Array antenna device

Abstract

To provide an array antenna device that can be reduced in size while suppressing a decrease in antenna efficiency.SOLUTION: An array antenna device 1 includes a substrate having a regular polygonal shape and a pair of antenna conductors 111-1 to 111-6, one for each side, that constitute a dipole antenna. Each antenna conductor includes a first component 111a, a second component 111b, and a third component 111c. The first component extends along the side, has one end near the center of the side, and has the other end located farther from the center of the side than the first end. The second component extends along a straight line perpendicular to the side, and has one end connected to one end of the first component. The third component extends along a straight line intersecting the side, and has one end connected to the other end of the first component, and has the other end located farther from the side than the first end.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an array antenna device. [Background technology]

[0002] Array antenna devices equipped with multiple antennas are known. One such array antenna device is described in Patent Document 1, which includes stacked conductor layers and insulating layers, and the conductor layers include multiple antenna conductors that respectively configure the multiple antennas. The multiple antennas are arranged radially. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-32937 Summary of the Invention [Problem to be solved by the invention]

[0004] A dipole antenna formed by a pair of antenna conductors has antenna characteristics that are unlikely to change even when the size of the antenna device is relatively small compared to the size of the antenna. The pair of antenna conductors that make up the dipole antenna are axisymmetric with respect to a reference line. Each of the pair of antenna conductors that make up the dipole antenna is L-shaped and includes a first component portion that extends along a line perpendicular to the reference line and a second component portion that extends along the reference line. Therefore, it is conceivable to arrange a dipole antenna as the antenna of the array antenna device so that the first component portion extends along the sides that form a regular polygon.

[0005] The overall length of the antenna conductor is determined according to the wavelength of the electromagnetic waves, which are wireless signals. On the other hand, the longer the length of the second component, the lower the antenna efficiency. Antenna efficiency is either radiation efficiency or reception efficiency. Radiation efficiency represents the ratio of the power of the electromagnetic waves radiated from the antenna into space to the power input to the antenna. Reception efficiency represents the ratio of the power output from the antenna to the power of the electromagnetic waves received from space by the antenna. For this reason, it is possible to shorten the length of the second component and lengthen the length of the first component.

[0006] However, as the length of the first component section increases, the sides of the regular polygon become longer, resulting in a larger size of the array antenna device. Thus, when a dipole antenna is used in the array antenna device, there is a problem in that it is not possible to reduce the size while suppressing a decrease in antenna efficiency.

[0007] One of the objects of the present invention is to reduce the size while suppressing a decrease in antenna efficiency. [Means for solving the problem]

[0008] In one aspect, the array antenna device includes a first conductor layer and a first insulator layer that are stacked. The first insulator layer includes a substrate having a regular polygonal shape formed by N sides (N is an integer of 3 or more). The first conductor layer includes, for each of the N sides, a pair of antenna conductors that constitute a dipole antenna associated with that side. A pair of antenna conductors associated with a side are symmetrical with respect to a line that passes through the center of the side and is perpendicular to the side. Each of the pair of antenna conductors associated with the sides includes a first component portion, a second component portion, and a third component portion. The first component portion extends along the side, has one end near the center of the side, and has the other end at a position farther from the center of the side than the one end. The second component extends along a straight line perpendicular to the side, has one end connected to one end of the first component, and has the other end at a position farther from the side than the one end. The third component portion extends along a straight line intersecting the side, has one end connected to the other end of the first component portion, and has the other end at a position farther from the side than the one end. [Effects of the Invention]

[0009] The size can be reduced while suppressing a decrease in antenna efficiency. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view of an array antenna device according to a first embodiment. [Figure 2] FIG. 2 is a front view of the array antenna device of the first embodiment. [Figure 3] FIG. 2 is a side view of the array antenna device of the first embodiment. [Figure 4] 1 is a cross-sectional view of an array antenna device according to a first embodiment. [Figure 5] 1 is a cross-sectional view of an array antenna device according to a first embodiment. [Figure 6] 1 is a cross-sectional view of an array antenna device according to a first embodiment. [Figure 7] 1 is a cross-sectional view of an array antenna device according to a first embodiment. [Figure 8] FIG. 2 is a rear view of the array antenna device of the first embodiment. [Figure 9] FIG. 2 is a front view of the array antenna device of the first embodiment, in which hidden lines are represented by dashed lines. [Figure 10] FIG. 10 is a front view of the array antenna device of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the array antenna device of the present invention will be described with reference to FIGS.

[0012] First Embodiment (overview) The array antenna device of the first embodiment includes a first conductor layer and a first insulator layer that are stacked. The first insulator layer includes a substrate having a regular polygonal shape formed by N sides (N is an integer of 3 or more). The first conductor layer includes, for each of the N sides, a pair of antenna conductors that constitute a dipole antenna associated with that side. A pair of antenna conductors associated with a side are symmetrical with respect to a line that passes through the center of the side and is perpendicular to the side. Each of the pair of antenna conductors associated with the sides includes a first component portion, a second component portion, and a third component portion. The first component portion extends along the side, has one end near the center of the side, and has the other end at a position farther from the center of the side than the one end. The second component extends along a straight line perpendicular to the side, has one end connected to one end of the first component, and has the other end at a position farther from the side than the one end. The third component portion extends along a straight line intersecting the side, has one end connected to the other end of the first component portion, and has the other end at a position farther from the side than the one end.

[0013] This allows the length of the first component to be shortened while maintaining the overall length of the antenna conductor, compared to when the antenna conductor is composed of a first component and a second component. This allows the length of the sides of the substrate to be shortened. As a result, the size of the array antenna device can be reduced while suppressing a decrease in antenna efficiency. Next, the array antenna device of the first embodiment will be described in more detail.

[0014] (composition) The array antenna device 1 of the first embodiment will be described below using a right-handed Cartesian coordinate system having x-, y-, and z-axes as shown in Figures 1 to 9. Note that in this specification, a similar coordinate system is also used in Figure 10, which will be described later.

[0015] In this example, viewing the array antenna device 1 in the negative direction of the z axis is referred to as viewing the array antenna device 1 from the front. In this example, the positive direction of the z axis and the negative direction of the z axis correspond to the vertically upward and downward directions, respectively. Note that the z axis direction does not have to correspond to the vertical direction.

[0016] Fig. 1 is a perspective view of the array antenna device 1. Fig. 2 is a front view of the array antenna device 1. Fig. 3 is a side view of the array antenna device 1. Fig. 4 is a cross-sectional view of the array antenna device 1 taken along the plane indicated by line IV-IV in Fig. 2.

[0017] Fig. 5 is a cross-sectional view of the array antenna device 1 taken along a plane indicated by line VV in Fig. 3. Fig. 6 is a cross-sectional view of the array antenna device 1 taken along a plane indicated by line VI-VI in Fig. 3. Fig. 7 is a cross-sectional view of the array antenna device 1 taken along a plane indicated by line VII-VII in Fig. 3. Fig. 8 is a rear view of the array antenna device 1. Fig. 9 is a front view of the array antenna device 1 in which hidden lines are represented by dashed lines.

[0018] In this example, the array antenna device 1 communicates radio signals that are electromagnetic waves having frequencies between 2400 MHz and 2500 MHz. Note that the array antenna device 1 may also communicate radio signals that are electromagnetic waves having frequencies other than 2400 MHz to 2500 MHz.

[0019] In this example, the array antenna device 1 is used to estimate the direction from which a received radio signal arrives. Note that the array antenna device 1 may also be used to transmit a radio signal with high strength in a specific direction (in other words, a radio signal with directionality).

[0020] As shown in Figure 3, the array antenna device 1 comprises a first conductor layer 11, a first insulator layer 21, a second conductor layer 12, a second insulator layer 22, a third conductor layer 13, a third insulator layer 23, and a fourth conductor layer 14.

[0021] The first conductor layer 11, the first insulator layer 21, the second conductor layer 12, the second insulator layer 22, the third conductor layer 13, the third insulator layer 23, and the fourth conductor layer 14 are stacked in this order. 5 to 7, each of the first insulator layer 21, the second insulator layer 22, and the third insulator layer 23 includes a flat substrate having a regular polygonal shape (in other words, a regular N-sided polygonal shape) formed by N sides SD-1 to SD-N. N represents an integer of 3 or greater. In this example, N represents 6.

[0022] In this example, the substrate is a glass epoxy substrate. However, the substrate may be a substrate other than a glass epoxy substrate (for example, a paper phenol substrate, a paper epoxy substrate, a glass composite substrate, a Teflon ("Teflon" is a registered trademark) substrate, a flexible substrate, etc.).

[0023] In this example, the first insulator layer 21 has a thickness of 0.5 mm to 2.0 mm. In this example, the second insulator layer 22 and the third insulator layer 23 are thinner than the first insulator layer 21. In this example, the second insulator layer 22 and the third insulator layer 23 have a thickness of 0.1 mm to 0.4 mm. The second insulator layer 22 and the third insulator layer 23 may have the same thickness as the first insulator layer 21, or may be thicker than the first insulator layer 21.

[0024] 2, the first conductor layer 11 includes N pairs of antenna conductors 111-1 to 111-N, N pairs of balun conductors 112-1 to 112-N, and a grounding conductor 113. In this example, the conductor constituting the first conductor layer 11 is copper foil. Note that the conductor constituting the first conductor layer 11 may be a metal foil other than copper foil.

[0025] The N pairs of antenna conductors 111-1 to 111-N correspond to the N sides SD-1 to SD-N, respectively. Each of the N pairs of antenna conductors 111-1 to 111-N constitutes a dipole antenna.

[0026] In this example, the pair of antenna conductors 111-m have a shape and position obtained by rotating the pair of antenna conductors 111-1 by 360(m-1) / N degrees clockwise when viewed from the front of the array antenna device 1 with respect to the center of the substrate that constitutes the first insulator layer 21. m represents an integer from 2 to N.

[0027] In this example, a pair of antenna conductors 111-n associated with side SD-n are symmetrical with respect to a line that passes through the center of side SD-n and is perpendicular to side SD-n, where n represents an integer from 1 to N.

[0028] Each of the pair of antenna conductors 111-n includes a first component portion 111a, a second component portion 111b, and a third component portion 111c.

[0029] The first component 111a extends along the side SD-n, has one end near the center of the side SD-n, and has the other end at a position farther from the center of the side SD-n than the one end. For example, of the pair of antenna conductors 111-1, one end of the first component 111a of the antenna conductor 111-1 on the negative side of the x-axis is the end of the first component 111a in the positive direction of the x-axis, and the other end of the first component 111a is the end of the first component 111a in the negative direction of the x-axis.

[0030] The second component 111b extends along a straight line perpendicular to the side SD-n, has one end connected to one end of the first component 111a, and has the other end at a position farther from the side SD-n than the first end. For example, of the pair of antenna conductors 111-1, one end of the second component 111b of the antenna conductor 111-1 on the negative side of the x-axis is the end of the second component 111b in the positive direction of the y-axis, and the other end of the second component 111b is the end of the second component 111b in the negative direction of the y-axis.

[0031] The third component 111c extends along a straight line intersecting with the side SD-n, has one end connected to the other end of the first component 111a, and has the other end at a position farther from the side SD-n than the one end. For example, of the pair of antenna conductors 111-1, one end of the third component 111c of the antenna conductor 111-1 on the negative side of the x-axis is the end of the third component 111c in the positive direction of the y-axis, and the other end of the third component 111c is the end of the third component 111c in the negative direction of the y-axis.

[0032] In this example, the base angle of an isosceles triangle having side SD-n as the base and the center of the substrate constituting the first insulator layer 21 as the vertex is 60 degrees. Also, in this example, the angle formed by the first component 111a and the third component 111c is 90 degrees. Therefore, in this example, the angle formed by the equal side of the isosceles triangle and the third component 111c is 30 degrees. Note that, in this example, the angle formed by the equal side of the isosceles triangle and the third component 111c may be any angle less than 60 degrees.

[0033] In other words, in this example, each of the pair of antenna conductors 111-n has an isosceles triangle whose base is side SD-n and whose vertex is the center of the substrate constituting the first insulator layer 21, and the angle formed by the equal side of the isosceles triangle and the third component part 111c is smaller than the base angle of the isosceles triangle.

[0034] N pairs of balun conductors 112-1 to 112-N correspond to N sides SD-1 to SD-N, respectively. Each of the N pairs of balun conductors 112-1 to 112-N constitutes a balun (in other words, a balanced-to-unbalanced transformer).

[0035] In this example, the pair of balun conductors 112-m have a shape and position that are obtained by rotating the pair of balun conductors 112-1 by 360(m-1) / N degrees clockwise when viewed from the front of the array antenna device 1 with respect to the center of the substrate that constitutes the first insulator layer 21.

[0036] A pair of balun conductors 112-n corresponding to side SD-n each have one end connected to the other end of the second component portion 111b of a pair of antenna conductors 111-n corresponding to side SD-n, and each have the other end at a position closer to the center of the substrate constituting the first insulator layer 21 than the one end.

[0037] The ends of the pair of balun conductors 112-n, including the other end, are connected to each other and extend along a straight line that passes through the center of side SD-n and is perpendicular to side SD-n. For example, one end of each of the pair of balun conductors 112-1 is the end of the balun conductor 112-1 in the positive direction of the y-axis, and the other end of each of the pair of balun conductors 112-1 is the end of the balun conductor 112-1 in the negative direction of the y-axis, the end that passes through the center of side SD-1 and extends along a straight line that is perpendicular to side SD-1.

[0038] 2, the grounding conductor 113 is planar and extends in a region having an outer edge closer to the center of the substrate constituting the first insulator layer 21 than the other ends of the N pairs of balun conductors 112-1 to 112-N. In other words, the grounding conductor 113 has an outer edge spaced a predetermined first distance from the other ends of the N pairs of balun conductors 112-1 to 112-N.

[0039] In this example, the ground conductor 113 has a regular polygonal shape formed by N sides SD-1 to SD-N and N sides spaced apart from each other by a predetermined second distance. In this example, the ground conductor 113 corresponds to the second ground conductor.

[0040] 6 and 9, the second conductor layer 12 includes a grounding conductor 121. In this example, the conductor constituting the second conductor layer 12 is copper foil. Note that the conductor constituting the second conductor layer 12 may be a metal foil other than copper foil.

[0041] The grounding conductor 121 has no conductor in an area overlapping with the N pairs of antenna conductors 111-1 to 111-N when viewed from the front of the array antenna device 1, and is planar and extends in an area overlapping with the N pairs of balun conductors 112-1 to 112-N when viewed from the front of the array antenna device 1. In this example, the grounding conductor 121 has a regular polygonal shape formed by N sides SD-1 to SD-N and N sides spaced apart from each other by a predetermined third distance. In this example, the grounding conductor 121 corresponds to the first grounding conductor.

[0042] 8 and 9, the fourth conductor layer 14 includes a grounding conductor 141. In this example, the conductor constituting the fourth conductor layer 14 is copper foil. Note that the conductor constituting the fourth conductor layer 14 may be a metal foil other than copper foil.

[0043] The grounding conductor 141 has no conductor in the region overlapping with the N pairs of antenna conductors 111-1 to 111-N in a front view of the array antenna device 1, and is planar and extends in the region overlapping with the N pairs of balun conductors 112-1 to 112-N in a front view of the array antenna device 1. In this example, the grounding conductor 141 has a regular polygonal shape formed by N sides SD-1 to SD-N and N sides spaced apart by a third distance. Therefore, in this example, the grounding conductor 141 has the same shape as the grounding conductor 121.

[0044] 7 and 9, the third conductor layer 13 includes N connecting conductors 131-1 to 131-N. In this example, the conductor constituting the third conductor layer 13 is copper foil. Note that the conductor constituting the third conductor layer 13 may be a metal foil other than copper foil. The N connecting conductors 131-1 to 131-N correspond to the N sides SD-1 to SD-N, respectively.

[0045] The N connecting conductors 131-1 to 131-N extend radially from the center of the substrate that constitutes the third insulator layer 23. The connecting conductor 131-n associated with the side SD-n passes through the center of the side SD-n and extends along a straight line that is perpendicular to the side SD-n.

[0046] As shown in Figures 1 to 4 and 9, the array antenna device 1 includes a communication circuit 31, a switch 32, N first via conductors V1-1 to V1-N, and N second via conductors V2-1 to V2-N.

[0047] The communication circuit 31 performs at least one of transmitting and receiving wireless signals. In this example, the communication circuit 31 performs both transmitting and receiving wireless signals. Note that the communication circuit 31 may perform only one of transmitting and receiving wireless signals.

[0048] In this example, the communication circuit 31 performs communication according to the Bluetooth ("Bluetooth" is a registered trademark) Low Energy (BLE) method. Note that the communication circuit 31 may perform communication according to a communication method other than the BLE method (for example, Bluetooth other than BLE, or ZigBee ("ZIGBEE" is a registered trademark), etc.).

[0049] The communication circuit 31 is fixed to an end surface in the positive direction of the z-axis of the ground conductor 113. In other words, the communication circuit 31 is located within a region overlapping with the ground conductor 113 when the array antenna device 1 is viewed from the front.

[0050] The switch 32 is fixed to the end face of the ground conductor 113 in the positive direction of the z-axis. In other words, the switch 32 is located within a region overlapping with the ground conductor 113 when viewed from the front of the array antenna device 1. In this example, the switch 32 is located in the center of the substrate that constitutes the first insulator layer 21.

[0051] In a front view of the array antenna device 1, the connecting conductor 131-n associated with the side SD-n has an end closer to the center of the substrate constituting the third insulator layer 23 that overlaps with the switch 32. In a front view of the array antenna device 1, the connecting conductor 131-n associated with the side SD-n has an end farther from the center of the substrate constituting the third insulator layer 23 that overlaps with the other ends of the pair of balun conductors 112-n associated with the side SD-n.

[0052] With this configuration, at least a portion of the connecting conductor 131-n is positioned so that the first conductor layer 11 is sandwiched between it and the communication circuit 31, and is located within an area that overlaps with the grounding conductor 113 when viewed from the front of the array antenna device 1.

[0053] The N first via conductors V1-1 to V1-N correspond to the N sides SD-1 to SD-N, respectively. The first via conductor V1-n corresponding to the side SD-n has a columnar shape with its central axis extending in the z-axis direction so as to penetrate the ground conductor 113, the first insulator layer 21, the ground conductor 121, and the second insulator layer 22 in the z-axis direction, at a position overlapping with the end of the connecting conductor 131-n corresponding to the side SD-n that is closer to the center of the substrate constituting the third insulator layer 23 and the switch 32 when viewed from the front of the array antenna device 1.

[0054] With this configuration, the first via conductor V1-n corresponding to the side SD-n connects the end of the connecting conductor 131-n corresponding to the side SD-n that is closer to the center of the substrate constituting the third insulator layer 23 to the switch 32.

[0055] The N second via conductors V2-1 to V2-N are respectively associated with the N sides SD-1 to SD-N. The second via conductor V2-n associated with the side SD-n has a columnar shape with its central axis extending in the z-axis direction so as to penetrate the first insulator layer 21, the grounding conductor 121, and the second insulator layer 22 in the z-axis direction, at a position that overlaps with an end of one of the connecting conductors 131-n associated with the side SD-n that is farther from the center of the substrate constituting the third insulator layer 23 and the other ends of the pair of balun conductors 112-n associated with the side SD-n, when viewed from the front of the array antenna device 1.

[0056] With this configuration, the second via conductor V2-n corresponding to the side SD-n connects the end of the connecting conductor 131-n corresponding to the side SD-n that is farther from the center of the substrate constituting the third insulator layer 23 to the other end of the pair of balun conductors 112-n corresponding to the side SD-n.

[0057] In this way, the first via conductor V1-n, the connecting conductor 131-n, and the second via conductor V2-n associated with the side SD-n connect the pair of antenna conductors 111-n associated with the side SD-n to the switch 32. In this example, the first via conductor V1-n, the connecting conductor 131-n, and the second via conductor V2-n associated with the side SD-n correspond to wiring that connects the pair of antenna conductors 111-n associated with the side SD-n to the switch 32.

[0058] The switch 32 connects any one pair of antenna conductors 111-n of the N pairs of antenna conductors 111-1 to 111-N to the communication circuit 31. The switch 32 can change the pair of antenna conductors 111-n connected to the communication circuit 31 from among the N pairs of antenna conductors 111-1 to 111-N. With this configuration, in this example, the lengths of the wires connecting the communication circuit 31 to each of the N pairs of antenna conductors 111-1 to 111-N are the same.

[0059] The communication circuit 31 performs at least one of transmitting and receiving radio signals via a pair of antenna conductors 111-n connected by a switch 32.

[0060] In this example, the switch 32 sequentially changes the pair of antenna conductors 111-n connected to the communication circuit 31 among the N pairs of antenna conductors 111-1 to 111-N every time a predetermined switching time elapses.

[0061] The communication circuit 31 estimates the direction from which the received radio signal arrives (in other words, the arrival direction) based on the radio signal received by each of the N pairs of antenna conductors 111-1 to 111-N. In this example, the communication circuit 31 estimates the arrival direction according to the method described in Non-Patent Document 1 below. Note that the communication circuit 31 may estimate the arrival direction according to a method other than this method. (Non-Patent Document 1) Takanori Iwamatsu and three others, "A Study on Circular Array Two-Dimensional Position Estimation in BLE," Technical Report of the Institute of Electronics, Information and Communication Engineers, February 22, 2023, Vol. 122, CAS-396 (CS-397), pp. 83-88

[0062] (operation) Next, the operation of the array antenna device 1 will be described. The switch 32 sequentially switches the pair of antenna conductors 111-n connected to the communication circuit 31 among the N pairs of antenna conductors 111-1 to 111-N every time a predetermined switching time elapses. The communication circuit 31 estimates the direction of arrival based on the radio signals received by each of the N pairs of antenna conductors 111-1 to 111-N.

[0063] As described above, the array antenna device 1 of the first embodiment includes the first conductor layer 11 and the first insulator layer 21 that are stacked one on top of the other. The first insulating layer 21 comprises a substrate having a regular polygonal shape formed by N sides (N is an integer of 3 or more). The first conductor layer 11 includes, for each of the N sides SD-1 to SD-N, a pair of antenna conductors 111-n that constitute a dipole antenna associated with the side SD-n. A pair of antenna conductors 111-n associated with the side SD-n are symmetrical with respect to a line that passes through the center of the side SD-n and is perpendicular to the side SD-n.

[0064] Each of the pair of antenna conductors 111-n associated with the side SD-n includes a first component portion 111a, a second component portion 111b, and a third component portion 111c. The first component portion 111a extends along the side SD-n, has one end near the center of the side SD-n, and has the other end at a position farther from the center of the side SD-n than the one end. The second component 111b extends along a straight line perpendicular to the side SD-n, has one end connected to one end of the first component 111a, and has the other end at a position farther from the side SD-n than the one end. The third component 111c extends along a straight line intersecting with the side SD-n, has one end connected to the other end of the first component 111a, and has the other end at a position farther from the side SD-n than the one end.

[0065] This allows the length of the first component 111a to be shortened while maintaining the overall length of the antenna conductor 111-n, compared to when the antenna conductor is composed of a first component portion and a second component portion. This allows the length of the side SD-n of the substrate to be shortened. As a result, the size of the array antenna device 1 can be reduced while suppressing a decrease in antenna efficiency.

[0066] Furthermore, in the array antenna device 1 of the first embodiment, each of the pair of antenna conductors 111-n corresponding to the side SD-n has an angle formed by the equal side of the isosceles triangle and the third component 111c that is smaller than the base angle of the isosceles triangle whose base is the side SD-n and whose vertex is the center of the substrate.

[0067] This allows the length of the first component 111a to be shortened while maintaining the overall length of the antenna conductor 111-n, compared to when the antenna conductor is composed of a first component portion and a second component portion. This allows the length of the side SD-n of the substrate to be shortened. As a result, the size of the array antenna device 1 can be reduced while suppressing a decrease in antenna efficiency.

[0068] Furthermore, in the array antenna device 1 of the first embodiment, the first conductor layer 11 includes, for each of the N sides SD-1 to SD-N, a pair of balun conductors 112-n that constitute a balun associated with the side SD-n. A pair of balun conductors 112-n corresponding to side SD-n each have one end connected to the other end of the second component 111b of a pair of antenna conductors 111-n corresponding to side SD-n, and each have the other end at a position closer to the center of the substrate than the one end.

[0069] This allows the number of parts used to manufacture the array antenna device 1 to be reduced compared to when a balun is configured using electronic parts such as a coil.

[0070] Furthermore, the array antenna device 1 of the first embodiment includes a first conductor layer 11, a first insulator layer 21, and a second conductor layer 12, which are stacked one on top of the other. The second conductor layer 12 has no conductor in the area overlapping with N pairs of antenna conductors 111-1 to 111-N when viewed from the front of the array antenna device 1, and is provided with a planar first grounding conductor 121 extending in the area overlapping with N pairs of balun conductors 112-1 to 112-N when viewed from the front of the array antenna device 1.

[0071] This allows the impedance of the antenna formed by the pair of antenna conductors 111-n to be matched with the impedance of the balun formed by the pair of balun conductors 112-n, thereby improving the antenna efficiency.

[0072] Furthermore, the array antenna device 1 of the first embodiment includes N wirings (in this example, N connecting conductors 131-1 to 131-N, N first via conductors V1-1 to V1-N, and N second via conductors V2-1 to V2-N), a switch 32, and a communication circuit 31.

[0073] The N wires connect the N pairs of antenna conductors 111-1 to 111-N to the switch 32, respectively. The switch 32 connects a pair of antenna conductors 111-n to the communication circuit 31, and can change the pair of antenna conductors 111-n connected to the communication circuit 31 from among N pairs of antenna conductors 111-1 to 111-N.

[0074] The communication circuit 31 performs at least one of transmitting and receiving radio signals via a pair of antenna conductors 111-n connected by a switch 32.

[0075] This allows the number of parts used to manufacture the array antenna device 1 to be reduced compared to when a communication circuit is provided for each antenna.

[0076] Furthermore, in the array antenna device 1 of the first embodiment, the lengths of the wires connecting the communication circuit 31 to each of the N pairs of antenna conductors 111-1 to 111-N are the same.

[0077] This makes it possible to obtain the phase difference between the antennas of the received radio signal with high accuracy, and therefore to estimate, for example, the direction from which the radio signal arrives with high accuracy.

[0078] Furthermore, in the array antenna device 1 of the first embodiment, the first conductor layer 11 is provided with a planar second grounding conductor 113 that extends in an area having an outer edge at a position closer to the center of the substrate than the other ends of the N pairs of balun conductors 112-1 to 112-N.

[0079] The communication circuit 31 is positioned within a region overlapping with the second ground conductor 113 when the array antenna device 1 is viewed from the front. At least some of the N wirings (in this example, N connecting conductors 131-1 to 131-N, N first via conductors V1-1 to V1-N, and N second via conductors V2-1 to V2-N) are positioned so that the first conductor layer 11 is sandwiched between them and the communication circuit 31, and are positioned within an area that overlaps with the second grounding conductor 113 when viewed from the front of the array antenna device 1.

[0080] This makes it possible to suppress noise generated by the communication circuit 31 in signals transmitted through the N wires.

[0081] Second Embodiment Next, an array antenna device of a second embodiment will be described. The array antenna device of the second embodiment differs from the array antenna device of the first embodiment in that the substrate is square-shaped. The following description will focus on the differences. In the description of the second embodiment, components that are assigned the same reference numerals as those used in the first embodiment are the same or substantially similar.

[0082] (composition) As shown in FIG. 10, the array antenna device 1A of the second embodiment has a square shape when viewed from the front of the array antenna device 1A. FIG. 10 is a front view of the array antenna device 1A.

[0083] In this example, the pair of antenna conductors 111-m have a shape and position obtained by rotating the pair of antenna conductors 111-1 by 90(m-1) degrees clockwise when viewed from the front of the array antenna device 1 with respect to the center of the substrate that constitutes the first insulator layer 21. m represents an integer from 2 to 4.

[0084] In this example, the base angle of an isosceles triangle having the side SD-n as the base and the center of the substrate constituting the first insulator layer 21 as the vertex is 45 degrees. Also, in this example, the angle formed by the first component 111a and the third component 111c is 80 degrees. Therefore, in this example, the angle formed by the equal side of the isosceles triangle and the third component 111c is 35 degrees. Note that, in this example, the angle formed by the equal side of the isosceles triangle and the third component 111c may be any angle less than 45 degrees.

[0085] In other words, in this example, each of the pair of antenna conductors 111-n has an isosceles triangle whose base is side SD-n and whose vertex is the center of the substrate constituting the first insulator layer 21, and the angle formed by the equal side of the isosceles triangle and the third component part 111c is smaller than the base angle of the isosceles triangle.

[0086] The array antenna device 1A of the second embodiment can also achieve the same functions and effects as the array antenna device 1 of the first embodiment.

[0087] The present invention is not limited to the above-described embodiment. For example, various modifications that can be understood by those skilled in the art may be made to the above-described embodiment without departing from the spirit of the present invention.

[0088] For example, the array antenna device 1 or the array antenna device 1A may include N coils that form a balun, instead of the N pairs of balun conductors 112-1 to 112-N. Furthermore, for example, the array antenna device 1 or the array antenna device 1A does not have to include the fourth conductor layer 14. [Explanation of symbols]

[0089] 1,1A Array Antenna Device 11 First conductor layer 111-1~111-N Antenna conductors 111a 1st component 111b Second component 111c Third component 112-1~112-N Balun conductors 113 Grounding conductor 12 Second conductor layer 121 Grounding conductor 13 Third conductor layer 131-1~131-N Connecting conductor 14 Fourth conductor layer 141 Grounding conductor 21 First insulating layer 22 Second insulating layer 23 Third insulating layer 31 Communication Circuit 32 Switch SD-1~SD-N area V1-1 to V1-N First via conductor V2-1~V2-N Second via conductor

Claims

1. An array antenna device, a first conductor layer and a first insulator layer stacked together; the first insulator layer includes a substrate having a regular polygonal shape formed by N sides (N is an integer of 3 or more); the first conductor layer includes, for each of the N sides, a pair of antenna conductors constituting a dipole antenna associated with the side; the pair of antenna conductors associated with the side are symmetrical with respect to a line that passes through the center of the side and is perpendicular to the side, Each of the pair of antenna conductors associated with the side is a first component portion extending along the side, having one end near the center of the side and the other end at a position farther from the center of the side than the one end; a second component extending along a straight line perpendicular to the side, having one end connected to the one end of the first component and having the other end at a position farther from the side than the one end; a third component portion extending along a straight line intersecting the side, having one end connected to the other end of the first component portion and having the other end at a position farther from the side than the one end; An array antenna device comprising:

2. 2. The array antenna device according to claim 1, Each of the pair of antenna conductors associated with the side is An array antenna device in which the angle formed by the equal side of the isosceles triangle and the third component is smaller than the base angle of an isosceles triangle whose base is the side and whose vertex is the center of the substrate.

3. 3. The array antenna device according to claim 1, the first conductor layer includes, for each of the N sides, a pair of balun conductors that constitute a balun associated with the side; An array antenna device in which the pair of balun conductors associated with the sides each have one end connected to the other end of the second component of the pair of antenna conductors associated with the sides, and each have the other end at a position closer to the center of the substrate than the one end.

4. 4. The array antenna device according to claim 3, The first conductor layer, the first insulator layer, and the second conductor layer are stacked together, An array antenna device in which the second conductor layer has no conductors in the area overlapping with the N pairs of antenna conductors when viewed from the front of the array antenna device, and is provided with a planar first grounding conductor extending in the area overlapping with the N pairs of balun conductors when viewed from the front of the array antenna device.

5. 3. The array antenna device according to claim 1, The system includes N lines, a switch, and a communication circuit, The N wirings respectively connect the N pairs of antenna conductors to the switches, the switch connects the pair of antenna conductors to the communication circuit, and is capable of changing the pair of antenna conductors connected to the communication circuit among the N pairs of antenna conductors; The array antenna device, wherein the communication circuit performs at least one of transmitting and receiving radio signals via the pair of antenna conductors connected by the switch.

6. 6. The array antenna device according to claim 5, An array antenna device, wherein the lengths of the wiring connecting the communication circuit and each of the N pairs of antenna conductors are the same.

7. 6. The array antenna device according to claim 5, the first conductor layer includes a planar second ground conductor extending in a region having an outer edge at a position closer to the center of the substrate than the other ends of the N pairs of balun conductors; the communication circuit is positioned within a region overlapping with the second ground conductor in a front view of the array antenna device, An array antenna device in which at least some of the N wirings are positioned so that the first conductor layer is sandwiched between them and the communication circuit, and are positioned within an area that overlaps with the second grounding conductor when viewed from the front of the array antenna device.

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