Patent Description:
The conventional antenna device includes antenna sections each of which has multiple antenna elements arranged in an array pattern or subarray pattern (see, for example, Patent document <NUM>). Other examples of antenna devices are disclosed in <CIT>.

In order to adjust directions of beams formed by radio waves that are emitted from multiple antenna elements, when the directions of the beams are adjusted using elevation angles and azimuth angles, it may involve complicated calculations.

Accordingly, an object is to provide an antenna device and a feed device that allows a beam direction to be adjusted with a simple calculation.

According to the invention, there is provided an antenna device and a feed device as defined in the appended claims. An antenna device according to one aspect of the disclosure includes an array antenna with multiple antenna elements that are arranged in two dimensions, the multiple antenna elements being arranged along each of a first axis and a second axis. The antenna device includes at least one phase adjusting unit configured to adjust, with respect to a first axial direction, a phase of power supplied to each of the multiple antenna elements. The antenna device includes an image capturing unit configured to capture an image through a fisheye lens. The antenna device includes a position converting unit configured to convert a first position, which is used in the image capturing unit, of a marker included in the image captured by the image capturing unit, into a second position of polar coordinates on a first plane that includes the first axis and the second axis. The antenna device includes an elevation-angle acquiring unit configured to determine, within a second plane that includes the first axis and a third axis, an elevation angle of a projected position relative to the third axis, based on the second position, the projected position being obtained by projecting the first position onto the second plane. The antenna device includes a control unit configured to control the phase adjusting unit such that a direction of a beam radiated through the array antenna is derived from the elevation angle within the second plane.

An antenna device and a feed device that allows a beam direction to be adjusted with a simple calculation are provided.

One or more embodiments in which an antenna device and a feed device according to the present invention are applied are described below.

<FIG> is a diagram illustrating a feed device <NUM> according to an embodiment. The feed device <NUM> includes an array antenna <NUM>, phase shifters <NUM>, a microwave generator <NUM>, a camera <NUM>, and a controller <NUM>. An antenna device 100A according to the embodiment includes components of the feed device <NUM> excepting the microwave generator <NUM>.

In the following description, an XYZ coordinate system is used. A plan view means a view seen from an XY plane. An X-axis is an example of a first axis, a Y-axis is an example of a second axis, and a Z-axis is an example of a third axis. The XY plane is an example of a first plane, and an XZ plane is an example of a second plane.

As an example, the array antenna <NUM> includes a group of four subarrays 110A, 110B, 110C, and 110D. The subarrays 110A to 110D are ranged in an X-axis direction, and each of the subarrays 110A to 110D may include four antenna elements <NUM>, for example. In this case, for example, the array antenna <NUM> includes sixteen antenna elements <NUM>. Each antenna element <NUM> is a rectangular patch antenna in a plan view. The array antenna <NUM> may have a ground plate that is set at a ground potential and that is on the -Z direction side of the antenna elements <NUM>. Note that for example, a center determined based on positions of the sixteen antenna elements <NUM> coincides with the origin of the XYZ coordinate system.

Four phase shifters <NUM> are respectively provided for the four subarrays 110A to 110D, and each of the four phase shifters <NUM> is connected to given antenna elements <NUM> of a corresponding subarray among the subarrays 110A to 110D. In each of the subarrays 110A to 110D, four antenna elements <NUM> are connected in parallel to a corresponding one phase shifter <NUM>. Each phase shifter <NUM> is an example of a phase adjusting unit.

In each of the subarrays 110A to 110D, power having the same phase is supplied to each of the four antenna elements <NUM>. Also, power output from the respective four phase shifters <NUM> to the subarrays 110A to 110D differs from each other in phase. Thus, an angle (elevation angle) of a beam formed by radio waves radiated from the sixteen antenna elements <NUM> can be adjusted within the XZ plane.

A beam output from the array antenna <NUM> is as described in the beam formed by the radio waves radiated from the sixteen antenna elements <NUM>. Also, a beam output from each of the antenna device 100A and the feed device <NUM> is as described in the beam output from the array antenna <NUM>.

The microwave generator <NUM> is connected to each of the four phase shifters <NUM> and supplies microwaves of predetermined power. The microwave generator <NUM> is an example of a radio wave generator. For example, a microwave frequency is <NUM>. Note that in this description, the feed device <NUM> has the configuration that includes the microwave generator <NUM>. However, the microwave is not limiting, and a radio wave of a predetermined frequency may be used.

The camera <NUM> is disposed between the subarray 110B and the subarray 110C. The camera <NUM> includes a fisheye lens <NUM> and a camera body <NUM>. The camera <NUM> is an example of an image capturing unit.

The fisheye lens <NUM> is a lens employing an equidistant projection. For example, a center of the fisheye lens <NUM> coincides with each of the above center determined from the sixteen antenna elements <NUM> and the origin of the XYZ coordinate system. The camera body <NUM> is a portion of the camera <NUM> other than the fisheye lens <NUM>. The camera may be either a camera with a complementary metal oxide semiconductor (CMOS) image sensor or an infrared camera.

The camera <NUM> captures an image with a marker, through the fisheye lens <NUM>, and outputs image data to the controller <NUM>. The marker is attached to a target, to which each of the antenna device 100A and the feed device <NUM> outputs a beam. Each of the antenna device 100A and the feed device <NUM> determines a position of the marker included in a given image captured by the camera <NUM>, and then irradiates the target with a beam.

The controller <NUM> includes a position converting unit <NUM>, an elevation-angle acquiring unit <NUM>, a control unit <NUM>, and a memory <NUM>. The controller <NUM> is implemented by a computer including a central processing unit (CPU) and a memory. The position converting unit <NUM>, the elevation-angle acquiring unit <NUM>, and the control unit <NUM>, which are functionally implemented by a program that the controller <NUM> executes, are illustrated using respective functional blocks. The memory <NUM>, which is a memory of the controller <NUM>, is functionally illustrated.

Hereafter, the position converting unit <NUM>, the elevation-angle acquiring unit <NUM>, the control unit <NUM>, and the memory <NUM> will be described with reference to <FIG> together with <FIG>. <FIG> is a diagram illustrating a polar coordinate system used in the array antenna <NUM>. In <FIG>, only the array antenna <NUM> and the camera <NUM> of the feed device <NUM> are illustrated. Also, in <FIG>, the polar coordinate system in a plane parallel to the XY plane is illustrated.

Moreover, a position of the marker in the XYZ coordinate system is expressed by P1, an elevation angle associated with a line segment connecting the origin O and the position P1 is expressed by θ, and an azimuth angle is expressed by ϕ. The elevation angle is an angle from the +Z direction, the azimuth angle is an angle from the +X direction, and a counterclockwise direction in a plan view is expressed using a positive value. An elevation angle associated with a line segment connecting a position P1a, which is obtained by projecting the position P1 onto the XZ plane, and the origin O, is expressed by θa.

The position P1 is an example of a first position, and the position P1a is an example of a projected position. The origin O is an example of a reference point in the XYZ coordinate system.

Each of the antenna device 100A and the feed device <NUM> adjusts, within only the XZ plane, a given elevation angle of a beam that the array antenna <NUM> outputs. In this regard, it is assumed that a given position of the target is not greatly displaced from the XZ plane (e.g., the given elevation angle from the Z-axis, within the YZ plane, is approximately within the range of ±<NUM> degrees, inclusive). This is because when the given target is at such a position, the beam can be delivered to the given target by simply adjusting the elevation angle of the beam within the XZ plane.

The position converting unit <NUM> performs image processing with respect to an image captured by the camera <NUM>, to thereby convert coordinates of the image to which an equidistant projection is applied and that is obtained through the fisheye lens <NUM>, into polar coordinates on a plane parallel to the XY plane. By the image processing, the position P1, which is used in the array antenna <NUM>, of the marker included in the image captured by the camera <NUM> is converted into a position P2 expressed in polar coordinates on the XY plane. The position P2 is an example of a second position.

The position P2 is expressed with a radius r from the origin O, and a deflection angle ϕ. When a focal length of the fisheye lens <NUM> is given as fL, the radius r is expressed by r = fLθ. The deflection angle ϕ is identical to the azimuth angle ϕ. The position converting unit <NUM> calculates r·cosϕ indicating that the radius r is mapped to the X-axis, by the above-described image processing.

The elevation-angle acquiring unit <NUM> acquires (determines), as the elevation angle θa, a value (r· cosϕ / fL) obtained by dividing an X-coordinate (r· cosϕ) of a mapped position P2a, by the focal length fL of the fisheye lens <NUM>, where the mapped position P2a is obtained by mapping the position P2 to the X-axis. The reason why the elevation angle θa can be obtained in such a manner will be described below.

The control unit <NUM> controls the phase shifters <NUM> such that a given direction of the beam emitted from the array antenna <NUM> is derived from the elevation angle θa within the XZ plane. The elevation angle θa is obtained by the elevation-angle acquiring unit <NUM>. The control unit <NUM> performs an output control of the microwave generator <NUM>, an imaging control of the camera <NUM>, and the like.

The memory <NUM> stores a program to be executed when the position converting unit <NUM>, the elevation-angle acquiring unit <NUM>, and the control unit <NUM> perform processing. The memory <NUM> stores data such as data to be used when the program is executed, data to be generated when the program is executed, and image data that the camera <NUM> acquires.

Hereafter, a method for determining the elevation angle θa will be described.

When the azimuth angle ϕ and the elevation angle θ are used, the elevation angle θa can be determined, as expressed by Equation (<NUM>) below, by taking into account the geometric relationship between the position P1 and the position P1a. <NUM>] <MAT> When Equation (<NUM>) is expanded, Equation (<NUM>) is obtained. <NUM>] <MAT> Here, if the elevation angle θ is sufficiently small, "tanθ ≒ θ" is satisfied; if the azimuth angle ϕ is sufficiently small, "cosϕ ≒ <NUM>" is satisfied; and, if the azimuth angle ϕ is close to <NUM> degrees, "cosϕ ≒ <NUM>" is satisfied, accordingly, then Equation (<NUM>) can be transformed into Equation (<NUM>). <NUM>] <MAT> In other words, if the position of a given target is not displaced greatly from the XZ plane, the elevation angle θa can be approximated as expressed by Equation (<NUM>).

Further, as described above, when the focal length fL of the fisheye lens <NUM> is given as fL, the radius r is expressed by Equation (<NUM>) below. <MAT> From Equation (<NUM>) and Equation (<NUM>), the elevation angle θa can be expressed by Equation (<NUM>) below. <MAT> Thus, the elevation angle θa can be approximated using Equation (<NUM>).

As described above, when a given elevation angle of the beam from the array antenna <NUM> is adjusted within only the XZ plane, the position P2 is calculated by converting coordinates of the position P1, which are obtained by an equidistance projection, into polar coordinates on a plane parallel to the XY plane, and further, an X-coordinate (r·cosϕ) of a given protected position P2a is divided by the focal length fL of the fisheye lens <NUM>, where the given projected position P2a is obtained by mapping the position P2 to the X axis. Thus, the elevation angle θa (= r▪cosϕ / fL) can be determined.

Accordingly, an antenna device 100A and a feed device <NUM> that allows a beam direction to be adjusted with a simple calculation can be provided.

Also, each of the antenna device 100A and the feed device <NUM> adjusts a given elevation angle of the beam output from the array antenna <NUM>, within only the XZ plane, and thus the number of phase shifters <NUM> is one-fourth of the number of phase shifters in a case where the elevation angle is adjusted within both the XZ plane and the YZ plane. Accordingly, the antenna device 100A and the feed device <NUM> can be inexpensively implemented.

Note that in the above description, the center of the fisheye lens <NUM> coincides with the center determined from the sixteen antenna elements <NUM>. However, the center of the fisheye lens <NUM> may be displaced from the above center of the sixteen antenna elements <NUM>. In this case, a coordinates origin used in determining the phase for controlling the array antenna may be displaced by an amount of displacement.

<FIG> is a diagram illustrating an example of how the feed device <NUM> is applied. For example, the feed device <NUM> is provided in a vehicle, and a target antenna <NUM> is provided on an inner wall <NUM> of a tunnel. A marker <NUM> is attached to the antenna <NUM>. The marker <NUM> includes a retroreflective reflector, a mirror ball, or the like.

When the vehicle travels in the +X direction, the camera <NUM> is used to convert coordinates of a position of the marker <NUM> into polar coordinates in a plane parallel to an XY plane, and then a beam is delivered to the antenna <NUM> by using a given elevation angle θa (= r▪cosϕ / fL), which is determined by dividing an X-coordinate (r▪cosϕ) of a mapped position (mapped position corresponding to P2a), by the focal length fL of the fisheye lens <NUM>, where the mapped position is obtained by mapping the position of the polar coordinates onto the X-axis.

For example, the antenna <NUM>, a sensor, a rectenna, and a wireless communication module are secured to a fixing portion for fixing an infrastructural object, such as a jet fan or a sign, to the inner wall <NUM> of the tunnel, where the facility object is attached to the inner wall <NUM> of the tunnel, and the sensor monitors loosening of a bolt or the like used at the fixing portion. In such a manner, when the feed device <NUM> irradiates the antenna <NUM> with a beam, while the vehicle is traveling, the rectenna connected to the antenna <NUM> generates power to thereby cause the wireless communication module to start. Then, the wireless communication module radiates a signal indicating the output of the sensor, and the signal is thereby received on the vehicle side. Thus, a fixed state of the infrastructural object can be inspected while the vehicle is traveling.

In this case, a given signal indicating the output of the sensor, which is radiated by the wireless communication module, may be received through the array antenna <NUM>.

Also, a given X-coordinate (r▪cosϕ) of a given mapped position (mapped position corresponding to P2a) is determined by mapping a given position of the antenna <NUM>, which is shifted from the XZ plane, to the X-axis, and then a beam is adjusted by using a given value (r▪cosϕ / fL) obtained by dividing the given X-coordinate (r▪cosϕ) by the focal length fL of the fisheye lens <NUM>, where the given value (r▪cosϕ / fL) is used as a given elevation angle θa. Thus, even when the vehicle traveling in the X-axis direction shifts toward either a positive side or negative side of the Y-axis, displacement due to the shift is reduced, thereby enabling the given elevation angle θa to be determined.

In this description, the case where the feed device <NUM> (antenna device 100A) communicates with the wireless communication module provided on the inner wall <NUM> of the tunnel has been described with reference to <FIG>. However, the wireless communication module is not limited to being provided on the inner wall <NUM> of the tunnel, and may be provided at various positions, or the like. In such a manner, the feed device <NUM> (antenna device 100A) can be used as a communication device.

Although the antenna device and feed device according to the illustrative embodiment of the present invention have been described, the present invention is not limited to the embodiment disclosed specifically.

Claim 1:
An antenna device(100A) comprising:
an array antenna (<NUM>) with multiple antenna elements (<NUM>) that are arranged in two dimensions, the multiple antenna elements (<NUM>) being arranged along each of a first axis (X) and a second axis (Y);
at least one phase adjusting unit (<NUM>) configured to adjust, with respect to a first axial direction, a phase of power supplied to each of the multiple antenna elements (<NUM>); a fisheye lens (<NUM>) ;
an image capturing unit (<NUM>) configured to capture an image through the
fisheye lens (<NUM>);
a position converting unit (<NUM>) configured to convert a first position (P1), which is used in the image capturing unit (<NUM>), of a marker (<NUM>) included in the image captured by the image capturing unit (<NUM>), into a second position (P2) of polar coordinates on a first plane (XY) that includes the first axis (X) and the second axis (Y), the marker (<NUM>) being attached to a target to be irradiated with a beam through the array antenna (<NUM>);
an elevation-angle acquiring unit (<NUM>) configured to determine, within a second plane (XZ) that includes the first axis (X) and a third axis (Z), an elevation angle (θa) of a projected position (P1a) relative to the third axis (Z), based on the second position (P2) and based on a geometric relationship between the first position (P1) and the projected position (P1a), the projected position (P1a) being obtained by projecting the first position (P1) onto the second plane (XZ); and
a control unit (<NUM>) configured to control the phase adjusting unit (<NUM>) such that a direction of a beam radiated through the array antenna (<NUM>) is derived from the elevation angle (θa) within the second plane (XZ).