Antenna device

Abstract

To provide a small-sized right / left circularly polarized wave shared antenna at low cost.SOLUTION: An antenna device includes a first cross dipole antenna and a second cross dipole antenna. The first cross dipole antenna includes a pair of L-shaped first antenna elements facing each other across an antenna central axis, and radiates a first circularly polarized radio wave rotating in a first direction. The second cross dipole antenna includes a pair of L-shaped second antenna elements facing each other across the antenna central axis and adjacent to the pair of first antenna elements, and radiates a second circularly polarized radio wave rotating in a second direction opposite to the first direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an antenna device, and more particularly to a circular polarization shared antenna capable of simultaneously transmitting and receiving right-handed circularly polarized radio waves and left-handed circularly polarized radio waves.

Background Art

[0002] When communicating with a rocket or a satellite by radio waves, since the direction of the antenna changes, circularly polarized radio waves are used so as to cope with this change. At this time, two circularly polarized waves, a right-handed circularly polarized wave and a left-handed circularly polarized wave, are used according to the communication situation or the uplink and the downlink.

[0003] As a means for transmitting and receiving two circularly polarized radio waves, there is a case where a right-handed circularly polarized antenna and a left-handed circularly polarized antenna are arranged side by side. In this case, the area occupied by the antennas becomes large.

[0004] As another means for transmitting and receiving two circularly polarized radio waves, there is the use of a circular polarization shared antenna capable of simultaneously transmitting and receiving a right-handed circularly polarized wave and a left-handed circularly polarized wave. This solves the problem of using two types of antennas, a right-handed circularly polarized antenna and a left-handed circularly polarized antenna. Examples of the circular polarization shared antenna include those disclosed in Patent Document 1, Patent Document 2, and Patent Document 3.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] Since the circular polarization shared antenna of Patent Document 1 is composed of a large number of layered structures with a complex shape, there is a problem that the manufacturing cost becomes high. In addition, since the circular polarization shared antenna of Patent Document 2 is an array antenna composed of a power divider, a circular polarization generator, and a polarization splitter in addition to the antenna radiation element, there is a problem that the number of components increases and the manufacturing cost becomes high. Furthermore, since the circular polarization shared antenna of Patent Document 3 is composed of a conical horn and a waveguide, there is a problem that it becomes long in the axial direction and the antenna becomes large-sized.

[0007] In view of the above circumstances, an object of the present invention is to provide a low-cost and small-sized right- and left-handed circular polarization shared antenna.

Means for Solving the Problems

[0008] An antenna device according to an aspect of the present invention includes a first cross dipole antenna and a second cross dipole antenna. The first cross dipole antenna has a pair of first antenna elements having an L shape facing each other across the antenna central axis, and radiates a first circularly polarized radio wave rotating in a first direction. The second cross dipole antenna has a pair of second antenna elements having an L shape facing each other across the antenna central axis and adjacent to the pair of first antenna elements, and radiates a second circularly polarized radio wave rotating in a second direction opposite to the first direction.

[0009] In the above antenna device, the antenna is configured by two antennas having a simple structure of a cross dipole antenna. Further, the first cross dipole antenna and the second cross dipole antenna each have a common antenna central axis. Therefore, a low-cost and small-sized right- and left-handed circular polarization shared antenna can be provided.

[0010] At least a part of the pair of first antenna elements and at least a part of the pair of second antenna elements may be located on the same plane, respectively.

[0011] The pair of first antenna elements and the pair of second antenna elements may each have two shaft portions that form the L shape and have different lengths.

[0012] The first cross dipole antenna further includes a first power supply cable having an internal conductor connected to one of the pair of first antenna elements and an external conductor connected to the other antenna element, and the second cross dipole antenna may further include a second power supply cable having an internal conductor connected to one of the pair of second antenna elements and an external conductor connected to the other antenna element.

[0013] The antenna device may further include a support substrate that supports the first cross dipole antenna and the second cross dipole antenna.

[0014] The antenna device may further include a reflector disposed apart from the first cross dipole antenna and the second cross dipole antenna.

[0015] The reflector may have any shape such as a planar shape or a parabolic shape.

Advantages of the Invention

[0016] According to the present invention, a low-cost and small right-hand and left-hand circular polarization shared antenna can be provided.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0019] <First Embodiment> FIG. 1 is a schematic perspective view showing the configuration of the antenna device 100 according to the first embodiment of the present invention, and FIG. 2 is a plan view of the main part of the antenna device 100 viewed from the positive z-axis direction.

[0020] In each figure, the x-axis, y-axis, and z-axis indicate three mutually orthogonal axis directions, and the z-axis corresponds to the antenna central axis of the antenna device 100. Also, in the following description, the intersection (origin) of the x-axis, y-axis, and z-axis is also referred to as the antenna center O.

[0021] [Overall Configuration of Antenna Device] As shown in FIG. 1, the antenna device 100 includes a first cross dipole antenna 11, a second cross dipole antenna 12, and a support 13 that supports these first and second cross dipole antennas 11 and 12.

[0022] The first cross dipole antenna 11 has a pair of first antenna elements 11A and 11B and a first power supply cable 110. The first cross dipole antenna 11 is configured to be able to radiate a first circularly polarized radio wave (for example, a right-handed circularly polarized radio wave) that rotates in a first direction (for example, clockwise).

[0023] The first antenna elements 11A and 11B each have two shaft portions x1 and y1 parallel to the x-axis direction and the y-axis direction forming an L shape, and are arranged on the support 13 so as to face each other across the antenna central axis (z-axis). The first antenna elements 11A and 11B are composed of a metal such as copper or aluminum formed on the surface of the support 13 (element mounting surface 131).

[0024] The first power supply cable 110 is a coaxial cable having a core wire (inner conductor) 110a connected to the first antenna element 11A on one side and a shield wire (outer conductor) 110b connected to the first antenna element 11B on the other side. The first power supply cable 110 connects between the first antenna elements 11A and 11B and a transceiver (not shown).

[0025] The second cross dipole antenna 12 has a pair of second antenna elements 12A and 12B and a second power supply cable 120. The second cross dipole antenna 11 is configured to be able to radiate a second circularly polarized radio wave (for example, a left-handed circularly polarized radio wave) that rotates in a second direction (for example, counterclockwise) opposite to the first direction.

[0026] The second antenna elements 12A and 12B each have two shaft portions x2 and y2 parallel to the x-axis direction and the y-axis direction forming an L shape, face each other across the antenna central axis (z-axis), and are arranged on the support 13 so as to be adjacent to the first antenna elements 11A and 11B. The second antenna elements 12A and 12B are composed of a metal such as copper or aluminum formed on the surface of the support 13 (element mounting surface 131).

[0027] More specifically, as shown in FIG. 2, the first antenna elements 11A and 11B are respectively arranged in the first quadrant and the third quadrant in the xy orthogonal coordinate plane, and the second antenna elements 12A and 12B are respectively arranged in the second quadrant and the fourth quadrant.

[0028] The second power supply cable 120 is a coaxial cable having a core wire (inner conductor) 120a connected to the second antenna element 12A on one side and a shield wire (outer conductor) 120b connected to the second antenna element 12B on the other side. The second power supply cable 120 connects between the second antenna elements 12A and 12B and a transceiver (not shown).

[0029] The support 13 is a dielectric substrate having an element mounting surface 131 parallel to the xy plane. The support 13 can be composed of, for example, a dielectric layer of a multilayer wiring board, and by patterning the conductor layer formed on one surface (element mounting surface 131) thereof into a predetermined shape, a pair of first antenna elements 11A and 11B and a pair of second antenna elements 12A and 12B are formed.

[0030] On the other hand, on the back surface of the support 13 opposite to the element mounting surface 131, a connector (not shown) connected to the first power supply cable 110 and the second power supply cable 120, and a plurality of wiring patterns L1 to L4 connecting between these power supply cables 110 and 120 and the antenna elements 11A, 11B, 12A, and 12B are formed.

[0031] The wiring pattern L1 connects between the core wire 110a of the first power supply cable 110 and the first antenna element 11A on one side, and the wiring pattern L2 connects between the shield wire 110b of the first power supply cable 110 and the first antenna element 11B on the other side. The wiring pattern L3 connects between the core wire 120a of the second power supply cable 120 and the second antenna element 12A on one side, and the wiring pattern L4 connects between the shield wire 120b of the second power supply cable 120 and the second antenna element 12B on the other side.

[0032] The wiring patterns L1 and L2 are respectively connected to the L-shaped joints (connection parts of the shaft parts x1 and y1) xy1a and xy1b of the first antenna elements 11A and 11B through vias or through holes (interlayer connection parts) not shown that penetrate the support 13 in the thickness direction. The wiring patterns L3 and L4 are respectively connected to the L-shaped joints (connection parts of the shaft parts x2 and y2) xy2a and xy2b of the second antenna elements 12A and 12B through vias or through holes (interlayer connection parts) not shown that penetrate the support 13 in the thickness direction.

[0033] [Details of the First and Second Antenna Elements] Next, details of the first and second antenna elements 11A, 11B, 12A, and 12B will be described.

[0034] As shown in FIG. 2, the first antenna elements 11A and 11B have a shape symmetric with respect to the antenna center O, and the L-shaped joints xy1a and xy1b of each are located on the straight line of y = x.

[0035] Here, for the first antenna element 11A on one side, the joint xy1a is located at the coordinates (Px1, Py1), the shaft part x1 extends parallel to the x-axis in the +x direction from the joint xy1a, the shaft part y1 extends parallel to the y-axis in the +y direction from the joint xy1a, and the length (Lx1) of the shaft part x1 is shorter than the length (Ly1) of the shaft part y1 (Lx1 < Ly1). Also, for the first antenna element 11B on the other side, the joint xy1b is located at the coordinates (-Px1, -Py1), the shaft part x1 extends parallel to the x-axis in the -x direction from the joint xy1b, the shaft part y1 extends parallel to the y-axis in the -y direction from the joint xy1b, and the length (Lx1) of the shaft part x1 is shorter than the length (Ly1) of the shaft part y1 (Lx1 < Ly1).

[0036] Similarly, the second antenna elements 12A and 12B have a shape symmetric with respect to the antenna center O, and the L-shaped joints xy2a and xy2b of each are located on the straight line of y = -x. That is, the pair of first antenna elements 11A and 11B and the pair of second antenna elements 12A and 12B are in a mutually orthogonal positional relationship.

[0037] Here, for the second antenna element 12A on one side, the joint point xy2a is located on the coordinates (Px2, -Py2), the shaft portion x2 extends from the joint point xy2a in the +x direction parallel to the x-axis, the shaft portion y2 extends from the joint point xy2a in the -y direction parallel to the y-axis, and the length (Lx2) of the shaft portion x2 is shorter than the length (Ly2) of the shaft portion y2 (Lx2 < Ly2). For the second antenna element 12B on the other side, the joint point xy2b is located on the coordinates (-Px2, Py2), the shaft portion x2 extends from the joint point xy2b in the -x direction parallel to the x-axis, the shaft portion y2 extends from the joint point xy2b in the +y direction parallel to the y-axis, and the length (Lx2) of the shaft portion x2 is shorter than the length (Ly2) of the shaft portion y2 (Lx2 < Ly2).

[0038] Furthermore, in the example of FIG. 2, the shaft portion x1 of the first antenna elements 11A and 11B is longer than the shaft portion x2 of the second antenna elements 12A and 12B (Lx1 > Lx2), and the shaft portion y1 of the first antenna elements 11A and 11B is longer than the shaft portion y2 of the second antenna elements 12A and 12B (Ly1 < Ly2).

[0039] The above dimensions Lx1, Ly1, Lx2, Ly2, Px1, Py1, Px2, and Py2 are arbitrarily determined so as to obtain a predetermined impedance and a predetermined circularly polarized wave of rotation at the frequency used. Note that Lx1 and Lx2 may have the same value. Also, Ly1 and Ly2 may have the same value. Also, Px1 and Px2 are not limited to the case where they have the same value and may have different values. Also, Py1 and Py2 are not limited to the case where they have the same value and may have different values.

[0040] In the antenna device 100 of the present embodiment configured as described above, the first cross-dipole antenna 11 and the second cross-dipole antenna 12 are each provided with a dedicated first power supply cable 110 and a second power supply cable 120. When the first cross-dipole antenna 11 is a right-handed circularly polarized wave antenna, the second cross-dipole antenna 12 becomes a left-handed circularly polarized wave antenna. Therefore, transmission and reception of right-handed polarized waves are possible via the first power supply cable 110, and transmission and reception of left-handed polarized waves are possible via the second power supply cable 120. Conversely, when the first cross-dipole antenna 11 is a left-handed circularly polarized wave antenna, the second cross-dipole antenna 12 becomes a right-handed circularly polarized wave antenna. Therefore, transmission and reception of left-handed polarized waves are possible via the first power supply cable 110, and transmission and reception of right-handed polarized waves are possible via the second power supply cable 120.

[0041] The present invention configures an antenna by arranging two antennas with a simple structure of a cross-dipole antenna on a plane and connecting a power supply cable to each antenna. Therefore, the antenna can be configured at low cost. Further, according to the present embodiment, since the antenna centers of the first cross-dipole antenna 11 and the second cross-dipole antenna 12 coincide, it is possible to miniaturize a circular polarization shared antenna that can simultaneously transmit and receive right-handed circularly polarized waves and left-handed circularly polarized waves, and it is also possible to align the phases of the right-handed circularly polarized waves and the left-handed circularly polarized waves.

[0042] Furthermore, according to the present embodiment, since the first cross-dipole antenna 11 and the second cross-dipole antenna 12 are arranged on the same plane, the antenna device 100 can also be made thinner.

[0043] In FIG. 1, a support 13 for installing a first cross-dipole antenna 11 and a second cross-dipole antenna 12 is shown. However, when the first cross-dipole antenna 11 and the second cross-dipole antenna 12 can be stably configured respectively (for example, when each antenna element 11A, 11B, 12A, 12B is formed of a relatively rigid metal plate), the installation of the support 13 can be omitted. In this case, instead of the wiring patterns L1 to L4, for example, between the first cross-dipole antenna 11 and the first power supply cable 110, and between the second cross-dipole antenna 12 and the second power supply cable 120 are respectively connected via a cable, a wire, or the like.

[0044] (Application Example 1) FIG. 3 shows the analytical values of (1) right-handed circular polarization and (2) left-handed circular polarization in the xz plane of the antenna pattern of the antenna device 100 of the present embodiment when the frequency of the radio wave is 2280 MHz, Lx1 = Lx2 = 28 mm, Ly1 = Ly2 = 30 mm, Px1 = Py1 = Px2 = Py2 = 1 mm, represented in polar coordinates.

[0045] As shown in FIGS. 3(1) and (2), since the patterns of right-handed circular polarization and left-handed circular polarization of the antenna device 100 according to the present embodiment are substantially the same, it can be seen that the antenna device 100 according to the present embodiment is a right / left-handed circular polarization antenna.

[0046] <Second Embodiment> FIG. 4 is a schematic perspective view showing the configuration of an antenna device 200 according to the second embodiment of the present invention. Hereinafter, the configurations different from those of the first embodiment will be mainly described, and the same configurations as those of the first embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted or simplified.

[0047] In the antenna device 200 of the present embodiment, a reflector 23 is installed, and it is different from the first embodiment in that a pair of first antenna elements 11A, 11B and a pair of second antenna elements 12A, 12B are installed above the reflector 23.

[0048] The pair of first antenna elements 11A and 11B and the pair of second antenna elements 12A and 12B are configured in the same manner as in the first embodiment, and are each arranged on the same plane parallel to the xy plane around the antenna central axis (z-axis).

[0049] The reflector 23 is a square metal plate with a side length of L parallel to the xy plane, and its center 23c is arranged at a distance H from the antenna center O in the z-axis direction.

[0050] The first antenna elements 11A and 11B are connected to a first power supply cable (not shown), thereby constituting a first cross dipole antenna 11 that radiates a first circularly polarized radio wave (right-handed circularly polarized radio wave) rotating in a first direction (for example, clockwise). The second antenna elements 12A and 12B are connected to a second power supply cable (not shown), thereby constituting a second cross dipole antenna 12 that radiates a second circularly polarized radio wave (left-handed circularly polarized radio wave) rotating in a second direction (for example, counterclockwise). Thus, similar to the first embodiment, a circular polarization shared antenna capable of simultaneously transmitting and receiving a right-handed circularly polarized radio wave and a left-handed circularly polarized radio wave with the antenna centers O coinciding can be obtained.

[0051] Note that the first antenna elements 11A and 11B and the second antenna elements 12A and 12B can be arranged directly above the reflector 23 via a columnar body such as a support column (not shown) erected from near the center 23c of the reflector 23 to near the first and second cross dipole antennas 11 and 12. In this case, the first and second power supply cables can be connected to the first antenna elements 11A and 11B and the second antenna elements 12A and 12B through the inside of the columnar body. Also, as described above, the first antenna elements 11A and 11B and the second antenna elements 12A and 12B can be formed of, for example, a relatively rigid metal plate, so that their forms can be maintained without the need for a support.

[0052] (Application Example 2) FIG. 5 shows the analytical values of (1) right-handed circular polarization and (2) left-handed circular polarization in the xz plane of the antenna pattern of the antenna device 200 according to the present embodiment, presented in polar coordinates. Here, the radio wave frequency is 2280 MHz, Lx1 = Lx2 = 28 mm, Ly1 = Ly2 = 30 mm, Px1 = Py1 = Px2 = Py2 = 1 mm, L = 100 mm, and H = 30 mm.

[0053] As shown in FIGS. 5(1) and (2), since the patterns of right-handed circular polarization and left-handed circular polarization of the antenna device 200 according to the present embodiment are substantially the same, it can be seen that the antenna device 200 according to the present embodiment is a right / left-handed circular polarization antenna.

[0054] <Third Embodiment> FIG. 6 is a schematic perspective view showing the configuration of an antenna device 300 according to the third embodiment of the present invention. Hereinafter, the configurations different from those of the first embodiment will be mainly described, and the same configurations as those of the first embodiment will be denoted by the same reference numerals, and their detailed descriptions will be omitted or simplified.

[0055] The antenna device 300 of the present embodiment is different from the first embodiment in that a reflector 33 is installed, and a pair of first antenna elements 11A and 11B and a pair of second antenna elements 12A and 12B are installed above the reflector 33.

[0056] The pair of first antenna elements 11A and 11B and the pair of second antenna elements 12A and 12B are configured in the same manner as in the first embodiment, and are respectively arranged on the same plane parallel to the xy plane around the antenna central axis (z-axis).

[0057] The reflector 33 is a parabolic reflector filled with a dielectric 34. In the present embodiment, the first and second cross-dipole antennas 11 and 12 are applied as the primary radiators of the parabolic reflector. Note that the dielectric 34 may be omitted as necessary.

[0058] Similar to the second embodiment, the first antenna elements 11A and 11B and the second antenna elements 12A and 12B can be arranged at a position directly above the bottom of the reflector 33 via a columnar body such as a support column (not shown) erected from the bottom of the reflector 33 to the vicinity of the first and second cross-dipole antennas 11 and 12. In this case, the first and second power supply cables can be connected to the first antenna elements 11A and 11B and the second antenna elements 12A and 12B through the inside of the columnar body. Also, as described above, the first antenna elements 11A and 11B and the second antenna elements 12A and 12B are formed of, for example, a relatively rigid metal plate, so that their forms can be maintained without the need for a support.

[0059] (Application Example 3) FIG. 7 shows the analytical values of the (1) right-handed circularly polarized wave and (2) left-handed circularly polarized wave in the xz plane of the antenna pattern of the antenna device 300 of the present embodiment in polar coordinate display. Here, the frequency of the radio wave is 2280 MHz, Lx1 = Lx2 = 15 mm, Ly1 = Ly2 = 20 mm, Px1 = Py1 = Px2 = Py2 = 1 mm, the aperture diameter D of the reflector 33 is 96 mm, the aperture surface height T of the reflector 33 is 28 mm, and the primary radiator depth F is 7 mm. Also, the dielectric 34 is made of high-density polyethylene.

[0060] As shown in FIGS. 7(1) and (2), since the patterns of the right-handed circularly polarized wave and the left-handed circularly polarized wave of the antenna device 300 according to the present embodiment almost coincide, it can be seen that the antenna device 300 according to the present embodiment is a right / left-handed circularly polarized antenna.

[0061] The embodiments of the present invention have been described above, but the present invention is not limited only to the above-described embodiments, and various modifications can of course be made.

[0062] For example, in each of the above embodiments, in order to block the unbalanced current flowing through the first and second power supply cables 110 and 120, a balun may be installed on the first and second power supply cables 110 and 120. Further, in order to compensate for the difference in the length and characteristics of the first and second power supply cables 110 and 120, a phase shifter or an attenuator may be installed between the first or second power supply cable 110 or 120 and the transceiver device. Note that it is common knowledge among those skilled in the art to install a balun, a phase shifter, or an attenuator as needed when manufacturing an antenna. Therefore, the details of their installation are omitted in this specification.

[0063] Also, in each of the above embodiments, the entire first antenna elements 11A and 11B and the entire second antenna elements 12A and 12B are arranged on the same plane, respectively. However, at least a part of them may be arranged on the same plane. For example, the joining points xy1a and xy1b of the first antenna elements 11A and 11B and the joining points xy2a and xy2b of the second antenna elements 12A and 12B do not have to be on the same xy plane (the z coordinates may be different). Also, the distance between the joining points xy1a and xy1b of the first antenna elements 11A and 11B and the distance between the joining points xy2a and xy2b of the second antenna elements 12A and 12B are not limited to being the same and may be different.

[0064] Furthermore, in the above embodiments, the shaft portions x1 of the first antenna elements 11A and 11B and the shaft portion x2 of the second antenna elements 12A and 12B are formed parallel to the x-axis, respectively. However, the present invention is not limited to this. The shaft portions x1 and x2 may be parallel or non-parallel to the x-axis. Similarly, for the shaft portions y1 and y2, they are not limited to being parallel to the y-axis, and the shaft portions y1 and y2 may be parallel or non-parallel to the y-axis.

Description of Reference Numerals

[0065] 11…First cross dipole antenna 11A, 11B…First antenna elements 12…Second cross dipole antenna 12A, 12B…Second antenna elements 13…Support 23, 33…Reflector 100, 200, 300…Antenna device 110…First power supply cable 120…Second power supply cable

Claims

1. A first cross - dipole antenna having a pair of L - shaped first antenna elements facing each other across an antenna central axis and radiating a first circularly polarized radio wave rotating in a first direction, A second cross - dipole antenna having a pair of L - shaped second antenna elements facing each other across the antenna central axis and adjacent to the pair of first antenna elements and radiating a second circularly polarized radio wave rotating in a second direction opposite to the first direction An antenna device comprising the above.

2. The antenna device according to claim 1, At least a part of the pair of first antenna elements and at least a part of the pair of second antenna elements are located on the same plane respectively An antenna device.

3. The antenna device according to claim 2, The pair of first antenna elements and the pair of second antenna elements each have two shaft portions forming the L - shape and having different lengths An antenna device.

4. The antenna device according to claim 3, The first cross - dipole antenna further has a first power - supply cable having an internal conductor connected to one of the pair of first antenna elements and an external conductor connected to the other first antenna element, The second cross - dipole antenna further has a second power - supply cable having an internal conductor connected to one of the pair of second antenna elements and an external conductor connected to the other second antenna element An antenna device.

5. The antenna device according to claim 1, Further comprising a support substrate for supporting the first cross - dipole antenna and the second cross - dipole antenna An antenna device.

6. The antenna device according to claim 1, Further comprising a reflector arranged separately from the first cross - dipole antenna and the second cross - dipole antenna An antenna device.

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