Antenna equipment

Abstract

To provide an antenna device that can suppress the generation of unwanted radiation. [Solution] The antenna device 10 comprises a substrate 11, a power supply circuit, and a plurality of radiating slots 21. The power supply circuit is provided on the first and second surfaces, which are both surfaces in the thickness direction of the substrate 11. The radiating slots 21 are provided on the first or second surface of the substrate 11 and are electromagnetically coupled to the power supply circuit. The power supply circuit comprises a slot line 22 provided on the same surface as the radiating slots 21 on the first and second surfaces of the substrate 11, a first microstrip line 32 that is electromagnetically coupled to the slot line 22, and two second microstrip lines 33. The second microstrip lines 33 have a first coupling portion that is directly and electromagnetically coupled to the radiating slots 21 and a second coupling portion that is directly and electromagnetically coupled to the slot line 22. The impedance of the first coupling portion and the impedance of the second coupling portion are different.

Description

Technical Field

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

Background Art

[0002] Conventionally, for example, an array antenna including a parallel feeding circuit that excites a plurality of antenna elements provided on a dielectric substrate is known (see, for example, Non-Patent Document 1). The parallel feeding circuit realizes excitation with equal amplitude and equal phase regardless of frequency by making the line lengths to each antenna element the same. Conventionally, for example, as a parallel feeding circuit of an array antenna, a two-plane feeding circuit is known (see, for example, Non-Patent Document 2). This two-plane feeding circuit is formed by three microstrip lines provided on the surface of a dielectric substrate and a slot line provided on the ground conductor plate on the back surface of the dielectric substrate and orthogonal to the three microstrip lines on the surface. The two-plane feeding circuit generates a mirror-symmetrical current distribution to cancel out the cross-polarization components radiated from each antenna element, realizing a very low cross-polarization level.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in antenna technology that includes a dual-plane feeding circuit, it is desirable to suppress unwanted radiation generated from the feeding circuit located within the substrate containing the radiating section. For example, in the conventional planar array antenna described above, there is a risk of unwanted radiation being generated from the slot lines formed together with the radiating slots on the ground conductor plate on the back surface of the dielectric substrate.

[0005] The present invention aims to provide an antenna device that can suppress the generation of unwanted radiation. [Means for solving the problem]

[0006] In order to solve the above problems and achieve the above objectives, the present invention employs the following embodiments. (1) An antenna device according to one aspect of the present invention comprises a substrate, a first surface and a second surface provided on both sides of the substrate in the thickness direction, and a radiating portion provided on the first surface or the second surface and electromagnetically coupled with the feed circuit, wherein the feed circuit comprises a feed line provided on the same surface as the radiating portion among the first surface and the second surface, and a coupling line having a first coupling portion that is directly and electromagnetically coupled with the radiating portion and a second coupling portion that is directly and electromagnetically coupled with the feed line, wherein the impedance of the first coupling portion and the impedance of the second coupling portion are different.

[0007] (2) In the antenna device described in the embodiment of (1) above, the radiating section is a slot antenna, the coupling line is a microstrip line, and the width of the coupling line may change in an increasing manner as it moves from the first coupling section to the second coupling section, thereby causing the impedance of the coupling line to change in a decreasing manner.

[0008] (3) In the antenna device described in the embodiment of (1) above, the radiating section is a patch antenna, the coupling line is a slot line, and the line width of the coupling line changes in an increasing manner as it moves from the first coupling section to the second coupling section, thereby causing the impedance of the coupling line to change in an increasing manner.

[0009] (4) In the antenna device described in any one of the embodiments (1) to (3) above, the outer shape of the coupling line in a plan view along the thickness direction of the substrate may be tapered from the second coupling portion toward the first coupling portion.

[0010] (5) In the antenna device described in any one of the embodiments (1) to (3) above, the coupling line may include a quarter-wavelength transformer between the first coupling and the second coupling. [Effects of the Invention]

[0011] According to the embodiment of (1) above, by having different impedances for the first and second coupling sections of the coupling line, it is possible to reduce the impedance of the second coupling section while maintaining the impedance of the first coupling section. By reducing the impedance of the second coupling section, the width of the feed line provided on the same plane as the radiating section can be reduced, and unwanted radiation into free space can be suppressed.

[0012] In the embodiment described in (2) above, the microstrip line changes in width to an increasing trend as it moves from the first coupling to the second coupling, thereby changing the impedance to a decreasing trend, and making it possible to reduce the width of the slot line which is the power supply line.

[0013] In the embodiment described in (3) above, the slot line changes in width as it moves from the first coupling to the second coupling, thereby increasing the impedance and reducing the width of the microstrip line which is the power supply line.

[0014] In the case of the aspect of (4) above, the outer shape of the coupling line is tapered from the second coupling portion toward the first coupling portion, so that the impedance can be gradually changed.

[0015] In the case of the aspect of (5) above, the coupling line can change the impedance by including a quarter wavelength transformer between the first coupling portion and the second coupling portion.

Brief Description of the Drawings

[0016] [Figure 1] Exploded perspective view showing the configuration of the antenna device in an embodiment of the present invention. [Figure 2] Plan view seen from the positive side in the Z-axis direction showing the configuration of the antenna device in an embodiment of the present invention. [Figure 3] Plan view seen from the negative side in the Z-axis direction showing the configuration of the antenna device in an embodiment of the present invention. [Figure 4] Plan view showing a part of the configuration of the antenna device in an embodiment and a comparative example of the present invention. [Figure 5] Diagram schematically showing the configuration and impedance of the power supply circuit of the antenna device in an embodiment of the present invention. [Figure 6] Plan view seen from the positive side in the Z-axis direction showing the configuration of the antenna device in the first modification of an embodiment of the present invention. [Figure 7] Plan view seen from the negative side in the Z-axis direction showing the configuration of the antenna device in the first modification of an embodiment of the present invention. [Figure 8] Plan view seen from the positive side in the Z-axis direction showing the configuration of the antenna device in the second modification of an embodiment of the present invention. [Figure 9] Plan view seen from the negative side in the Z-axis direction showing the configuration of the antenna device in the second modification of an embodiment of the present invention. [Figure 10] Diagram schematically showing the configuration and impedance of the power supply circuit of the antenna device in the third modification of an embodiment of the present invention.

Mode for Carrying Out the Invention

[0017] Hereinafter, an antenna device according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an exploded perspective view showing the configuration of the antenna device 10 of the embodiment. FIG. 2 is a plan view of the antenna device 10 of the embodiment as viewed from the positive side in the Z-axis direction. FIG. 3 is a plan view of the antenna device 10 of the embodiment as viewed from the negative side in the Z-axis direction. Hereinafter, in the three-dimensional space, the axial directions of the X-axis, Y-axis, and Z-axis that are orthogonal to each other are directions parallel to each axis. For example, the Z-axis direction is parallel to the thickness direction of the antenna device 10, and the X-axis direction and the Y-axis direction are orthogonal to the thickness direction of the antenna device 10.

[0018] As shown in FIGS. 1, 2, and 3, the antenna device 10 of the embodiment is, for example, a 2×2 element array antenna including a two-plane feeding circuit. The antenna device 10 of the embodiment includes, for example, a substrate 11, a conductor plate 12, and a conductive layer 13. The outer shape of the substrate 11 is, for example, a rectangular plate shape. The substrate 11 is formed of a dielectric. The conductor plate 12 and the conductive layer 13 are provided so as to sandwich the substrate 11 from both sides in the thickness direction. For example, with respect to the first surface and the second surface that are both surfaces of the substrate 11 in the thickness direction, the conductor plate 12 is provided on the first surface, and the conductive layer 13 is provided on the second surface.

[0019] In the conductor plate 12, for example, four radiation slots 21 penetrating in the thickness direction and one slot line 22 are formed. For example, each of the four radiation slots 21 is a radiation part by a slot antenna, and one slot line 22 is a feeding line provided on the same surface as the radiation part.

[0020] Each of the four radial slots 21 is a so-called bowtie slot, formed, for example, by a pair of first slots 21a and second slots 21b. The outer shape of each of the first slots 21a and second slots 21b is, for example, an isosceles triangular through-hole. The first slots 21a and second slots 21b are formed, for example, by butting their vertices together in a point-symmetrical manner. The outer shape of one slot track 22 is, for example, an elongated rectangular through-hole. For example, the longitudinal direction of the slot track 22 is parallel to the X-axis direction, and the short direction of the slot track 22 is parallel to the Y-axis direction.

[0021] The four radial slots 21 are formed by, for example, two radial slots 21 formed along the short direction of the slot line 22, sandwiching the slot line 22 from both sides, forming a set of radial slot groups, and then arranging them side by side along the longitudinal direction of the slot line 22 to form two sets of radial slot groups. Each radial slot 21 is formed, for example, with the arrangement direction of the first slot 21a and the second slot 21b parallel to the longitudinal direction of the slot line 22.

[0022] The conductive layer 13 includes, for example, a first microstrip line 32 having a power supply section 31 and two second microstrip lines 33. For example, the first microstrip line 32, the two second microstrip lines 33, and one slot line 22 constitute a power supply circuit 34. Each of the two second microstrip lines 33 is a coupling line that electromagnetically connects the radiating section and the power supply line.

[0023] The power supply unit 31 is provided, for example, at the end of the first microstrip line 32, in a portion that is connected to a part of the outer circumferential surface of the substrate 11. The part of the outer circumferential surface of the substrate 11 is, for example, the surface in the Y-axis direction perpendicular to the thickness direction of the substrate 11. The outer shape of the first microstrip line 32 is, for example, an elongated rectangular plate. For example, the longitudinal direction of the first microstrip line 32 is parallel to the Y-axis direction, and the short direction of the first microstrip line 32 is parallel to the X-axis direction. At least one of the two ends of the first microstrip line 32 in the Y-axis direction is provided so as to be connected to a part of the outer surface of the substrate 11, thereby forming the power supply section 31.

[0024] For example, the first microstrip line 32 and the slot line 22 are positioned so that they are orthogonal to each other in a plan view from the Z-axis direction, and so that parts of them overlap. Parts of the first microstrip line 32 and the slot line 22 face each other along the Z-axis direction, with the substrate 11 in between. The first microstrip line 32 and the slot line 22 are directly and electromagnetically coupled through the parts of them that face each other in the Z-axis direction.

[0025] The shape of the second microstrip track 33 is, for example, an elongated plate shape. For example, similar to the first microstrip track 32, the longitudinal direction of the second microstrip track 33 is parallel to the Y-axis direction, and the short direction of the second microstrip track 33 is parallel to the X-axis direction. The two second microstrip tracks 33 are arranged, for example, along the short direction of the first microstrip track 32, sandwiching the first microstrip track 32 from both sides.

[0026] For example, each of the two second microstrip lines 33 and the slot line 22 are positioned perpendicular to each other in a plan view from the Z-axis direction. Each second microstrip line 33 and each group of radiating slots and slot line 22 are positioned so that parts of them overlap in a plan view from the Z-axis direction. For example, both ends 33a of each second microstrip line 33 in the Y-axis direction and the central part of each radiating slot 21 in each group of radiating slots face each other along the Z-axis direction, with the substrate 11 in between. The central part of each radiating slot 21 is, for example, the part that includes the vertices that meet each other in the first slot 21a and the second slot 21b. For example, the central part 33b of each second microstrip line 33 and a part of the slot line 22 face each other along the Z-axis direction, with the substrate 11 in between. Each second microstrip line 33 and each group of radiating slots and slot line 22 are directly and electromagnetically coupled through their opposing parts in the Z-axis direction.

[0027] Figure 4 is a plan view showing some of the configurations of the antenna devices 10 and 40 in the embodiment and comparative example. Note that parts of the antenna device 40 in the comparative example that are the same as those in the antenna device 10 of the embodiment described above are denoted by the same reference numerals. As shown in Figure 4, in the comparative example antenna device 40, the slot line 41 and second microstrip line 42 of the comparative example are formed instead of the slot line 22 and second microstrip line 33 of the antenna device 10 of the embodiment.

[0028] For example, the track width W1 in the Y-axis direction of the slot track 22 in the embodiment is formed to be smaller than the track width W2 in the Y-axis direction of the slot track 41 in the comparative example. The track width in the X-axis direction of the second microstrip track 33 in the embodiment tends to increase as it moves from both ends 33a to the central part 33b. The track width Lb in the X-axis direction of the central part 33b is formed to be larger than the track width La in the X-axis direction of both ends 33a. In other words, the outer shape of the second microstrip track 33 in a plan view along the Z-axis direction is, for example, tapered from the central part 33b to both ends 33a. The track width in the X-axis direction of the second microstrip track 42 in the comparative example is constant and is the same as the track width La of both ends 33a of the second microstrip track 33 in the embodiment. In other words, the outer shape of the second microstrip track 42 in the comparative example is rectangular.

[0029] In the embodiment, the ends 33a of the second microstrip line 33 and the central part of the radiating slot 21 form a first coupling, which is directly and electromagnetically coupled. The central part 33b of the second microstrip line 33 and a part of the slot line 22 form a second coupling, which is directly and electromagnetically coupled. Similarly, in the comparative example of the second microstrip line 42, the ends 42a in the Y-axis direction and the central part of the radiating slot 21 form a first coupling, which is directly and electromagnetically coupled, and the central part 42b in the Y-axis direction and a part of the slot line 41 form a second coupling, which is directly and electromagnetically coupled.

[0030] Since the line width La at both ends 33a and 42a of the second microstrip lines 33 and 42 in the embodiment and comparative example is the same, the characteristic impedance of the first coupling in the embodiment and comparative example is the same. Since the line width Lb of the central part 33b of the second microstrip line 33 in the embodiment is greater than the line width La of the central part 42b of the second microstrip line 42 in the comparative example, the characteristic impedance of the second coupling in the embodiment is smaller than the characteristic impedance of the second coupling in the comparative example and the characteristic impedance of the first coupling in the embodiment. Due to impedance matching between each second microstrip line 33 and 42 and each slot line 22 and 41, the line width W1 of the slot line 22 in the embodiment is formed to be smaller than the line width W2 of the slot line 41 in the comparative example. In other words, the characteristic impedance of the slot line 22 in the embodiment is smaller than the characteristic impedance of the slot line 41 in the comparative example.

[0031] Figure 5 is a schematic diagram showing the configuration and impedance of the feeding circuit 34 in the antenna device 10 of the embodiment. In the feeding circuit 34 shown in Figure 5, the input impedance of each radiating slot 21 is a first predetermined value (=A(Ω)). The input impedance of each radiating slot 21 is, for example, the characteristic impedance Z of the central part (i.e., the first coupling part) P1, P2, P3, P4 of each radiating slot 21. In this case, due to impedance matching, the characteristic impedance Z of the coupling part (third coupling part) P5 between the first microstrip line 32 and the slot line 22 is a first predetermined value (=A(Ω)). The characteristic impedance Z of the coupling parts (second coupling part) P6, P7 between the second microstrip line 33 and the slot line 22 is a second predetermined value (=2A(Ω)) which is twice the first predetermined value (=A(Ω)).

[0032] As described above, according to the antenna device 10 of the embodiment, the characteristic impedance of the central portion 33b (second coupling portion) of the second microstrip line 33 is smaller than the characteristic impedance of both ends 33a (first coupling portion). By lowering the characteristic impedance of the second coupling portion while maintaining the characteristic impedance of the first coupling portion, the width of the slot line 22 (feed line) provided on the same plane as the radiating slot 21 (radiating portion) can be reduced, and unwanted radiation into free space can be suppressed.

[0033] As the second microstrip line 33 moves from the first connection to the second connection, its width tends to increase, which causes its characteristic impedance to decrease, thereby reducing the width of the slot line 22, which is the power supply line. The shape of the second microstrip line 33 tapers from the second joint to the first joint, allowing the characteristic impedance to be gradually changed.

[0034] (modified version) Modified examples of the embodiments are described below. Note that parts identical to those in the embodiments described above are denoted by the same reference numerals, and their descriptions are omitted or simplified. In the embodiment described above, the radiating portion is a radiating slot 21, the power supply line provided on the same plane as the radiating portion is a slot line 22, and the coupling line that electromagnetically connects the radiating portion and the power supply line is a second microstrip line 33, but the embodiment is not limited to this. For example, the slot and the strip conductor may be interchanged.

[0035] Figure 6 is a plan view taken from the positive Z-axis direction, showing the configuration of the antenna device 10A in the first modified embodiment. Figure 7 is a plan view taken from the negative Z-axis direction, showing the configuration of the antenna device 10A in the first modified embodiment. As shown in Figures 6 and 7, the first modified antenna device 10A includes, for example, a substrate 11, a conductive plate 12A provided on the first surface of the substrate 11, and a conductive layer 13A provided on the second surface of the substrate 11.

[0036] The conductive layer 13A comprises, for example, four radiating conductors 51 and one microstrip line 52. For example, each of the four radiating conductors 51 is a radiating section of a so-called patch antenna, and the one microstrip line 52 is a feed line provided on the same plane as the radiating sections. Each of the four radiating conductors 51 is a so-called bowtie-type microstrip conductor, formed, for example, by a pair of first microstrip conductors 51a and second microstrip conductors 51b. The outer shape of each of the first microstrip conductors 51a and second microstrip conductors 51b is, for example, an isosceles triangular plate. The first microstrip conductors 51a and second microstrip conductors 51b are formed, for example, with their vertices abutting each other in a point-symmetrical manner. The shape of one microstrip track 52 is, for example, an elongated rectangular plate. For example, the longitudinal direction of the microstrip track 52 is parallel to the X-axis direction, and the short direction of the microstrip track 52 is parallel to the Y-axis direction.

[0037] The four radiating conductors 51 constitute two sets of radiating conductors arranged side by side along the longitudinal direction of the microstrip line 52, with each set consisting of two radiating conductors 51 formed to sandwich the microstrip line 52 from both sides along the short direction of the microstrip line 52. Each radiating conductor 51 is arranged, for example, with the arrangement direction of the first microstrip conductor 51a and the second microstrip conductor 51b parallel to the longitudinal direction of the microstrip line 52.

[0038] The conductor plate 12A has, for example, a first slot line 61 and two second slot lines 62 that penetrate in the thickness direction. For example, the first slot line 61, the two second slot lines 62, and one microstrip line 52 constitute a power supply circuit. Each of the two second slot lines 62 is a coupling line that electromagnetically connects the radiating section and the power supply line.

[0039] The outer shape of the first slot line 61 is, for example, an elongated rectangular through-hole. For example, the longitudinal direction of the first slot line 61 is parallel to the Y-axis direction, and the short direction of the first slot line 61 is parallel to the X-axis direction. At least one of the two ends of the first slot line 61 in the Y-axis direction is opened on the outer surface of the conductor plate 12A to form a power supply section 63.

[0040] For example, the first slot line 61 and the microstrip line 52 are positioned so that they are orthogonal to each other in a plan view from the Z-axis direction, and so that parts of them overlap. Parts of the first slot line 61 and the microstrip line 52 face each other along the Z-axis direction, with the substrate 11 in between. The first slot line 61 and the microstrip line 52 are directly and electromagnetically coupled through the parts of them that face each other in the Z-axis direction.

[0041] The outer shape of the second slot track 62 is, for example, an elongated rectangular through-hole. For example, similar to the first slot track 61, the longitudinal direction of the second slot track 62 is parallel to the Y-axis direction, and the short direction of the second slot track 62 is parallel to the X-axis direction. The two second slot tracks 62 are arranged, for example, along the short direction of the first slot track 61, sandwiching the first slot track 61 from both sides.

[0042] For example, each of the two second slot lines 62 and the microstrip line 52 are positioned perpendicular to each other in a plan view from the Z-axis direction. Each second slot line 62, each group of radiating conductors, and the microstrip line 52 are positioned so that parts of them overlap in a plan view from the Z-axis direction. For example, both ends 62a of each second slot line 62 in the Y-axis direction and the central part of each radiating conductor 51 in each group of radiating conductors face each other along the Z-axis direction, with the substrate 11 in between. The central part of each radiating conductor 51 is, for example, the part that includes the vertices that meet each other in the first microstrip conductor 51a and the second microstrip conductor 51b. For example, the central part 62b of each second slot line 62 and a part of the microstrip line 52 face each other along the Z-axis direction, with the substrate 11 in between. Each second slot line 62, each group of radiating conductors, and the microstrip line 52 are directly and electromagnetically coupled through their opposing parts in the Z-axis direction.

[0043] The track width of the second slot track 62 in the X-axis direction tends to increase as it moves from both ends 62a towards the central part 62b. For example, the track width in the X-axis direction at both ends 62a is the same as the track width La in the embodiment described above, and the track width in the X-axis direction at the central part 62b is the same as the track width Lb in the embodiment described above. The track width Lb in the X-axis direction at the central part 62b is formed to be larger than the track width La at both ends 62a. In other words, the outer shape of the second slot track 62 is tapered (so-called tapered shape) from the central part 62b towards both ends 62a.

[0044] In the first modified example, the ends 62a of the second slot line 62 and the central part of the radiating conductor 51 form a first coupling that is directly and electromagnetically coupled. The central part 62b of the second slot line 62 and a portion of the microstrip line 52 form a second coupling that is directly and electromagnetically coupled. Because the line width Lb of the central part 62b of the second slot line 62 is greater than the line width La of the ends 62a, the characteristic impedance of the second coupling in the first modified example is greater than the characteristic impedance of the first coupling in the first modified example. Due to impedance matching between each second slot line 62 and the microstrip line 52, the line width W1 of the microstrip line 52 in the first modified example is formed to be smaller than, for example, the line width W1 of the second slot line 62 is constant (i.e., a constant line width La from both ends 62a to the central part 62b).

[0045] According to the first modified example, the second slot line 62 changes in impedance as its width increases from both ends 62a (first coupling section) towards the central section 62b (second coupling section). This allows for a reduction in the width of the microstrip line 52, which is the feed line electromagnetically coupled to the central section 62b (second coupling section), thereby suppressing unwanted radiation into free space.

[0046] In the embodiments described above, the external shape of the second microstrip line 33 is tapered from the central portion 33b to both ends 33a (a so-called tapered shape), but it is not limited to this. For example, instead of having a tapered external shape that gradually changes the characteristic impedance, it may be equipped with at least one quarter-wavelength transformer.

[0047] Figure 8 is a plan view from the positive Z-axis direction showing the configuration of the antenna device 10B in the second modified embodiment. Figure 9 is a plan view from the negative Z-axis direction showing the configuration of the antenna device 10B in the second modified embodiment. As shown in Figures 8 and 9, the second modified antenna device 10B includes, for example, a substrate 11, a conductive plate 12 provided on the first surface of the substrate 11, and a conductive layer 13B provided on the second surface of the substrate 11 instead of the conductive layer 13 of the embodiment.

[0048] The conductive layer 13B of the second modified example comprises, for example, a first microstrip line 32 having a power supply section 31 and two third microstrip lines 71. For example, the first microstrip line 32, the two third microstrip lines 71, and one slot line 22 constitute a power supply circuit. Each of the two third microstrip lines 71 is a coupling line that electromagnetically connects the radiating section to the power supply line.

[0049] The external shape of the third microstrip line 71 in the second modified example is, for example, an elongated plate shape. For example, the longitudinal direction of the third microstrip line 71 is parallel to the Y-axis direction, and the short direction of the third microstrip line 71 is parallel to the X-axis direction. The two third microstrip lines 71 are arranged, for example, along the short direction of the first microstrip line 32, sandwiching the first microstrip line 32 from both sides.

[0050] The third microstrip line 71 of the second modified example includes, for example, a quarter-wavelength transformer 71c between the end sections 71a and the central section 71b, where the line width in the X-axis direction is constant. The outer shape of the quarter-wavelength transformer 71c is, for example, a plate shape that increases the line width in the X-axis direction in two steps, from the line width La in the X-axis direction at both end sections 71a to the line width Lb (>La) in the X-axis direction at the central section 71b.

[0051] For example, each of the two third microstrip lines 71 and the slot line 22 are positioned perpendicular to each other in a plan view from the Z-axis direction. Each third microstrip line 71 and each group of radiating slots and slot line 22 are positioned so that parts of them overlap in a plan view from the Z-axis direction. For example, both ends 71a of each third microstrip line 71 in the Y-axis direction and the central part of each radiating slot 21 in each group of radiating slots face each other along the Z-axis direction, with the substrate 11 in between. For example, the central part 71b of each third microstrip line 71 and a part of the slot line 22 face each other along the Z-axis direction, with the substrate 11 in between. Each third microstrip line 71 and each group of radiating slots and slot line 22 are directly and electromagnetically coupled through their opposing parts in the Z-axis direction.

[0052] According to the second modified example, the third microstrip line 71 can change its characteristic impedance between the first and second coupling sections by including a quarter-wavelength transformer 71c. In the second modified example described above, instead of a single quarter-wavelength transformer 71c, multiple quarter-wavelength transformers 71c connected in stages may be provided. Furthermore, in the first modified example described above, the outer shape of the second slot line 62 is tapered from the central part 62b to both ends 62a (a so-called tapered shape), but it is not limited to this. For example, instead of having a tapered outer shape that gradually changes the characteristic impedance, at least one quarter-wavelength transformer may be formed.

[0053] In the embodiment described above, the antenna device 10 is a 2x2 element array antenna equipped with a double-plane feeding circuit, but it is not limited to this. For example, the number of elements may be set arbitrarily. Figure 10 is a schematic diagram showing the configuration and impedance of the feed circuit 34A of the antenna device 10C in a third modified example of the embodiment. As shown in Figure 10, the third modified antenna device 10C is, for example, a 4x4 element array antenna equipped with a double-plane feeding circuit.

[0054] In the third modified power supply circuit 34A shown in Figure 10, the input impedance of each radiating slot 21 is a first predetermined value (=A(Ω)). The input impedance of each radiating slot 21 is, for example, the characteristic impedance Z of the central part (i.e., the first coupling part) R1 of each radiating slot 21. In this case, due to impedance matching, the characteristic impedance Z of the coupling part (third coupling part) R2 between the first microstrip line 32 and the slot line 22 is a first predetermined value (=A(Ω)). The characteristic impedance Z of the coupling part (second coupling part) R3 between the second microstrip line 33 and the slot line 22 is a second predetermined value (=2A(Ω)), which is twice the first predetermined value (=A(Ω)).

[0055] In the third modified power supply circuit 34A, a slot line 81 is formed that is directly and electromagnetically coupled to a plurality of first microstrip lines 32, and a microstrip line 82 is formed that is directly and electromagnetically coupled to the slot line 81 for power supply. The characteristic impedance Z of the coupling part R4 between the slot line 81 and the microstrip line 82 is a first predetermined value (=A(Ω)). The characteristic impedance Z of the coupling part R5 between the two first microstrip lines 32 and the slot line 81 is a second predetermined value (=2A(Ω)) which is twice the first predetermined value (=A(Ω)).

[0056] In the embodiments and modifications described above, the outer shape of the radial section is bowtie-shaped, but it is not limited to this and may be other shapes such as closed figures. For example, it may be a square, polygon, circle, ellipse, ring, cross, or leaf-shaped bowtie.

[0057] In the embodiment described above, the antenna device 10 may be unidirectional, for example, by providing a reflector on the substrate 11 opposite to the radiation slot 21 along the Z-axis direction. The reflector may be arranged such that, for example, an air layer, a dielectric substrate having a conductive layer, or a dielectric layer is sandwiched between it and the conductive layer 13 via a spacer.

[0058] In the embodiment described above, the antenna device 10 may change the direction of the beam output from the radiating section by, for example, providing a phase shifter in the feeding circuit 34.

[0059] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0060] 10, 10A, 10B, 10C… Antenna device, 11… Substrate, 12, 12A… Conductor plate, 13, 13A, 13B… Conductive layer, 21… Radiation slot (radiating part), 21a… First slot, 21b… Second slot, 22… Slot line, 31… Feed section, 32… First microstrip line, 33… Second microstrip line, 33a… Both ends (first connection), 33b… Center (second connection), 34, 34A ...power supply circuit, 51...radiating conductor (radiating part), 51a...first microstrip conductor, 51b...second microstrip conductor, 52...microstrip line, 61...first slot line, 62...second slot line, 62a...both ends (first connection part), 62b...center part (second connection part), 63...power supply part, 71...third microstrip line, 71a...both ends (first connection part), 71b...center part (second connection part).

Claims

1. circuit board and A power supply circuit is provided on the first and second surfaces, which are both surfaces in the thickness direction of the substrate, A radiating portion provided on the first or second surface and electromagnetically coupled to the power supply circuit Equipped with, The aforementioned power supply circuit is A power supply line provided on the same surface as the radiating portion, among the first and second surfaces, A coupling line having a first coupling portion that is directly and electromagnetically coupled to the radiating portion and a second coupling portion that is directly and electromagnetically coupled to the power supply line. Equipped with, The impedance of the first coupling and the impedance of the second coupling are different. Antenna device.

2. The aforementioned radiating section is a slot antenna, The aforementioned coupling line is a microstrip line, The width of the coupling line tends to increase as it moves from the first coupling point to the second coupling point, thereby causing the impedance of the coupling line to tend to decrease. The antenna device according to claim 1.

3. The aforementioned radiating section is a patch antenna, The aforementioned coupling line is a slot line, The width of the coupling line tends to increase as it moves from the first coupling point to the second coupling point, thereby causing the impedance of the coupling line to change in an increasing trend. The antenna device according to claim 1.

4. In a plan view along the thickness direction of the substrate, the outer shape of the coupling line tapers from the second coupling portion to the first coupling portion. The antenna device according to any one of claims 1 to 3.

5. The coupling line includes a quarter-wavelength transformer between the first coupling section and the second coupling section. The antenna device according to any one of claims 1 to 3.

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