parasitic elements 55 a to 55 d is basically set to approximately λ / 4, but is set to gradually increase as the distance from the patch antenna 54 increases. As described above, a high gain directional antenna is configured by combining the patch antenna 54 and the multistage parasitic elements 55a to 55d functioning as waveguide elements.

  The antenna arm 53 holds spacers 56a to 56e between the base plate 51 and the patch antenna 54, and between the patch antenna 54 and the parasitic elements 55a to 55d, respectively, so that the elements are held at a predetermined interval. Then, a nut 57 is screwed onto the screw portion at the tip, and the antenna portion is fixed to the base plate 51 for mounting the antenna. Further, for example, a vibration isolating member 61 is interposed in the antenna arm 53 as a cushioning material between the parasitic elements 55b and 55c. As will be described in detail later, the vibration isolation member 61 is made of an elastic material such as sponge, and holds the antenna arm 53 on the central axis of the antenna cover 26 by bringing the outer peripheral edge into contact with the inner side of the antenna cover 26.

  The antenna cover 26 is provided with screw holes at a plurality of, for example, six locations on the periphery of the opening. Screws 58 are screwed into the screw holes from the outside of the base plate 51, and the antenna cover 26 is attached to the base plate 51. Fix it.

  As shown in FIG. 5A, the patch antenna 54 is formed, for example, in a substantially square shape, and transmits and receives a vertically polarized signal. The patch antenna 54 has a thickness of about 1 mm and a side length of about λ / 4, and is provided with a support hole 62 for inserting the antenna arm 53 at the center. Further, the patch antenna 54 is provided with a feeding point 63 with a distance d1 downward from the support hole 62, and with a direction alignment hole 64 with a distance d2 from the central support hole 62 in the direction of the right side, for example. Is provided. The feeding point 63 is provided with a hole that is large enough to insert the central conductor of the rigid cables 45a and 45b. The direction alignment hole 64 is for aligning the direction of the patch antenna 54 and the parasitic elements 55a to 55d with a certain direction.

  The parasitic elements 55a to 55d are formed in a substantially square shape like the patch antenna 54 as shown in FIG. The parasitic elements 55 a to 55 d are formed, for example, with a thickness of about 1 mm and a length of each side slightly shorter than the patch antenna 54. In this case, the parasitic elements 55a to 55d are formed such that the lengths of the respective sides are sequentially shortened as the distance from the patch antenna 54 increases. However, the parasitic elements 55c and 55d in the distal direction may have the same dimensions. In addition, the parasitic elements 55a to 55d are provided with a support hole 65 for inserting the antenna arm 53 at the center, and a direction adjusting hole 66 is provided from the support hole 65 in the direction of the right side while maintaining a distance d2. . The direction adjusting holes 66 of the parasitic elements 55 a to 55 d are provided at the same positions as the direction adjusting holes 64 of the patch antenna 54.

  Also in the base plate 51, as shown in FIG. 4A, a direction adjusting hole 67 is provided at a position corresponding to the support hole 65 of the patch antenna 54 and the direction adjusting hole 66 of the parasitic elements 55a to 55d. .

  When the patch antenna 54 and the parasitic elements 55a to 55d are attached to the base plate 51 via the antenna arm 53, the direction adjusting rod 68 is inserted from the direction adjusting hole 67 provided in the base plate 51 as shown in FIG. Furthermore, the patch antenna 54 and the parasitic elements 55a to 55d are inserted into the alignment holes 64 and the parasitic elements 55a to 55d so that the directions of the patch antenna 54 and the parasitic elements 55a to 55d are aligned. In this state, the nut 57 is fastened to the antenna arm 53 to fix the antenna arm 53 to the base plate 51. Thereafter, the direction adjusting rod 68 is taken out.

  Further, a rigid cable mounting bracket 59 is attached to the base plate 51 at a position corresponding to the feeding point 63 of the patch antenna 54 as shown in FIG. The rigid cable mounting bracket 59 is provided with a hole for inserting the rigid cables 45a and 45b in the center. The rigid cables 45a and 45b are inserted at their tips into holes in the rigid cable mounting bracket 59, and the outer conduit is fixed by soldering. The leading ends of the central conductors of the rigid cables 45a and 45b are inserted in a state where the base plate 51 is insulated from the rigid cable mounting bracket 59, pass through the hole of the feeding point 63 provided in the patch antenna 54, and the leading ends thereof are It is bent and soldered.

  As described above, the antenna portions 22a and 22b in which the antenna arm 53 and the antenna element 53 are attached to the base plate 51 have base attachment holes 37 provided on the left and right of the first antenna attachment bracket 31 and the second antenna attachment bracket 32, respectively. The base plate 51 is attached and fixed by screws 52.

  Further, the vibration isolating member 61 attached to the antenna arm 53 is configured as shown in FIGS. FIG. 7A is a side view of the vibration isolation member 61, and FIG. 7B is a front view. The anti-vibration member 61 is configured by adhering a first anti-vibration material 61a having a thickness t1 and a second anti-vibration material 61b having a thickness t2 formed of an elastic material such as sponge to an adhesive. The thickness t2 of the second anti-vibration material 61b is formed, for example, about 1.5 times thicker than the thickness t1 of the first anti-vibration material 61a. In this case, the total thickness (t1 + t2) of the first vibration isolation material 61a and the second vibration isolation material 61b is set according to the interval between the parasitic elements 55c and 55d. The first anti-vibration material 61a and the second anti-vibration material 61b are sponges having different hardness, for example, the first anti-vibration material 61a has a hardness of about 30 degrees and the second anti-vibration material 61b has a hardness of about 40 degrees. A sponge is used. The first vibration isolator 61a is formed in, for example, an octagon so that the outer peripheral surface is in contact with the inside of the antenna cover 26, and the second vibration isolator 61b is formed in a quadrilateral smaller than the first vibration isolator 61a.

  The first anti-vibration material 61a and the second anti-vibration material 61b are bonded so that the four sides are located correspondingly, and a slit 61c is formed from one side to the center. The height of the slit 61c is set to be smaller than the diameter of the spacers 56a to 56e. Further, the slit 61c is provided such that the bottom is deeper than the center by a distance t3. This distance t3 is set to about ½ of the height of the slit 61c. That is, when the vibration isolation member 61 is attached to the antenna arm 53, the antenna arm 53 and the spacer 56d are positioned at the center of the vibration isolation member 61.

  The anti-vibration member 61 configured as described above has the second anti-vibration member 61b in contact with the non-feed element 55c and the first anti-vibration member 61a between the non-feed elements 55c and 55d. It is attached to the antenna arm 53 so as to contact. In the antenna arm 53, a spacer 56d is interposed in a portion where the vibration isolation member 61 is attached.

  Then, after attaching the vibration isolating member 61 to the antenna arm 53, the antenna cover 26 covering the antenna portions 22a and 22b is attached. That is, the screws 58 are screwed from the outside of the base plate 51 to the screw holes at six positions provided on the periphery of the opening of the antenna cover 26, and the antenna cover 26 is fixed to the base plate 51. At this time, the vibration isolation member 61 holds the antenna arm 53 at the center of the antenna cover 26 with the outer peripheral surface of the first vibration isolation member 61 a contacting the inside of the antenna cover 26. The anti-vibration member 61 is configured by combining the first anti-vibration material 61a having a low hardness and the second anti-vibration material 61b having a high hardness, so that the vibration from the antenna cover 26 can be reliably absorbed, and The antenna arm 53 can be reliably held.

  In the bidirectional beam antenna 20 shown in the first embodiment, when the frequency is set to 2.4 GHz and the impedance is set to 50Ω, the vertical polarization horizontal plane directivity shown in FIG. 8 and the vertical polarization vertical plane directivity shown in FIG. Sex was obtained. In the bidirectional beam antenna 20 according to the first embodiment, the absolute gain was 7 dBi or more and the standing wave ratio was 1.7 or less.

  According to the first embodiment, the base plate 51, the patch antenna 54, and the multistage parasitic elements 55a to 55d constitute the antenna portions 22a and 22b and the two distributors 42 are built in. No adjustment is required, and the product cost and construction cost can be reduced. Further, since the connection between the two distributors 42 and the antenna portions 22a and 22b is made by internal wiring without using a connector, the electrical characteristics can be stabilized. Further, by combining the base plate 51 having the function of a ground plate (reflecting plate), the patch antenna 54 and the multistage parasitic elements 55a to 55d to form the high-gain directional antenna portions 22a and 22b, As shown in the radiation characteristics of FIG. 8, a further reduction in side lobe could be realized.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.
The second embodiment shows an example in which the present invention is applied to, for example, a bidirectional beam antenna for 2.4 GHz band wireless LAN used for a mobile station, for example. This bidirectional beam antenna for a mobile station is used by being mounted on, for example, a roof of a train.

  10A and 10B show a state in which the fixed-station bidirectional beam antenna 20A according to the second embodiment of the present invention is attached to the vehicle body roof 72 by the mounting bracket 71. FIG. 10A is a rear view, and FIG. A bottom view and (c) are side views. In addition, the same code | symbol is attached | subjected to the same part as the bidirectional beam antenna 20 which concerns on the said 1st Embodiment, and detailed description is abbreviate | omitted.

  In the bidirectional beam antenna 20 </ b> A according to the second embodiment, a bottom plate 73 is provided on the bottom surface of the attachment portion 21, and an attachment fitting 71 is attached to the bottom plate 73 and attached to the vehicle roof 72. As will be described later in detail, a plurality of, for example, five fixing nuts 74 are provided on the bottom plate 73, and the mounting bracket 71 is fixed by bolts 75 using the fixing nuts 74. Then, the mounting bracket 71 is fixed to the vehicle roof 72 with bolts 76.

  The attachment portion cover 23a of the attachment portion 21 is made of a synthetic resin such as FRP (Fiberglass Reinforced Plastic) and has a plate thickness of about 8 mm and a substantially U-shape. The lower surface of the upper surface, the front surface, and the rear surface are fixed to the internal mounting bracket by a plurality of screws 24. Further, as shown in FIG. 10A, a groove 77 for inserting the power feeding coaxial cable 27 is formed in the center of the lower portion of the back surface in the attachment portion cover 23a.

  11A and 11B show the internal structure of the bidirectional beam antenna 20A. FIG. 11A is a top view showing a part of the mounting portion cover 23a, and FIG. A sectional view taken along line A, (c) is a sectional view taken along line BB in FIG.

  As shown in FIG. 11A, the mounting portion 21 is provided with a first antenna mounting bracket 31 on the back side and a second antenna mounting bracket 32 on the front side. The first antenna mounting bracket 31 in the second embodiment is not provided with the U-bolt mounting recesses 34a to 34c (see FIG. 3A) shown in the first embodiment.

The first antenna mounting bracket 31 and the second antenna mounting bracket 32 have base plates 51 mounted on both sides in the same manner as in the first embodiment, and the antenna portions 22a and 22b are mounted on the base plate 51. Is done.
The first antenna mounting bracket 31 is provided with a two distributor 42 on the front side. In the two distributors 42, one ends of rigid cables 45a and 45b are fixed to the upper both sides on the front side of the substrate 44 by rigid cable holding fittings 46a and 46b. The rigid cables 45 a and 45 b are soldered to the distribution terminals of the two distribution lines 49 formed on the substrate 44 at the end portions of the center conductor. The other ends of the rigid cables 45 a and 45 b are fixed to the antenna mounting base plate 51, and the tip of the central conductor is soldered to the feeding point of the patch antenna 54.

  On the back side of the substrate 44 of the 2-distributor 42, a feeding coaxial cable 27 is attached by a connector 78, and the central conductor thereof is soldered to the feeding point of the two distribution lines 49 through a through hole.

  A bottom plate 73 shown in FIG. 12 is fixed to the lower side of the first antenna mounting bracket 31 and the second antenna mounting bracket 32 with a nut using a fixing bolt 84 as will be described later. FIG. 12 shows a detailed configuration of the bottom plate 73, where (a) is a top view, (b) is a top side view, (c) is a bottom side view, and (d) is a right side view. The bottom plate 73 includes a bottom plate main body portion 81 made of a rectangular metal plate and bent portions 81a to 81d obtained by bending the upper and lower and left and right predetermined widths in the back direction. The upper and lower bent portions 81a and 81b are provided with a plurality of screw holes 82 for fixing the attachment portion cover 23a. For example, two screw holes 82 are provided in the upper bent portion 81a, and four screw holes 82 are provided in the lower bent portion 81b.

  The bottom plate body 81 is provided with the fixing nut 74 described above at a position displaced by a predetermined distance, for example, near the four corners and above the center toward the bent portion 81a. The fixing nut 74 has a thread groove formed on the inner peripheral surface of the cylindrical member, and is used for fixing the mounting bracket 71 with a bolt 75 (see FIG. 10). The bottom plate body 81 is provided with the fixing bolt 84 on the inner side of the fixing nuts 74 near the four corners. The fixing bolt 84 has a threaded portion formed on the outer periphery of the cylindrical member, and is for fixing the bottom plate 73 to the first antenna mounting bracket 31 and the second antenna mounting bracket 32. As shown in FIGS. 11A and 11C, the bottom plate 73 is fixed to the first antenna mounting bracket 31 and the second antenna mounting bracket 32 by screwing a nut 85 to the fixing bolt 84 as shown in FIGS. . Further, the bottom plate 73 is provided with air holes 86 at four corners.

  Since the configuration of the antenna units 22a and 22b in the bidirectional beam antenna 20A is the same as that of the bidirectional beam antenna 20 shown in the first embodiment, detailed description thereof is omitted.

  The bidirectional beam antenna 20A configured as described above is used with the mounting bracket 71 attached to the bottom plate 73 with the bolt 75 and the vehicle roof 72 attached with the bolt 76 as described in FIG. The

  The bidirectional beam antenna 20A according to the second embodiment can be reliably mounted on a vehicle roof 72 such as a train using a mounting bracket 71 shown in FIG. 10, for example, and can be used for a mobile station. it can. The bidirectional beam antenna 20A has the same radiation characteristics as the bidirectional beam antenna 20 shown in the first embodiment, that is, the vertical polarization horizontal plane directivity shown in FIG. 8 and the vertical polarization vertical plane shown in FIG. Directivity can be obtained.

  In the bidirectional beam antenna 20A shown in the second embodiment, as in the bidirectional beam antenna 20 according to the first embodiment, on-site assembly and adjustment are unnecessary, and electrical characteristics are stabilized and costs are reduced. And further lower side lobes can be realized.

(Third embodiment)
Next, a third embodiment of the present invention will be described.
FIG. 13 is a plan view of a bidirectional beam antenna according to a third embodiment of the present invention. The bidirectional beam antenna has two left and right patch antennas, and each patch antenna has waveguide elements (parasitic elements) 91, 92, 93, 94 and a radiating element 97 as antenna elements. The radiating element 97 includes a radiating plate 95 and a ground plate 96. Each element is connected by a connecting rod 99. A feed line 98 connected to the transceiver is connected to the radiation plates 95 of the left and right patch antennas.

  FIG. 14 is a plan view of the case where the bidirectional beam antenna shown in FIG. In this case, the power supply line 98 is connected to the transmitter / receiver by the two distributor 100. The casing 101 that houses the bidirectional beam antenna is formed of, for example, a metal material at the center and ABS resin on both sides, and has an overall length of approximately 600 mm and a diameter of the center of approximately 150 mm. The specific structure of the bidirectional beam antenna according to the third embodiment is the same as that of the first embodiment or the second embodiment.

  The operation of the bidirectional beam antenna will be described with reference to FIG. In the case of transmission, radio waves radiated from the radiation plate 95 through a feeder line 98 from a transceiver (not shown) are transmitted to the left side of the drawing by the waveguide elements 94, 93, 92, 91. Since the shape of the radiating element is a plane, the antenna has a uniform cylindrical directivity in the upper and lower sides and the left and right sides, and can be reliably transmitted even in a running train.

  At this time, the ground plate 96 shields the transmission of radio waves and prevents radio wave interference with the patch antenna on the right side of the drawing. Therefore, the left and right antennas can be installed on the same axis and close to each other.

  At the time of reception, the radio wave is strengthened by the waveguide elements 91, 92, 93, 94 and received by the radiation plate 95. The radio wave that could not be received by the radiation plate 95 is reflected by the ground plate 96 to prevent interference with the patch antenna on the right side of the drawing as in the case of transmission.

  As described above, it is possible to construct a wireless LAN with high transmission quality between a traveling train that requires a long service area in the longitudinal direction and points on the track side.

  Next, a case where the antenna is stored in the housing 101 will be described with reference to FIG. Since only one power supply line 98 is required by installing the two distributors 100, the connection between the casing 101 and the transmitter / receiver is simplified. The function of the antenna in transmission and reception is the same as described above, has high directivity on the left and right sides, and can reduce the mutual interference of radio waves between the left and right antennas.

  The measured values of the directivity of the bidirectional beam antenna according to the above embodiment are shown in FIGS. FIG. 15 shows vertical polarization horizontal plane directivity, and FIG. 16 shows vertical polarization vertical plane directivity. The measurement was performed in an anechoic chamber, and the antenna was fixed at a height of 1.5 m and placed on a turntable. The transmitting antenna was a standard antenna (electromagnetic horn antenna) installed at a height of 1.5 m and a distance of 5 m. Radio waves were emitted from the transmitting antenna, the turntable of this antenna was rotated, and the received power was measured. As a result, as shown in FIG. 15 and FIG. 16, a substantially uniform directivity in the vertical and horizontal directions could be obtained.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described.
FIG. 17 shows a case where the bidirectional beam antenna according to the third embodiment is housed in a casing and installed on a telephone pole beside a railroad track. 111 and 112 are bidirectional beam antennas according to the above embodiment, 113 is a utility pole, and 114 is a fastener for fixing the two bidirectional beam antennas 111 and 112 to the utility pole 113.

  The housing for storing the bidirectional beam antennas 111 and 112 is formed of, for example, a metal material at the center and ABS resin on both sides, and has an overall length of approximately 600 mm and a diameter of the center of approximately 150 mm. The two-way beam antennas 111 and 112 are installed in two upper and lower stages using a stopper 114 on a power pole 113 at the time of a track, and adopt a space diversity system. It is sufficient that the distance between the two-way beam antennas 111 and 112 is about 500 mm or more. Reference numeral 115 denotes a wireless LAN bridge, and reference numerals 116 and 117 denote power supply lines that connect the wireless LAN bridge 115 and the bidirectional beam antennas 111 and 112, respectively.

  The functions of the bidirectional beam antennas 111 and 112 are the same as those in the above embodiment. The bi-directional beam antennas 111 and 112 have the same directivity on the left and right lines of the drawing, and adopt a spatial diversity system to maintain high-quality transmission and to the left and right longitudinal directions. A very long service area can be configured. Moreover, since it is stored in the housing, it can withstand wind and rain and flying objects without problems.

(Fifth embodiment)
Next, a fifth embodiment of the present invention will be described.
FIG. 18 shows a case where the bidirectional beam antenna according to the second embodiment or the third embodiment is mounted on the top of the first vehicle or the last vehicle of the train 120. The train 120 has shown the state currently operating on the track | truck 123 to the right direction. Reference numerals 121 and 122 denote bidirectional beam antennas according to the present invention, which employ a space diversity system. The internal structure of the bidirectional beam antennas 121 and 122 is the same as in the second and third embodiments. The casings of the bidirectional beam antennas 121 and 122 are, for example, formed by FRP material at the center and ABS resin at both sides, and the entire length and the diameter of the center are the same as those installed on the utility pole. The reason why the central part of the housing is made of FRP material is to ensure insulation in case of cutting the overhead wire. It is sufficient that the distance between the bidirectional beam antennas 121 and 122 is about 500 mm as in the case of the utility pole.

  The bi-directional beam antennas 121 and 122 are equally directional in the same direction along the line 123 on the left and right of the drawing, and maintain high quality transmission characteristics by adopting a spatial diversity system. In addition, a service area that is long in the longitudinal direction can be configured.

  Since the casings of the bidirectional beam antennas 121 and 122 have a streamlined shape at the front and rear, the air resistance can be minimized even when the train 120 operates at a high speed. In addition, the central part of the housing is made of FRP material, both sides are made of ABS resin, and the inside of the antenna parts on both sides is packed with cushioning material (vibration-proofing members) to protect the antenna elements. The antenna can be protected from flying objects without being affected.

  FIG. 19 shows an example in which the bidirectional beam antennas 121 and 122 according to the present invention are installed above the track 131 and the space diversity system is adopted. The track 131 shows a state of traveling in the right direction in the drawing.

  When the bi-directional beam antennas 121 and 122 are installed on the upper part of the track 131, the high-quality transmission is maintained and the length along the road is maintained by adopting the spatial diversity method as in the case of installing the upper part of the train 120. A long service area can be constructed in the direction.

  The present invention is extremely useful as a communication means between a train or a car and a railway line. That is, by installing the bidirectional beam antenna according to the present invention on the point near the track or on the main road, on the train to be operated or on the traveling vehicle, it is long and high in gain between the transmission / reception point on the ground and the train / vehicle. A service area can be constructed.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

It is a perspective view which shows the state which attached the bidirectional beam antenna for fixed stations which concerns on 1st Embodiment of this invention to the attachment support | pillar. It is a figure which shows the detail inside the bidirectional | two-way beam antenna in the embodiment, (a) is a top view which notches and shows a part of attachment part cover, (b) shows a part of attachment part cover, and another part. The front view shown notched and (c) are side views. It is a figure which shows the detail of the 1st antenna attachment metal fitting in the embodiment, (a) is a top view, (b) is a front view, (c) is a side view. The details of the antenna part in the same embodiment are shown, (a) is a view of the antenna part from the side of the base plate for mounting the antenna, (b) is a side view showing a part of the antenna cover. (A) is a front view which shows the detail of the patch antenna in the embodiment, (b) is a front view which shows the detail of the parasitic element in the embodiment. It is explanatory drawing in the case of matching the direction of the patch antenna and parasitic element in the embodiment. (A) is a side view of the vibration isolator in the same embodiment, (b) is the front view. It is a figure which shows the vertical polarization horizontal plane directivity of the bidirectional | two-way beam antenna in the same embodiment. It is a figure which shows the vertical polarization vertical surface directivity of the bidirectional | two-way beam antenna in the same embodiment. The state which attached the bidirectional | two-way beam antenna for fixed stations which concerns on 2nd Embodiment of this invention to the vehicle body roof with a mounting bracket is shown, (a) is a rear view, (b) is a bottom view, (c). Is a side view. The internal structure of the bidirectional beam antenna in the embodiment is shown, (a) is a top view showing a part of the mounting portion cover, and (b) is an AA line arrow in FIG. (C) is a cross-sectional view taken along the line BB in FIG. The detailed structure of the baseplate in the embodiment is shown, (a) is a top view, (b) is an upper side view, (c) is a lower side view, and (d) is a right side view. It is a top view of the bidirectional beam antenna which concerns on 3rd Embodiment of this invention. It is a top view which shows the state which stored the bidirectional | two-way beam antenna in the same embodiment in the housing | casing. It is a figure which shows the vertical polarization horizontal plane directivity of the bidirectional | two-way beam antenna in the same embodiment. It is a figure which shows the vertical polarization vertical surface directivity of the bidirectional | two-way beam antenna in the same embodiment. It is a front view which shows the example which installed the bidirectional beam antenna which concerns on 4th Embodiment of this invention in the utility pole. It is a figure which shows the example which installed the bidirectional beam antenna which concerns on 5th Embodiment of this invention in the train upper part. It is a figure which shows the example which installed the bidirectional beam antenna in the embodiment in the upper part of a track. It is a figure which shows the structural example of the conventional bidirectional beam antenna. It is a figure which shows the vertical polarization horizontal plane directivity of the conventional bidirectional beam antenna.

Explanation of symbols

  20, 20A ... Bidirectional beam antenna, 21 ... Mounting portion, 22a, 22b ... Antenna portion, 23, 23a ... Mounting portion cover, 24 ... Screw, 25 ... U bolt, 26 ... Antenna cover, 27 ... Coaxial cable for feeding, 28 ... Connector, 31 ... First antenna mounting bracket, 32 ... Second antenna mounting bracket, 33 ... Bass main body, 33a to 33d ... Bent portion, 34a to 34c ... Recess, 35 ... Bolt hole, 36 ... Nuts 37 ... Base mounting holes 38, 41 ... Screw holes, 42 ... Two distributors, 43 ... Cases, 44 ... Substrate, 45a, 45b ... Rigid cables, 46a, 46b ... Rigid cable retainers, 47 ... Cable retainers 48 ... Buffer member, 49 ... Distribution line, 50 ... Hole, 51 ... Base plate, 52 ... Screw, 53 ... Antenna arm, 54 ... Patch antenna, 55a-55d ... No power supply Child 56a-56e Spacer 57 Nut 58 Screw 59 Rigid cable mounting bracket 61 Vibration isolation member 61a First vibration isolation 61b Second vibration isolation 61c Slit 62 ... support hole, 63 ... feeding point, 64, 66, 67 ... direction alignment hole, 65 ... support hole, 68 ... direction alignment rod, 71 ... mounting bracket, 72 ... body roof, 73 ... bottom plate, 74 ... fixing nut, 75 , 76 ... Bolt, 77 ... Groove, 78 ... Connector, 81 ... Bottom plate main body part, 81a to 81d ... Bent part, 82 ... Screw hole, 84 ... Fixing bolt, 85 ... Nut, 86 ... Air hole, 91, 92, 93, 94: Waveguide element, 95: Radiation plate, 96: Earth plate, 97 ... Radiation element, 98 ... Feeding line, 99 ... Connecting rod, 100 ... Distributor, 101 ... Housing, 111, 112 ... Bidirectional beam Antenna, 113 ... electric pole, 114 ... Ingredients, 115 ... LAN bridge, 116, 117 ... feeders, 120 ... train, 121.122 ... bidirectional beam antenna, 123 ... line, 131 ... track.

Claims (7)

A first portion formed by combining a mounting portion having a mounting mechanism for mounting on another support member, a patch antenna provided on both sides of the mounting portion, and a multistage parasitic element that gradually decreases in size toward the tip . A bidirectional beam antenna comprising: a second directional antenna unit; and a distributor that is provided in the attachment unit and feeds power to the first and second directional antenna units. In communication between trains and cars along the line,
Radiating plate and disposed in back to back with each other patch antenna 2 group coaxially with unidirectional having a radiating element comprising a ground plate, anti skill radio mutual interference in each patch antenna by said ground plate The bidirectional beam antenna is characterized in that the same cylindrical directivity is formed before and after the apparatus . An antenna cover for accommodating the first and second directional antenna portions is provided, and the antenna cover is formed in a rectangular tube shape on the mounting portion side and is tapered so as to become thinner toward the distal end. 2. The bidirectional beam antenna according to claim 1 , wherein the bidirectional beam antenna has a streamline shape toward both directions. Each of the first and second directional antenna sections includes the patch antenna formed in a substantially quadrangular shape with each side having a length of approximately ¼ wavelength, and each parasitic element of the multistage parasitic element is connected to the patch. Each of the sides is formed in a substantially rectangular shape whose length is gradually reduced as it is away from the antenna, and further passes through a grounding plate, a central support hole of the patch antenna and the parasitic elements, and the patch antenna and the parasitic elements. The bidirectional beam antenna according to claim 3, wherein the antenna is a vertically polarized antenna having a rod-shaped antenna arm that is fixed to the ground plate while being held at a predetermined interval with the directions of sides aligned. . A cross-section that provides a plurality of stepped recesses and U-bolt insertion holes on the back surface of the mounting portion to fix the mounting struts at a plurality of different positions on both sides, and covers the top and bottom surfaces and the front surface of the mounting portion. A substantially U-shaped metal attachment portion cover is detachably provided on the attachment portion, and a U-bolt can be attached to and detached from the rear surface of the attachment portion with the attachment portion cover removed. Item 5. The bidirectional beam antenna according to item 4 . The bidirectional beam antenna is
Two multistage parasitic elements that are provided on the cylindrical unidirectional sides of the two patch antennas and that are gradually reduced in size toward the tip;
Two antenna covers that are attached to the ground plate, house the patch antenna and the multistage parasitic element, and are formed in a tapered shape so as to become narrower toward the distal end in the shape of a rectangular tube on the attachment portion side; With
The bidirectional beam antenna according to claim 2, wherein a direction in which the cylindrical unidirectionality is formed is a longitudinal direction of the bidirectional beam antenna. A transmission system comprising: a plurality of bidirectional beam antennas according to any one of claims 1 to 3 arranged at intervals in the upper, lower, left, and right sides, and transmitting by a spatial diversity method.

Images