Antenna system and array antenna system

Abstract

An antenna (10) is provided with: a looped antenna element (11) formed by a conductor having open ends on both ends; and an annular first grounding conductor (12) which is connected to one open end of the antenna element (11) and is disposed and closed so as to surround an outer periphery of the antenna element (11).

Description

[Technical field]

[0001] The present disclosure relates to an antenna, an antenna system, an array antenna, and an array antenna system. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a module has been disclosed that includes a coil antenna formed of a spiral pattern coil for transmitting and receiving signals through non-contact communication with a non-contact IC card (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-269386 A Summary of the Invention [Problem to be solved by the invention]

[0004] When power is supplied to an antenna included in a module via a cable such as a coaxial cable, the ground conductor of such a cable may be connected to the ground conductor provided in the module. On the other hand, as disclosed in Patent Document 1, the antenna included in the module may also be connected to the above-mentioned ground conductor provided in the module. In such a case, a current leaking from the antenna to the ground conductor of the module flows into the ground conductor of the cable. This may cause the radiation characteristics of the antenna to be affected by the cable.

[0005] Therefore, the present disclosure provides an antenna etc. that can improve radiation characteristics. [Means for solving the problem]

[0006] An antenna according to one embodiment of the present disclosure comprises a loop-shaped antenna element formed by a conductor having open ends at both ends, and a ring-shaped first ground conductor connected to one of the open ends of the antenna element and arranged in a closed manner so as to surround the outer periphery of the antenna element. Effect of the Invention

[0007] According to the antenna etc. according to the present disclosure, radiation characteristics can be improved. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a plan view of the antenna system according to the first embodiment. [Figure 2A] FIG. 2A is a diagram showing a simulation result of a current distribution in an antenna system according to a comparative example. [Figure 2B] FIG. 2B is a diagram showing a simulation result of a current distribution in the antenna system according to the first embodiment. [Diagram 3] FIG. 3 is a plan view of the array antenna system according to the second embodiment. [Figure 4] FIG. 4 is a circuit configuration diagram showing an example of the phase control section according to the second embodiment. As shown in FIG. [Diagram 5] FIG. 5 is a circuit configuration diagram showing an example of a part of the phase control section according to the second embodiment. As shown in FIG. [Figure 6] FIG. 6 is a graph showing an example of the phase characteristic of each phase shifter in the phase control section according to the second embodiment. [Figure 7] FIG. 7 is a graph showing the directivity pattern when the phase difference of the array antenna according to the second embodiment is 90 degrees. [Figure 8] FIG. 8 is a graph showing the directivity pattern when the phase difference of the array antenna according to the second embodiment is 180 degrees. [Figure 9] FIG. 9 is a graph showing the directional characteristics of the array antenna according to the second embodiment when there is no phase difference. [Figure 10]FIG. 10 is a graph showing the directional characteristics of the array antenna according to the second embodiment when there is no phase difference with a cable connected. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An antenna according to one embodiment of the present disclosure comprises a loop-shaped antenna element formed by a conductor having open ends at both ends, and a ring-shaped first ground conductor connected to one of the open ends of the antenna element and arranged in a closed manner so as to surround the outer periphery of the antenna element.

[0010] For example, one open end of the antenna element may be connected to a ground conductor (called a second ground conductor) of a control board equipped with a control circuit for controlling the antenna, and a ground conductor (for example, an outer conductor of a coaxial cable) of a cable such as a coaxial cable may be connected to the second ground conductor, and power may be supplied to the antenna element via the cable. In such a case, current may leak from the antenna element to the second ground conductor, and the leaked current may flow to the ground conductor of the cable, and the radiation characteristics of the antenna may be affected by the cable. Therefore, a ring-shaped first ground conductor arranged to surround the outer periphery of the antenna element is connected to one open end of the antenna element. This makes it difficult for current to leak from the antenna element to the second ground conductor, and makes it difficult for current to flow to the ground conductor of the cable connected to the second ground conductor. Therefore, the radiation characteristics of the antenna are less likely to be affected by the cable, and the radiation characteristics can be improved.

[0011] The antenna element may be formed in a circular loop shape.

[0012] In this manner, the antenna element may be formed in a circular loop.

[0013] The antenna may further include a perturbation element formed of a conductor branched off from the antenna element.

[0014] According to this, the perturbation element allows the antenna to radiate circularly polarized radio waves.

[0015] An antenna system according to one embodiment of the present disclosure comprises the above-mentioned antenna and a control board, the control board comprising a control circuit for controlling the antenna and a second ground conductor connected to one open end of the antenna element and the first ground conductor.

[0016] This makes it possible to provide an antenna system capable of improving radiation characteristics.

[0017] An array antenna according to one aspect of the present disclosure is constructed by arranging a plurality of the above-described antennas.

[0018] This makes it possible to provide an array antenna capable of improving radiation characteristics.

[0019] An array antenna system according to one embodiment of the present disclosure comprises the above-mentioned array antenna and a control board, wherein the control board comprises a control circuit for controlling the array antenna, the control circuit including a phase control unit for controlling the phase of radio waves output from the multiple antennas that constitute the array antenna, and a second ground conductor connected to one open end of the antenna element and the first ground conductor.

[0020] This makes it possible to provide an array antenna system capable of improving radiation characteristics.

[0021] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure.

[0022] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to FIG. 1 to FIG. 2B.

[0023] FIG. 1 is a plan view of an antenna system 1 according to the first embodiment.

[0024] The antenna system 1 is a system for emitting and receiving radio waves. The antenna system 1 includes an antenna 10 and a control board 20. The antenna 10 and the control board 20 may be integrally formed. For example, as shown in FIG. 1, the antenna system 1 may be realized by a single board 30. The board 30 may be, for example, a printed wiring board, and the antenna 10 and the control board 20 may be formed on the single board 30. In FIG. 1, the left side of the board 30 is called the antenna 10, and the right side is called the control board 20. The antenna 10 and the control board 20 do not have to be formed on the single board 30, and may be formed separately.

[0025] The antenna 10 comprises an antenna element 11, a first ground conductor 12, a perturbation element 13, and a feed point 14.

[0026] The antenna element 11 is a loop-shaped radiating element formed by a conductor having open ends at both ends. The antenna element 11 is formed, for example, as a conductor pattern on a substrate 30. In FIG. 1, the antenna element 11 is hatched with diagonal lines extending from the upper right to the lower left in order to make the shape of the antenna element 11 easier to understand. The antenna element 11 is formed, for example, in a circular loop shape. Note that the antenna element 11 is not limited to a circular shape, and may be a polygonal shape as long as it is loop-shaped. In addition, FIG. 1 shows the antenna element 11 in a loop shape of one turn as the loop-shaped antenna element 11, but the antenna element 11 is not limited to a loop shape of one turn, and may be a loop shape of one turn or more (i.e., a spiral shape). One open end of the antenna element 11 is connected to the first ground conductor 12 and the second ground conductor 21 described later. The other open end side of the antenna element 11 is connected to a feeding point 14.

[0027] The first ground conductor 12 is a ring-shaped ground conductor that is connected to one open end of the antenna element 11 and is arranged so as to be closed so as to surround the outer periphery of the antenna element 11. The first ground conductor 12 is formed, for example, as a conductor pattern on the substrate 30. In FIG. 1, the first ground conductor 12 is hatched with dots to make the shape of the first ground conductor 12 easier to understand. In addition, a dashed line is added to the boundary between the first ground conductor 12 and a second ground conductor 21 described later to make it easier to understand that the first ground conductor 12 is ring-shaped. For example, the first ground conductor 12 and the second ground conductor 21 described later may be connected without a break on the substrate 30. For example, the first ground conductor 12 is arranged along the antenna element 11. For example, since the antenna element 11 is formed in a circular loop shape, the first ground conductor 12 is formed in a ring shape so as to follow the outer periphery of the loop. The first ground conductor 12 does not have to be formed in a circular ring shape, and may be formed in a polygonal ring shape, as long as it is arranged in a closed manner so as to surround the outer periphery of the antenna element 11. For example, when the antenna element 11 is in a square loop shape, the first ground conductor 12 may also be formed in a square ring shape along the outer periphery of the antenna element 11.

[0028] The perturbation element 13 is a radiating element composed of a conductor branched from the antenna element 11. The perturbation element 13 is formed, for example, as a conductor pattern on the substrate 30. In FIG. 1, in order to make the shape of the perturbation element 13 easier to understand, the perturbation element 13 is hatched with diagonal lines extending from the upper left to the lower right. The perturbation element 13 is formed so as to branch from the loop-shaped antenna element 11 and extend inside the loop, but may be formed so as to extend outside the loop. The perturbation element 13 has a linear shape, but may also be curved. The perturbation element 13 allows the antenna 10 to radiate circularly polarized radio waves. For example, right-handed circularly polarized radio waves can be radiated toward the front side of the paper in FIG. 1, and left-handed circularly polarized radio waves can be radiated toward the back side of the paper in FIG. The antenna 10 does not need to include the perturbation element 13 when radiating linearly polarized radio waves.

[0029] Feeding point 14 is provided, for example, on the other open end side of antenna element 11, and is a point for feeding high frequency power to antenna element 11 and transmitting high frequency power generated by receiving radio waves at antenna element 11 to a receiver or the like. For example, feeding point 14 is connected to an input / output IF (interface) 23 to which a cable such as a coaxial cable is connected via control circuit 22, as described below. Note that, although feeding point 14 is shown to be provided at the other open end of antenna element 11 in FIG. 1, it does not have to be provided at that open end, and may be provided at a position offset from that open end of antenna element 11.

[0030] The control board 20 includes a second ground conductor 21, a control circuit 22, and an input / output IF 23.

[0031] The second ground conductor 21 is a ground conductor connected to one open end of the antenna element 11 and the first ground conductor 12. The second ground conductor 21 is formed, for example, as a solid pattern on the control board 20 (board 30). In Fig. 1, the second ground conductor 21 is hatched with dots different from those of the first ground conductor 12 in order to make the shape of the second ground conductor 21 easier to understand.

[0032] The control circuit 22 is a circuit that controls the antenna 10. The components of the control circuit 22 may be provided only on one main surface of the control board 20, or on both main surfaces, or, when the control board 20 (board 30) is a multi-layer board, may be provided on an inner layer. The control circuit 22 includes, for example, an impedance matching circuit, a filter circuit, or a switch circuit.

[0033] The input / output IF23 is an interface to which a cable such as a coaxial cable is connected, and when the cable is a coaxial cable, it is a coaxial connector. The input / output IF23 is connected to, for example, an RFIC (Radio Frequency Integrated Circuit) or the like via the cable. For example, when the cable is a coaxial cable and the input / output IF23 is a coaxial connector, the coaxial cable is connected to the coaxial connector, and the inner conductor of the coaxial cable is connected to the power feed point 14 via the control circuit 22. This allows high-frequency power from the RFIC or the like to be supplied to the antenna element 11 during transmission, and also allows high-frequency power from the antenna element 11 to be transmitted to the RFIC or the like during reception. In addition, the outer conductor (ground conductor) of the coaxial cable is connected to the second ground conductor 21.

[0034] A characteristic feature of the present disclosure is a ring-shaped first ground conductor 12 that is connected to one open end of the antenna element 11 and is arranged in a closed manner so as to surround the outer periphery of the antenna element 11. The effect of the antenna 10 having such a first ground conductor 12 will be described with reference to Figures 2A and 2B.

[0035] Fig. 2A is a diagram showing a simulation result of current distribution in an antenna system according to a comparative example. Fig. 2B is a diagram showing a simulation result of current distribution in the antenna system 1 according to embodiment 1. In Fig. 2A and Fig. 2B, the lighter the color, the more concentrated the current is.

[0036] The antenna system according to the comparative example does not include the first ground conductor 12. Therefore, by comparing Fig. 2A with Fig. 2B, the effect of providing the first ground conductor 12 can be confirmed.

[0037] 2A, when the first ground conductor 12 is not provided, current is concentrated in the portion of the second ground conductor 21 surrounded by the dashed line A, and it can be seen that a large amount of current flows from the antenna element 11 to the second ground conductor 21. For example, when the ground conductor of a cable is connected to the second ground conductor 21, the current leaking from the antenna element 11 to the second ground conductor 21 flows into the ground conductor of the cable. This may result in the radiation characteristics of the antenna 10 being affected by the cable (e.g., radiation noise from the cable) and degrading the radiation characteristics.

[0038] 2B, in the case of the antenna system 1 including the first ground conductor 12, the current does not concentrate in the portion surrounded by the dashed line A in the second ground conductor 21, but instead, the current concentrates in the portion surrounded by the dashed line B in the first ground conductor 12. In other words, by providing the first ground conductor 12, the flow of the current from the antenna element 11 to the second ground conductor 21 can be suppressed.

[0039] As described above, one open end of the antenna element 11 may be connected to the second ground conductor 21 of the control board 20, and a ground conductor of a cable such as a coaxial cable (for example, an outer conductor of the coaxial cable) may be connected to the second ground conductor 21, and power may be supplied to the antenna element 11 via the cable. In such a case, a current may leak from the antenna element 11 to the second ground conductor 21, and the leaked current may flow to the ground conductor of the cable, and the radiation characteristics of the antenna 10 may be affected by the cable. Therefore, a ring-shaped first ground conductor 12 arranged to surround the outer periphery of the antenna element 11 is connected to one open end of the antenna element 11. This makes it difficult for a current to leak from the antenna element 11 to the second ground conductor 21, and makes it difficult for a current to flow to the ground conductor of the cable connected to the second ground conductor 21. Therefore, the radiation characteristics of the antenna 10 are less likely to be affected by the cable, and the radiation characteristics can be improved.

[0040] (Embodiment 2) Next, a second embodiment will be described with reference to Fig. 3 to Fig. 10. In the second embodiment, an array antenna 100 configured by arranging a plurality of antennas 10 according to the first embodiment and an array antenna system 2 including the array antenna 100 will be described.

[0041] FIG. 3 is a plan view of an array antenna system 2 according to the second embodiment.

[0042] The array antenna system 2 is a system for emitting and receiving radio waves. The array antenna system 2 includes an array antenna 100 and a control board 200. In the array antenna system 2, the directivity of the array antenna 100 can be controlled. That is, radio waves can be transmitted to and received from an object disposed in a specific direction relative to the array antenna 100. The array antenna 100 and the control board 200 may be integrally formed. For example, as shown in FIG. 3, the array antenna system 2 may be realized by one board 300. The board 300 may be, for example, a printed wiring board, and the array antenna 100 and the control board 200 may be formed on one board 300. In FIG. 3, the lower part of the board 300 is called the array antenna 100, and the upper part is called the control board 200. The array antenna 100 and the control board 200 do not have to be formed on one board 300, and may be formed separately.

[0043] The array antenna 100 is configured by arranging a plurality of antennas 10 according to the first embodiment, and includes, for example, four antennas 10. Here, the four antennas 10 are antennas 10a to 10d. That is, each of the antennas 10a to 10d includes an antenna element 11, a first ground conductor 12, a perturbation element 13, and a feed point 14. The antenna element 11, the first ground conductor 12, and the perturbation element 13 of each of the antennas 10a to 10d are formed, for example, as a conductor pattern on a substrate 300. The feed point 14 of each of the antennas 10a to 10d is connected to an input / output IF 230 to which a cable such as a coaxial cable is connected via a control circuit 220, as described later. The number of antennas 10 included in the array antenna 100 is not limited to four, and may be two, three, five or more.

[0044] The control board 200 includes a second ground conductor 210, a control circuit 220, and an input / output IF230.

[0045] The second ground conductor 210 is a ground conductor connected to one open end of each of the antenna elements 11 of the antennas 10a to 10d and to each of the first ground conductors 12 of the antennas 10a to 10d. The second ground conductor 210 is formed, for example, as a solid pattern on the control board 200 (board 300). In Fig. 3, the second ground conductor 210 is hatched with dots different from those of the first ground conductor 12 in order to make the shape of the second ground conductor 210 easier to understand.

[0046] The control circuit 220 is a circuit that controls the array antenna 100. The components of the control circuit 220 may be provided only on one main surface of the control board 200, or may be provided on both main surfaces. When the control board 200 (board 300) is a multi-layer board, the components may be provided on an inner layer. The control circuit 220 includes, for example, an impedance matching circuit, a filter circuit, or a switch circuit. In addition, for example, the control circuit 220 includes a phase control unit 227 (see FIG. 4 described later) that controls the phase of radio waves output from the multiple antennas 10a to 10d that constitute the array antenna 100.

[0047] The input / output IF 230 is an interface to which a cable such as a coaxial cable is connected, and when the cable is a coaxial cable, it is a coaxial connector. The input / output IF 230 is connected to, for example, an RFIC or the like via a cable. For example, when the cable is a coaxial cable and the input / output IF 230 is a coaxial connector, the coaxial cable is connected to the coaxial connector, and the inner conductor of the coaxial cable is connected to each of the feeding points 14 of the antennas 10a to 10d via the control circuit 220. This allows high-frequency power from the RFIC or the like to be supplied to each of the antenna elements 11 of the antennas 10a to 10d during transmission, and also allows high-frequency power from each of the antenna elements 11 of the antennas 10a to 10d to be transmitted to the RFIC or the like during reception. In addition, the outer conductor (ground conductor) of the coaxial cable is connected to the second ground conductor 210.

[0048] Here, phase control section 227 will be described with reference to FIG. 4 to FIG.

[0049] Fig. 4 is a circuit diagram showing an example of phase control section 227 according to the second embodiment. In addition to phase control section 227, Fig. 4 also shows input / output IF 230 and antennas 10a to 10d. Input / output IF 230 in Fig. 4 shows, for example, a terminal to which an inner conductor of a coaxial cable is connected. A portion of input / output IF 230 to which an outer conductor (ground conductor) of the coaxial cable is connected is connected to second ground conductor 210 (not shown in Fig. 4). Control circuit 220 may include other circuits such as an impedance matching circuit or a filter circuit in addition to phase control section 227, but the other circuits are not shown in Fig. 4.

[0050] For example, by imparting a phase difference to the high frequency signals transmitted to each of the antennas 10a to 10d via the input / output IF 230, the directivity of the array antenna 100 can be controlled.

[0051] Phase control unit 227 is configured to control the directivity of array antenna 100, and includes switches SW11, SW12 and phase shifters α1 to αn (n is an integer equal to or greater than 2) provided corresponding to antenna 10a, switches SW21, SW22 and phase shifters β1 to βn provided corresponding to antenna 10b, switches SW31, SW32 and phase shifters γ1 to γn provided corresponding to antenna 10c, and switches SW41, SW42 and phase shifters δ1 to δn provided corresponding to antenna 10d.

[0052] The switch SW11 is an SPnT (Single Pole n Throw) switch, with a common terminal connected to the input / output IF 230 and a selection terminal connected to the phase shifters α1 to αn. The switch SW21 is an SPnT switch, with a common terminal connected to the input / output IF 230 and a selection terminal connected to the phase shifters β1 to βn. The switch SW31 is an SPnT switch, with a common terminal connected to the input / output IF 230 and a selection terminal connected to the phase shifters γ1 to γn. The switch SW41 is an SPnT switch, with a common terminal connected to the input / output IF 230 and a selection terminal connected to the phase shifters δ1 to δn.

[0053] The phase shifters α1 to αn, β1 to βn, γ1 to γn, and δ1 to δn are phase adjustment circuits. The phase shifters α1 to αn, β1 to βn, γ1 to γn, and δ1 to δn are circuits made up of impedance elements such as inductors and capacitors, and the amount of phase adjustment is determined by the connection form and element parameters of each impedance element.

[0054] The switch SW12 is an SPnT switch having a common terminal connected to the feed point 14 of the antenna 10a and a selection terminal connected to the phase shifters α1 to αn. The switch SW22 is an SPnT switch having a common terminal connected to the feed point 14 of the antenna 10b and a selection terminal connected to the phase shifters β1 to βn. The switch SW32 is an SPnT switch having a common terminal connected to the feed point 14 of the antenna 10c and a selection terminal connected to the phase shifters γ1 to γn. The switch SW42 is an SPnT switch having a common terminal connected to the feed point 14 of the antenna 10d and a selection terminal connected to the phase shifters δ1 to δn.

[0055] Each switch is controlled according to an instruction from the RFIC or an instruction from an integrated circuit such as a microcomputer included in the control circuit 220. By controlling each switch, it is possible to control which phase shifter the high frequency signal from the input / output IF 230 passes through, that is, it is possible to adjust the phase of the high frequency signal according to the phase shifter through which the signal passes. This makes it possible to shift the phase of the high frequency signal transmitted to each of the antennas 10a to 10d constituting the array antenna, and to control the directivity of the array antenna 100.

[0056] Here, a more detailed configuration example of phase control section 227 will be described with reference to FIG. 5 focusing on switch SW11, phase shifters α1 to αn, and switch SW12.

[0057] Fig. 5 is a circuit configuration diagram showing an example of a part of phase control section 227 according to embodiment 2. In Fig. 5, switches SW11 and SW21 are SP4T switches, and phase shifters α1 to α4 are shown (that is, n=4).

[0058] 5, the phase shifters α1 to α4 are realized by, for example, π-type LC circuits. Note that the numbers and connection forms of the inductors and capacitors are not limited to those shown in FIG.

[0059] For example, when the amount of adjustment of the phase of the high frequency signal transmitted to the antenna 10a is set according to the phase shifter α1, the switches SW11 and SW12 are controlled so that a common terminal of the switches SW11 and SW12 is connected to the uppermost selection terminal among the selection terminals shown in Fig. 5. By adjusting the parameters of the inductors and capacitors constituting each of the phase shifters α1 to α4, for example, phase characteristics as shown in Fig. 6 can be realized.

[0060] 6 is a graph showing an example of phase characteristics of phase shifters α1 to α4 in phase control section 227 according to embodiment 2. Note that the high-frequency signals transmitted to antennas 10a to 10d are, for example, wireless signals in the UHF (Ultra High Frequency) band, and attention is paid to the phases of phase shifters α1 to α4 at 0.92 GHz.

[0061] 6, at 0.92 GHz, the phase shifter α1 can shift the phase of the signal passing through the phase shifter α1 by 38 degrees, the phase shifter α2 can shift the phase of the signal passing through the phase shifter α2 by -9 degrees, the phase shifter α3 can shift the phase of the signal passing through the phase shifter α3 by -103 degrees, and the phase shifter α4 can shift the phase of the signal passing through the phase shifter α4 by -143 degrees. The phase shifters β1 to β4, phase shifters γ1 to γ4, and phase shifters δ1 to δ4 can also shift the phase of the signal passing through them in the same way as the phase shifters α1 to α4.

[0062] Next, the fact that directivity can be controlled by shifting the phase will be explained with reference to Figs.

[0063] FIG. 7 is a graph showing the directivity pattern when the phase difference of the array antenna 100 according to the second embodiment is 90 degrees.

[0064] FIG. 8 is a graph showing the directivity pattern when the phase difference of the array antenna 100 according to the second embodiment is 180 degrees.

[0065] FIG. 9 is a graph showing the directivity characteristics of the array antenna 100 according to the second embodiment when there is no phase difference.

[0066] For example, each switch is controlled so that the phase difference between the high frequency signal transmitted to antenna 10a and the high frequency signal transmitted to antenna 10b is 90 degrees, the phase difference between the high frequency signal transmitted to antenna 10b and the high frequency signal transmitted to antenna 10c is 90 degrees, and the phase difference between the high frequency signal transmitted to antenna 10c and the high frequency signal transmitted to antenna 10d is 90 degrees. This allows the tilt angle of array antenna 100 to be, for example, about 30 degrees, as shown in Fig. 7.

[0067] Also, for example, each switch is controlled so that the phase difference between the high frequency signal transmitted to antenna 10a and the high frequency signal transmitted to antenna 10b is 180 degrees, the phase difference between the high frequency signal transmitted to antenna 10b and the high frequency signal transmitted to antenna 10c is 180 degrees, and the phase difference between the high frequency signal transmitted to antenna 10c and the high frequency signal transmitted to antenna 10d is 180 degrees. This allows the tilt angle of array antenna 100 to be, for example, 60 degrees, as shown in Fig. 8.

[0068] Also, for example, each switch is controlled so that the phase difference between the high frequency signal transmitted to antenna 10a and the high frequency signal transmitted to antenna 10b is 0 degrees, the phase difference between the high frequency signal transmitted to antenna 10b and the high frequency signal transmitted to antenna 10c is 0 degrees, and the phase difference between the high frequency signal transmitted to antenna 10c and the high frequency signal transmitted to antenna 10d is 0 degrees. In this case, as shown in Fig. 9, the tilt angle of array antenna 100 can be set to, for example, 0 degrees (that is, the directivity can be not controlled).

[0069] In this manner, the phase control section 227 applies a phase difference to the high frequency signals transmitted to the antennas 10a to 10d, respectively, so that the directivity of the array antenna 100 can be controlled.

[0070] 7 to 9 show the directional characteristics of the array antenna 100 when no cable is connected. Therefore, the effect on the directional characteristics when a cable is connected will be described with reference to FIG. 10, focusing on the array antenna 100 when there is no phase difference (i.e., in the state shown in FIG. 9).

[0071] FIG. 10 is a graph showing the directivity characteristics of array antenna 100 according to the second embodiment when there is no phase difference with a cable connected.

[0072] The gain of the array antenna 100 when there is no phase difference is 6.33 dBi when the cable is not connected as shown in Figure 9, whereas it is 5.08 dBi when the cable is connected as shown in Figure 10, so the gain is somewhat smaller when the cable is connected. However, this difference in gain includes about 1 dB of loss due to the cable itself and the loss in the feed line, so the actual gain difference is about 0.3 dB. Therefore, it can be seen that there is almost no effect of the cable other than the loss of the cable itself and the loss of the feed line, for example, the effect of noise radiation from the cable.

[0073] This is because, as described in the first embodiment, one open end of each of the antenna elements 11 of the antennas 10a to 10d is connected to the ring-shaped first ground conductor 12 arranged so as to surround the outer periphery of the antenna element 11. In other words, current is less likely to leak from each of the antenna elements 11 of the antennas 10a to 10d to the second ground conductor 210, and current is less likely to flow in the ground conductor of the cable connected to the second ground conductor 210. Therefore, the radiation characteristics of the array antenna 100 are less likely to be affected by the cable, and the radiation characteristics can be improved as shown in FIG.

[0074] The antenna 10, the antenna system 1, the array antenna 100, and the array antenna system 2 according to one or more aspects have been described based on the embodiments, but the present disclosure is not limited to the above-mentioned embodiments. As long as it does not deviate from the spirit of the present disclosure, various modifications conceivable by a person skilled in the art to the above-mentioned embodiments and forms constructed by combining components in different embodiments may also be included within the scope of one or more aspects. [Industrial Applicability]

[0075] The present disclosure can be used in devices or systems equipped with antennas. [Explanation of symbols]

[0076] 1 Antenna System 2 Array Antenna System 10, 10a, 10b, 10c, 10d Antennas 11 Antenna elements 12 First ground conductor 13 Perturbation elements 14 Power supply point 20, 200 Control board 21, 210 Second ground conductor 22, 220 control circuit 23, 230 Input / Output IF 30, 300 boards 100 Array Antenna 227 Phase Control Section SW11, SW12, SW21, SW22, SW31, SW32, SW41, SW42 switches α1, α2, α3, α4, αn, β1, β2, βn, γ1, γ2, γn, δ1, δ2, δn Phaser

Claims

1. a loop-shaped antenna element formed by a conductor having open ends at both ends; an antenna including a first ground conductor having a ring shape connected to the one open end of the antenna element and arranged to close and surround an outer periphery of the antenna element; A control board; The control board includes: A control circuit for controlling the antenna; a second ground conductor connected to the one open end of the antenna element and the first ground conductor, the second ground conductor is formed as a solid pattern on the control board, The first ground conductor and the second ground conductor are connected seamlessly to each other.

2. The antenna system of claim 1 , wherein the antenna element is formed in a circular loop.

3. 3. The antenna system according to claim 1, further comprising a perturbation element formed by a conductor branched from the antenna element.

4. A loop-shaped antenna element formed by a conductor having open ends at both ends; an array antenna including a plurality of antennas arranged in a row, each antenna including a first ground conductor connected to one of the open ends of the antenna element and arranged to close and surround an outer periphery of the antenna element; A control board; The control board includes: A control circuit for controlling the array antenna, the control circuit including a phase control unit for controlling phases of radio waves output from the plurality of antennas constituting the array antenna; a second ground conductor connected to the one open end of the antenna element and the first ground conductor, the second ground conductor is formed as a solid pattern on the control board, An array antenna system, wherein the first ground conductor and the second ground conductor are connected without interruption.

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