JP5787450B2 - Antenna device - Google Patents

Description

  The present invention relates to an antenna device installed in a base station.

  Conventionally, a cellular system that is provided in a base station at the center of a service area, which is a cell composed of a plurality of sectors, and is configured to be able to perform wireless communication between a mobile station located within the service area and the base station. Mobile communication systems are known. In a base station used in this cellular mobile communication system, in order to suppress interference between adjacent base stations, the direction of the front lobe (main beam) in the directivity pattern for each sector of the antenna device of the base station is set. Radio wave confinement technology using a beam tilt that tilts downward from the horizontal direction is used. This technology is a basic technology that forms the basis of mobile communication technology along with diversity technology, and has been applied to mobile communication systems from the first generation to the current fourth generation.

  As a beam tilt method, a mechanical tilt method (for example, refer to Patent Document 1) in which the antenna device is mechanically tilted, and a phase of a signal supplied to a plurality of antenna elements arranged in the vertical direction of the antenna device is electrically adjusted. An electrical tilt method (see, for example, Patent Document 2) is known. In addition, there is also an addition type composite tilt method that realizes a deeper tilt angle (a downward tilt angle from the horizontal direction) by using both methods (see, for example, Patent Document 3).

  In the mechanical tilt method, the antenna device 900 is shown in FIG. 11A so that the longitudinal direction of the array antenna in which a plurality of antenna elements constituting the antenna device 900 are arranged in a line is inclined with respect to the vertical direction V. Is mechanically inclined by a predetermined angle θm. By mechanically tilting the antenna device itself in this way, a beam tilt is realized in which the direction of the front lobe 901f on the desired sector side is tilted downward by a predetermined tilt angle θf (= θm) from the horizontal plane H toward the desired sector. it can. On the other hand, in the back direction opposite to the direction of the front lobe 901 on the desired sector side, the back lobe 901b is tilted in the reverse direction directed upward from the horizontal plane H by a tilt angle θb (= θm). The confinement effect of radio waves in the direction and side direction cannot be expected.

  In the electrical tilt method, the antenna device 900 is installed without being tilted as shown in FIG. 11B so that the longitudinal direction of the array antenna is the vertical direction V, and the phase of the signal supplied to each antenna element of the array antenna is changed. By adjusting, each beam tilt of a predetermined tilt angle θe is realized. Unlike the mechanical tilt method, this electrical tilt method has a feature that the tilt angle θe does not depend on the azimuth angle. Therefore, the same tilt angle θe in any direction of the front lobe 901f, the back lobe 901b, and the side lobe with respect to the desired sector. Beam tilt.

  The addition type composite tilt method is a composite tilt method in which a mechanical tilt method and an electrical tilt method are used in combination as shown in FIG. In this addition type composite tilt method, a mechanical beam tilt (tilt angle: θm) and an electrical beam tilt (tilt angle: θe) are added in the direction of the front lobe 901f, and a deeper tilt angle θf (= θm + θe) is added. ) Beam tilt can be realized. However, as with the mechanical tilt method, it is difficult to increase the downward tilt angle θb (= θe−θm) in the back lobe 901b direction and the downward tilt angle in the side lobe direction. Therefore, a desired radio wave confinement effect cannot be expected in the rear direction and the side direction.

  Of the multiple tilt methods having the characteristics described above, the electric tilt method does not depend on the azimuth angle of the beam tilt angle θe as described above. Therefore, by multiplying the directivity in the vertical plane and the directivity in the horizontal plane. The desired three-dimensional directivity can be realized, and the service area can be easily designed. For this reason, as an antenna device for a base station, an electric tilt type antenna device is frequently used except for special applications.

The electric tilt type antenna device normally used in the base station has a front-back ratio (hereinafter referred to as “F / B”) of about 15 to 20 dB in the directivity pattern, It is affected by non-negligible interference waves that exist in the lateral direction. In order to reduce the influence of the interference wave, it is important for the sector design to further improve the F / B of the antenna device.
In general, in a fixed modulation method using QPSK (Quadrature Phase Shift Keying) of a signal transmitted and received via a base station, if a constant signal-to-noise interference power ratio (hereinafter referred to as “SINR”) is obtained. Further improvement of SINR does not contribute to further improvement of throughput. However, in variable modulation schemes that use multi-level modulation schemes such as 16QAM (Quadrature Amplitude Modulation) and 64QAM that have been applied in recent years, there is a possibility that higher SINR can contribute to further throughput improvement. For this reason, it is extremely effective to further improve the F / B of the antenna device particularly in communication using a variable modulation system.

  However, it is not easy to further improve the 15/20 dB F / B in the physical design of the antenna device in a limited size while facilitating the setting work of the antenna device.

In order to improve the F / B by avoiding an increase in the size of the antenna device, the composite tilt is set so that a predetermined tilt angle is maintained with respect to the desired sector and a deeper tilt angle is provided with respect to the outside of the desired sector. An improved method (hereinafter referred to as “cancellation type composite tilt method”) can be considered. This cancellation type compound tilt method uses both the mechanical tilt method and the electric tilt method in the same manner as the above-described addition type compound tilt method. In the above-described addition type composite tilt method, the overall tilt angle can be set deeper by increasing the mechanical tilt angle and the electrical tilt angle on the front lobe side. On the other hand, in the cancellation type composite tilt method, the mechanical tilt angle and the electrical tilt angle are set to cancel each other on the front lobe side. Specifically, the mechanical tilt angle θm is set so that the front lobe 901f has an upward tilt angle (negative tilt angle) with respect to the horizontal plane H as shown in FIG. On the other hand, as shown in FIG. 12B, the electrical tilt angle θe is set so that the front lobe 901f and the back lobe 901b each have a deep deep tilt angle with respect to the horizontal plane H. As a result, as shown in FIG. 12C, a predetermined total tilt angle θf (= θe−θm) is realized by the front lobe 901f on the desired sector side. On the other hand, the tilt angle in the lateral direction outside the desired sector has only the effect of electrical tilt because mechanical tilt does not work, and is the same as the electrical tilt angle θe. Further, since the electrical tilt angle θe is added to the mechanical tilt angle θ in the rear direction outside the desired sector, the tilt angle θb (= deeper than the tilt angle θf (= θe−θm) of the front lobe 901f. θm + θe> θf) can be realized. As described above, in the cancellation type composite tilt method, a deeper tilt angle can be realized in directions other than the desired sector direction. Therefore, it is applied in limited conditions such as places where you do not want to emit unwanted radio waves in the back direction such as islands and mountain peaks.
However, since the cancellation type composite tilt method involves mechanical tilt in the same manner as the mechanical tilt method and the addition type composite tilt method described above, the installation work is not easy due to the diversification of angle settings when the antenna device is installed.

  The present invention has been made in view of the above problems, and an object of the present invention is to maintain the tilt angle of the front lobe in a desired direction in a directivity pattern at a predetermined angle with a downsized configuration while facilitating installation work. At the same time, an object of the present invention is to provide an antenna device that can deepen the tilt angle of the back lobe on the side opposite to the desired direction.

An antenna device according to the present invention is an antenna device including an array antenna in which a plurality of antenna elements are arranged at a predetermined interval, and a reflecting member provided to face the array antenna, Phase adjustment means for adjusting the phase between the plurality of antenna elements so that the direction of the front lobe in the entire directivity pattern of the array antenna is inclined downward by a predetermined angle from a virtual horizontal plane orthogonal to the longitudinal direction of the array antenna The reflecting member is opposed to the array antenna at a predetermined interval and extends along the longitudinal direction of the array antenna, and is orthogonal to the longitudinal direction of the array antenna and the direction of the front lobe. A sub-reflection portion facing the array antenna from the side, and an edge on the front lobe side of the sub-reflection portion At least in part, it is inclined to the opposite side to the front lobe side lower end side with respect in the longitudinal direction of the array antenna.
According to this antenna device, when the array antenna is installed without being tilted so that the longitudinal direction thereof is the vertical direction, the front lobe in the desired direction is adjusted to a predetermined value by adjusting the phase between the plurality of antenna elements of the array antenna. It can be tilted downward at a tilt angle. Further, by adjusting the phase between the antenna elements, the tilt angle of the back lobe in the direction opposite to the desired direction can be set to the same tilt angle as that of the front lobe. Also, at least a part of the front lobe side edge of the sub-reflecting portion of the reflecting member provided to face the array antenna is opposite to the front lobe side with respect to the lower end side in the longitudinal direction of the array antenna. Leaning on. By tilting at least a part of the edge of the sub-reflecting portion, the diffraction direction of the radio wave on the side opposite to the desired direction of the array antenna can be made downward, and the tilt angle of the back lobe can be deepened.
In addition, since the configuration for increasing the tilt angle of the back lobe is a simple configuration in which at least a part of the edge of the sub-reflection portion is tilted, an increase in the size of the antenna device can be avoided.
Furthermore, since the entire antenna device can be installed without being tilted so that the longitudinal direction of the array antenna is in the vertical direction, the installation work of the antenna device is easy.

In the antenna device, the entire edge of the sub-reflective portion may be inclined to the side opposite to the front lobe side with respect to the lower end side in the direction along the longitudinal direction of the array antenna. According to this antenna device, the effect of lowering the direction of radio wave diffraction on the side opposite to the desired direction of the array antenna is enhanced, so that the tilt angle of the back lobe can be made deeper.
In the antenna device, the shape of the sub-reflecting portion when viewed from the side may be a trapezoid or a triangle. According to this antenna device, it is easy to process the sub-reflecting portion.
In the antenna device, the ratio of the width W in the direction orthogonal to the longitudinal direction of the array antenna when viewed from the side with respect to the length L in the direction along the longitudinal direction of the array antenna of the sub-reflecting portion ( W / L) may be 1/30 or more and 1/20 or less. According to this antenna device, the ratio (W / L) is 1/30 or more while suppressing the size of the sub-reflecting portion in the horizontal direction because the ratio (W / L) is 1/20 or less. The tilt angle of the back lobe can be surely deepened.
In the antenna device, the main reflection portion and the sub reflection portion of the reflection member may be formed of flat plates. According to this antenna device, the processing of the reflecting member is facilitated. Further, when the array antenna and the reflecting member are surrounded by a cylindrical housing member, a space for installing phase adjusting means, a cable, and the like can be secured between the inner wall surface of the housing member and the outer wall surface of the reflecting member.
Moreover, the said antenna apparatus WHEREIN: The lower end part of the said sub-reflection part may be bent inside the said array antenna side. According to this antenna device, since the width of the sub-reflecting portion in the direction orthogonal to the longitudinal direction of the array antenna when the sub-reflecting portion is viewed from the side can be reduced, the size of the reflecting member in the horizontal direction can be reduced. can do.
In the antenna device, at least the sub-reflecting portion of the main reflecting portion and the sub-reflecting portion of the reflecting member may be formed of a curved plate bent so as to surround the array antenna. According to this antenna device, when the array antenna and the reflecting member are surrounded by the cylindrical housing member, the diameter of the housing member can be reduced, and the antenna device can be downsized.

  In this specification, the “directivity pattern” is a pattern in which the relationship between the outward direction centered on the antenna device and the strength of radio wave radiation and reception sensitivity is expressed two-dimensionally or three-dimensionally. is there. The beam-shaped maximum directivity characteristic portion showing the maximum directivity in the directivity pattern is called “front lobe” or “main beam”. The maximum directional characteristic portion located on the back side opposite to the front lobe (main beam) among the plurality of maximal directional characteristics portions showing the maximum directional characteristics in the directivity pattern is referred to as “back lobe”. The maximum directional characteristic portion located on the side surface among the plurality of maximum directional characteristic portions is referred to as a “side lobe”. The “tilt angle” of each of the front lobe, the back lobe, and the side lobe is an inclination angle from the horizontal plane in the direction of the front lobe, the downward angle from the horizontal plane is a positive direction, and the downward angle from the horizontal plane is It is a negative angle. In addition, increasing the tilt angle in the negative direction is referred to as “increasing the tilt angle”.

  According to the present invention, the installation work is easy, the tilt angle of the back lobe on the side opposite to the desired direction is maintained while maintaining the tilt angle of the front lobe in the desired direction in the directivity pattern while avoiding an increase in size. The effect is that the corners can be deepened.

The perspective view which shows the structural example of the antenna apparatus which concerns on one Embodiment of this invention. (A) And (b) is the side view and top view of a sub-reflector which form the reflection member of the antenna device which concerns on this embodiment, respectively. Explanatory drawing which shows typically the mode of the wave front of the electromagnetic wave transmitted / received with the antenna apparatus which concerns on this embodiment. Explanatory drawing which shows the mode of the front lobe and back lobe in the antenna device which concerns on this embodiment. (A) is explanatory drawing of the cell sector structure in the simulation of the antenna device which concerns on this embodiment. (B) is explanatory drawing of the antenna apparatus installed in the base station of a cell center. The graph which shows the simulation result of the directivity pattern in the vertical plane in the antenna apparatus of an Example and each comparative example. The explanatory view which showed the SINR distribution of the periphery of a self-cell at the time of using the antenna apparatus of an Example and a comparative example for a 7 cell 3 sector structure with light and shade. The graph which shows the cumulative probability of the communication capacity in the desired sector of the own cell in an Example and each comparative example. (A) And (b) is the side view and top view of a sub-reflector which concern on a modification, respectively. (A)-(d) is the side view and top view of a sub-reflector which concern on another modification, respectively. (A) is explanatory drawing of the principle of a mechanical tilt system. (B) is an explanatory view of the principle of the electric tilt method. (C) is an explanatory view of the principle of the addition type composite tilt method. (A)-(c) is explanatory drawing of the principle of a cancellation type | mold compound tilt system.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, each embodiment shown below shows an example of the present invention, and the scope of the present invention is not limited to the following embodiment.

  FIG. 1 is a perspective view showing a configuration example of an antenna device according to an embodiment of the present invention. For convenience of explanation, FIG. 1 shows the coordinate axes x, y, and z of the orthogonal coordinate system, and the front lobe direction F and the back lobe direction B in the directivity pattern of the antenna device 100.

  In FIG. 1, the antenna device 100 includes an array antenna 200, a reflection member 300 provided so as to face the array antenna 200, and a radome 400 as a cylindrical housing member. The array antenna 200 has a plurality of antenna elements (for example, dipole antenna elements) 210 arranged in a line at a predetermined interval.

  The reflecting member 300 is integrally formed of a conductive flat plate such as metal, and includes a main reflecting plate 310 as a main reflecting portion and sub reflecting plates 320 and 330 as sub reflecting portions. The main reflector 310 is formed of a rectangular conductive flat plate, faces the array antenna 200 at a predetermined interval, and extends along the longitudinal direction of the array antenna 200. The distance between the main reflector 310 and the array antenna 200 is set to about λ / 4 (λ: wavelength of transmission / reception signal).

  The sub-reflecting plates 320 and 330 are formed of trapezoidal conductive flat plates and face the array antenna 200 from the sides orthogonal to the longitudinal direction of the array antenna 200 and the direction of the front lobe. In addition, end edges 321 and 331 on the front lobe side (opposite to the main reflector side) of the sub reflectors 320 and 330 are opposite to the front lobe side with respect to the lower end side in the longitudinal direction of the array antenna 200. It is inclined to the main reflector side and back lobe side. In the example shown in the figure, the entire edges 321 and 331 of the sub-reflecting plates 320 and 330 are inclined, but some of the edges 321 and 331 may be inclined. The inclination of the end edges 321 and 331 of the sub-reflection plates 320 and 330 will be described later.

  In addition, the antenna device 100 includes a variable distribution phase shifter 500 as a phase adjustment unit. In the variable distribution phase shifter 500, the direction of the front lobe in the entire directivity pattern of the array antenna 200 is inclined downward by a predetermined angle (front tilt angle θf) from a virtual horizontal plane orthogonal to the longitudinal direction of the array antenna 200. The phase is adjusted between a plurality of antenna elements. The variable distribution phase shifter 500 uses, for example, the phase of the radio wave radiated from each antenna element 210, that is, the phase of the transmission signal supplied to each antenna element 210, as a leading phase with respect to the top antenna element, and down Adjustment is made by changing the phase of each antenna element 210 so that the phase is sequentially delayed as it goes. Further, the variable distribution phase shifter 500 sets the phase of the received signal received by each antenna element 210 as a leading phase with respect to the top antenna element, and sequentially delays the phase as it goes down. Each 210 is adjusted by changing the phase. By this adjustment, the front lobe in the vertical plane of the directivity pattern with respect to the radio wave transmitted and received by the entire array antenna 200 is changed from the virtual horizontal plane to a predetermined front tilt with respect to all directions around the array antenna 200. It can be tilted downward by an angle θf (for example, 7 degrees). The variable distribution phase shifter 500 may be built in an empty space in the radome 400 as shown in FIG. 1 or may be provided as an external device separate from the antenna device 100.

  2A and 2B are a side view and a top view of the sub-reflecting plates 320 and 330 forming the reflecting member 300 of the antenna device 100 according to the present embodiment, respectively. The sub-reflecting plates 320 and 330 have a trapezoidal shape when viewed from the side, and the edges 321 and 331 on the front lobe side (the right side in FIG. 2A) are the lengths of the array antenna 200 as described above. Inclined to the side opposite to the front lobe side (main reflector side, back lobe side) with respect to the lower end side in the direction.

  Here, a direction (horizontal direction) orthogonal to the longitudinal direction of the array antenna 200 with respect to the length L in the direction along the longitudinal direction of the array antenna 200 of the sub-reflecting plates 320 and 330 (vertical direction, z-axis direction in the figure). The ratio (W / L) of the width W in the x-axis direction in the drawing is preferably 1/30 or more and 1/20 or less. By setting the ratio (W / L) to 1/20 or less, the ratio (W / L) is set to 1/30 or more while suppressing the width that is the size of the sub-reflecting plates 320 and 330 in the horizontal direction. Thus, the tilt angle of the back lobe can be surely increased. In addition, the inclination angle θs from the vertical direction of the edges 321 and 331 of the reflectors 320 and 330 is preferably 1.8 degrees or more and 3.0 degrees or less. Note that the ratio (W / L) and the inclination angle θs are not limited to the above ranges, and the cell sector configuration and the height of the installation position of the antenna device 100 in the mobile communication system in which the antenna device 100 is used. You may set based on.

  FIG. 3 is an explanatory diagram schematically showing the state of wavefronts of radio waves transmitted and received by the antenna device 100 according to the present embodiment. FIG. 4 is an explanatory diagram showing the state of the front lobe 101f and the back lobe 101b in the antenna device 100 according to the present embodiment.

  On the front F side of the antenna device 100, the direct wave from the array antenna 200 and the reflected wave from the reflectors 310, 320, and 330 are dominant, and a predetermined front from the horizontal plane H as shown by the wavefront Wf in FIG. A front lobe tilt tilted downward by a tilt angle θf (= electrical tilt angle θe) occurs. That is, as shown in FIG. 4, since the front lobe 101f is dominated by radio waves from the array antenna 200 and the main reflector 310, radio waves are radiated at a preset electrical tilt angle θe. The direction of the front lobe 101f is the front tilt direction Ftilt in which the tilt angle θf in the figure is θe.

  On the other hand, on the rear B side of the antenna device 100, the re-radiated wave radiated from the edges 321 and 331 functioning as the secondary re-radiation source of the sub-reflecting plates 320 and 330 rather than the direct wave from the array antenna 200. Becomes dominant. In the antenna device 100 of the present embodiment, since the edges 321 and 331 of the sub-reflecting plates 320 and 330 are inclined at a predetermined inclination angle θs, the mechanical tilt of the above-described cancellation type composite tilt method (FIG. 12 ( It becomes equivalent to a) reference). As a result, a deep backlobe tilt is generated that is tilted downward from the horizontal plane H by a predetermined back tilt angle θb (= θe + θs) as indicated by the wavefront Wb in FIG. That is, as shown in FIG. 4, the back lobe 101b has a deep tilt angle as described above, and the side lobe has an intermediate tilt angle between them. The direction of the back lobe 101b is the back tilt direction Btilt, which is the angle obtained by adding the tilt angle θb in the drawing to θe and θs.

  Next, a computer simulation in which directivity, SINR, and throughput are evaluated in order to confirm the effects of more specific examples in the antenna device 100 according to the present embodiment will be described.

Table 1 is a list of specifications of the simulation.

The inclination angle θs of the edges 321 and 331 of the trapezoidal sub-reflecting plates 320 and 330 constituting the antenna device 100 of the present embodiment is 3 degrees. Further, the cell and sector configurations centering on the base station where the antenna apparatus 100 of the present embodiment is installed are composed of 7 cells (# 0 to # 6) and 3 sectors (#a to #a) as shown in FIG. The configuration is #c). The antenna device 100 of the present embodiment is the same as that shown in FIG. 5A among the three antenna devices 100a to 100c (see FIG. 5B) installed in the base station located in the center of the center cell # 0. An antenna 100a having a sector #a located above as a desired sector is used. As interference waves for a desired wave in sector #a, interference waves in other two sectors #b and #c of the own cell and three sectors (#a to #c) of each cell of adjacent cells (# 1 to # 6) The interference waves for a total of 20 sectors of the interference waves were considered.
Note that the sub-reflecting plate of the antenna device mentioned as the comparative example is rectangular, and the inclination angle of the edge is 0 degree.

  FIG. 6 is a graph showing simulation results of directivity patterns in the vertical plane in the antenna devices of Example (A) and Comparative Example (B). As shown in FIG. 6, the tilt angles in the front direction in the example and the comparative example are all 7 degrees, and the shapes of the directivity patterns are almost the same. On the other hand, in the back direction, the tilt angle in the example (trapezoidal sub-reflecting plate) is 10 degrees, which is deeper than the tilt angle (7 degrees) in the comparative example using the rectangular sub-reflecting plate. I understand that.

  FIGS. 7A and 7B are explanatory diagrams showing the SINR distribution around the own cell in shades when the antenna devices of Example (A) and Comparative Example (B) are used in a 7-cell 3-sector configuration, respectively. It is. The broken line in the figure is the boundary line of the sector of the own cell. FIG. 7 shows that a higher SINR can be obtained in the own sector in the case of the example (trapezoidal sub-reflector) than in the comparative example using the rectangular sub-reflector. In the case of the example (trapezoidal sub-reflector), it can be seen that the SINR value in the adjacent sector is significantly suppressed.

  FIG. 8 is a graph showing the cumulative probability of communication capacity in the desired sector #a of the own cell # 0 in each of the example (A) and the comparative example (B). From FIG. 8, it can be seen that higher throughput can be obtained in the case of the example (trapezoidal sub-reflector) than in the comparative example using the rectangular sub-reflector.

FIGS. 9A and 9B are a side view and a top view of sub-reflecting plates 320 and 330, respectively, according to modified examples. In addition, the same code | symbol is attached | subjected about the part similar to above-mentioned FIG. 2, and description is abbreviate | omitted.
In the configuration example of FIG. 2 described above, the sub-reflecting plates 320 and 330 have a trapezoidal shape when viewed from the side. However, when viewed from the side, as shown in FIGS. The sub-reflection plates 320 and 330 may be formed so as to have a shape.

10A to 10D are top views of sub-reflecting plates 320 and 330 according to other modified examples, respectively. In addition, the same code | symbol is attached | subjected about the part similar to above-mentioned FIG. 2, and description is abbreviate | omitted.
In the configuration example of FIG. 2 described above, the sub-reflecting plates 320 and 330 are each formed in a flat plate shape, but the lower end portions of the sub-reflecting plates 320 and 330 are arranged on the array antenna side as shown in FIG. The sub reflectors 320 and 330 may be formed so as to be bent inward. According to this configuration, the diameter of the cylindrical radome 400 surrounding the array antenna 200 and the reflecting member 300 can be reduced, and the antenna device 100 can be reduced in size.
In the configuration example of FIG. 2 described above, the reflecting member 300 is formed so that the angle formed by the main reflecting plate 310 and the sub-reflecting plates 320 and 330 is 90 degrees. As shown in FIG. Alternatively, the reflecting member 300 may be formed such that the angle φ formed by the main reflecting plate 310 and the sub-reflecting plates 320 and 330 is greater than 90 degrees. The angle φ is set, for example, within a range greater than 90 degrees and 120 degrees or less.
Further, in the configuration example of FIG. 2 described above, the sub-reflecting plates 320 and 330 are each formed in a flat plate shape, but as shown in FIG. 10C, a curved plate bent so as to surround the array antenna. Sub reflectors 320 and 330 may be formed. According to this configuration, the diameter of the cylindrical radome 400 surrounding the array antenna 200 and the reflecting member 300 can be reduced, and the antenna device 100 can be reduced in size.
Further, as shown in FIG. 10D, the reflecting member 300 may be formed in an L-shaped cross section perpendicular to the vertical direction, and the bent portion 310 ′ may be used as the main reflecting portion.

  As described above, according to the present embodiment, the diffraction direction of the radio wave on the side opposite to the desired direction of the array antenna 200 (back lobe side) is made downward due to the inclination of the end edges 321 and 331 of the sub-reflection plates 320 and 330. And the tilt angle θb of the back lobe 101b can be deepened. In addition, since the configuration for increasing the tilt angle θb of the back lobe 101b is a simple configuration in which the edge of the sub-reflection portion is tilted, the increase in size of the antenna device 100 can be avoided. Furthermore, since the entire antenna device 100 can be installed without being tilted so that the longitudinal direction of the array antenna 200 is in the vertical direction, installation work of the antenna device 100 is easy.

  It is noted that the description of the embodiments disclosed herein is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to the present disclosure will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. The present disclosure is therefore not limited to the examples and designs described herein, but should be accorded the widest scope consistent with the principles and novel features disclosed herein.

DESCRIPTION OF SYMBOLS 100 Antenna apparatus 101f Front lobe 101b Back lobe 200 Array antenna 210 Antenna element 300 Reflective member 310 Main reflector 320,330 Sub reflector 321,331 Edge of sub reflector 400 Radome 500 Variable distribution phase shifter

JP-A-2005-051409 Japanese Patent Laid-Open No. 02-174302 JP 2008-011104 A

Claims (7)

An antenna device comprising: an array antenna in which a plurality of antenna elements are arranged at a predetermined interval; and a reflection member provided to face the array antenna,
Phase adjustment means for adjusting the phase between the plurality of antenna elements so that the direction of the front lobe in the entire directivity pattern of the array antenna is inclined downward by a predetermined angle from a virtual horizontal plane orthogonal to the longitudinal direction of the array antenna With
The reflecting member includes a main reflecting portion facing the array antenna at a predetermined interval and extending along a longitudinal direction of the array antenna, and a lateral direction orthogonal to the longitudinal direction of the array antenna and the direction of the front lobe. And a sub-reflecting part facing the array antenna,
At least a part of the front lobe side edge of the sub-reflecting unit is arranged such that a back lobe on the opposite side of the front lobe is inclined downward from the virtual horizontal plane at a tilt angle larger than the front lobe. An antenna device, wherein the antenna device is inclined to the side opposite to the front lobe side with respect to a lower end side in the longitudinal direction of the antenna. The antenna device according to claim 1, wherein
The antenna apparatus according to claim 1, wherein the entire edge of the sub-reflective portion is inclined to the opposite side of the front lobe side with respect to a lower end side in a direction along the longitudinal direction of the array antenna. The antenna device according to claim 2, wherein
The antenna device according to claim 1, wherein a shape of the sub-reflecting portion when viewed from the side is a trapezoid or a triangle. The antenna device according to claim 1 or 3,
The ratio (W / L) of the width W in the direction perpendicular to the longitudinal direction of the array antenna when viewed from the side to the length L in the direction along the longitudinal direction of the array antenna of the sub-reflecting part is 1 An antenna device characterized in that it is / 30 or more and 1/20 or less. The antenna device according to any one of claims 1 to 4,
The antenna device according to claim 1, wherein the main reflection portion and the sub reflection portion of the reflection member are each formed of a flat plate. The antenna device according to claim 5, wherein
The antenna device according to claim 1, wherein a lower end portion of the sub-reflecting portion is bent inward on the array antenna side. The antenna device according to any one of claims 1 to 4,
At least a sub-reflection portion of the main reflection portion and the sub-reflection portion of the reflection member is formed of a curved plate bent so as to surround the array antenna.