Antenna equipment

Abstract

To provide an antenna device having directivity with a structure capable of being miniaturized while increasing bandwidth than before.SOLUTION: An antenna device 10a includes: a radiator 13 that has a plate-like first antenna element 11 and a plate-like second antenna element 12 placed on the same plane as the first antenna element 11 with the width smaller than that of the first antenna element 11 having one side 12a which is connected to the one side 11a of the first antenna element 11 via a power supply part; a parasitic element 16 placed on the same plane as the radiator 13 without being connected to the radiator 13, and placed in a position overlapping at least a portion of each of the first antenna element 11 and the second antenna element 12 when looking at the parasitic element 16 in the x-axis direction; and a parasitic reflective plate 14 which is placed on a plane facing the radiator 13 and the parasitic element 16, and has a plate shape extending in the y-axis direction, with the width in the x-axis direction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present disclosure relates to an antenna device, and more particularly to an antenna device having directivity and a structure that can be miniaturized.

Background Art

[0002] In recent years, the spread of IoT (Internet of Things) terminals has been rapidly progressing worldwide. Antennas for IoT terminals are required to be miniaturized from the viewpoints of design and mobility. In addition, when there are human bodies or metal objects near the antenna, its performance deteriorates, so it is necessary to be strong against surrounding objects. In order to reduce the influence of surrounding metal objects or the like, an antenna having single directivity is effective. Therefore, it is desirable for antennas for IoT terminals to be small and have single directivity.

[0003] Therefore, conventionally, an antenna device has been proposed that includes a power-free reflector provided opposite to a radiator and has a structure that can be miniaturized by enhancing the directivity to the side opposite to the reflector by electromagnetic coupling between the radiator and the reflector (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, although the antenna device of Patent Document 1 has a structure that enables miniaturization with enhanced directivity, further broadbanding is required depending on the communication system.

[0006] Therefore, an object of the present disclosure is to provide an antenna device having directivity and a structure that can be miniaturized, and having a broader bandwidth than conventional ones. [Means for solving the problem]

[0007] To achieve the above objective, an antenna device according to one embodiment of the present disclosure is a directional antenna device used in connection with a feed unit, comprising: a radiator having a plate-shaped first antenna element having a width in a first direction and extending in a second direction perpendicular to the first direction, and a second antenna element arranged on the same plane as the first antenna element, having a narrower width than the first antenna element and having one side connected to one side of the first antenna element via the feed unit; and a parasitic element arranged on the same plane as the radiator and not connected to the radiator, wherein when the parasitic element is viewed in the first direction, the first antenna element and the second antenna element are... The antenna device comprises a parasitic element positioned to overlap at least a portion thereof, and a parasitic reflector positioned in a plane facing the radiator and the parasitic element, having a width in the first direction and extending in the second direction, wherein the reflector has a length longer than the radiator, the second antenna element has a length shorter than 1 / 4 of the wavelength of the operating frequency, the radiator and the parasitic element and the reflector are spaced apart to allow electromagnetic coupling, the resistance component of the input impedance of the antenna device is adjusted by the length of the first antenna element, and the reactance component of the input impedance of the antenna device is adjusted by the length of the second antenna element. The passive element is positioned such that, when viewed in the first direction, it overlaps with a portion of the first antenna element and with the entirety of the second antenna element. [Effects of the Invention]

[0008] This disclosure provides an antenna device that is directional, has a miniaturizable structure, and offers a wider bandwidth than conventional antenna devices. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an external view showing the structure of the antenna device according to the first reference example. [Figure 2] Figure 2 shows the antenna characteristics of the antenna device according to the first reference example. [Figure 3]Figure 3 is a Smith chart showing the impedance characteristics when the length of the first antenna element is changed by 1 mm increments in the antenna device according to the first reference example. [Figure 4] Figure 4 is a Smith chart showing the impedance characteristics of the antenna device according to the first reference example when the length of the second antenna element is changed in 1 mm increments. [Figure 5] Figure 5 is an external view showing the structure of the antenna device according to the second reference example. [Figure 6] Figure 6 shows the antenna characteristics of the antenna device according to the second reference example. [Figure 7] Figure 7 is an external view showing the structure of the antenna device according to Embodiment 1. [Figure 8] Figure 8 shows the antenna characteristics of the antenna device according to Embodiment 1. [Figure 9] Figure 9 is an external view showing the structure of the antenna device according to Embodiment 2. [Figure 10] Figure 10 shows the antenna characteristics of the antenna device according to Embodiment 2. [Figure 11] Figure 11 is an external view showing the structure of the antenna device according to Embodiment 3. [Figure 12] Figure 12 shows the antenna characteristics of the antenna device according to Embodiment 3. [Figure 13] Figure 13 is an external view showing the structure of the antenna device according to Embodiment 4. [Figure 14] Figure 14 shows the antenna characteristics of the antenna device according to Embodiment 4. [Figure 15] Figure 15 is an external view showing the structure of the antenna device according to Embodiment 5. [Figure 16] Figure 16 shows the antenna characteristics of the antenna device according to Embodiment 5. [Figure 17] Figure 17 is an external view showing the structure of the antenna device according to Embodiment 6. [Figure 18] Figure 18 shows the antenna characteristics of the antenna device according to Embodiment 6.

Best Mode for Carrying Out the Invention

[0010] (Antenna Device According to Reference Example) Before describing embodiments of the present disclosure, two examples of an antenna device for the 2.4 GHz band (the operating frequency is 2.45 GHz, which is the approximate center frequency, and the wavelength is about 122 mm) based on the technology according to Patent Document 1 will be described as an antenna device according to a reference example.

[0011] (First Reference Example) FIG. 1 is an external view showing the structure of an antenna device 9a according to the first reference example. More specifically, FIGS. 1(a) to 1(f) are a perspective view, a top view, a bottom view, a side view, a dimensional view on the top surface, and a dimensional view on the bottom surface of the antenna device 9a, respectively. The antenna device 9a is generally long and rectangular. The width direction is defined as the x-axis (also referred to as the "first direction"), the direction perpendicular to the x-axis and extending long is defined as the y-axis (also referred to as the "second direction"), and the direction perpendicular to the x-axis and the y-axis is defined as the z-axis.

[0012] The antenna device 9a is a directional antenna connected to a power supply unit (not shown) and used, and includes a plate-shaped first antenna element 11 having a width in the x-axis direction and extending in the y-axis direction, and a plate-shaped element arranged on the same plane as the first antenna element 11, having a width in the x-axis direction and extending in the y-axis direction, and having a width smaller than that of the first antenna element 11, and a radiator 13 having a side 12a connected to one side 11a of the first antenna element 11 via a power supply unit. The radiator 13 is provided with a plate-shaped reflector 14 arranged on a plane facing the radiator 13, having a width in the x-axis direction and extending in the y-axis direction, and without power supply. Note that the second antenna element 12 may be in an inverted L shape, and its shape is not limited to being straight.

[0013] Here, the reflector 14 has a length longer than the radiator 13, the second antenna element 12 has a length shorter than 1 / 4 of the wavelength of the operating frequency, and the radiator 13 and the reflector 14 are spaced apart to allow electromagnetic coupling. The reflector 14 may have a length that functions as a reflector, and may be at least 1 / 2 of the wavelength of the operating frequency. The resistive component of the input impedance of the antenna device 9a is adjusted by the length of the first antenna element 11, and the reactance component of the input impedance of the antenna device 9a is adjusted by the length of the second antenna element 12.

[0014] Furthermore, when specifying the length or width of each component using the wavelength (λ) of the operating frequency, the wavelength (λ) may be the value obtained by multiplying it by the wavelength shortening factor determined according to the relative permittivity of each component (electrical length). Also, "plate-shaped" means a flat plate whose length or width is sufficiently large compared to its thickness (for example, more than twice as large), and the external shape in plan view is not limited to a rectangle, but may be any shape such as an ellipse. "Rectangular" means a rectangle. Furthermore, when simply written as "plan view," it means a plan view relative to the antenna device.

[0015] The specific structure of the antenna device 9a is as follows:

[0016] A substrate 15 made of FR-4 (Flame Retardant Type 4) with a relative permittivity εr = 4.6 is used. The external dimensions of the substrate 15 are length L50 mm × width W6 mm × thickness t1.2 mm. Both the radiator 13 (first antenna element 11 and second antenna element 12) and the reflector 14 are formed from copper foil on the substrate 15.

[0017] The antenna device 9a consists of a radiator 13, which is formed by connecting a power supply unit to the gap g between a first antenna element 11 with length l1 × width w1 and a second antenna element 12 with length l2 × width w2, and a reflector 14 with length l3 × width w3. The distance from the edge of the substrate (the edge of the substrate 15 in the positive y-axis direction) to the first antenna element 11 is d, and the area 0.5 mm from the edge of the substrate (0.5 mm from the four edges toward the center on both sides of the substrate 15) is a prohibited area for copper foil patterns.

[0018] The resonant frequency of the antenna device 9a can be tuned by controlling the resistive component of the impedance of the antenna device 9a with the length l1 of the first antenna element 11, and by controlling the reactance component of the impedance of the antenna device 9a with the length l2 of the second antenna element 12.

[0019] In the antenna device 9a of this reference example, the second antenna element 12 is positioned such that the center of one side 11a of the first antenna element 11 faces one side 12a of the second antenna element 12. The dimensions are, for example, L=50mm, W=6mm, t=1.2mm, d=17mm, g=0.5mm, l1=25.5mm, w1=5mm, l2=9mm, w2=1mm, l3=49mm, and w3=5mm.

[0020] To explain each of these dimensions in relation to the wavelength λ (approximately 122 mm, electrical length approximately 57 mm (=122 / √4.6)) at the operating frequency (2.45 GHz), the length l1 of the first antenna element 11 is approximately 0.4 (=25.5 × √4.6 / 122)λ, and the length l2 of the second antenna element 12 is approximately 0.2 (=9 × √4.6 / 122)λ.

[0021] Power is supplied from the feed unit (not shown) to the radiator 13 from the top side of the antenna device 9a. The gap between one side 11a of the first antenna element 11 and one side 12a of the second antenna element 12, which are connected to the feed unit (not shown), is also called the "feed point".

[0022] Figure 2 shows the antenna characteristics of the antenna device 9a according to the first reference example shown in Figure 1. More specifically, Figure 2(a) is a Smith chart showing the impedance characteristics of the antenna device 9a according to the first reference example, and Figure 2(b) shows the VSWR (Voltage Standing Wave Ratio) characteristics of the antenna device 9a according to the first reference example. As can be seen from Figure 2(a), the antenna device 9a according to the first reference example is resonant at the operating frequency (2.45 GHz). Also, as can be seen from Figure 2(b), the antenna device 9a according to the first reference example has a bandwidth of 420 MHz for VSWR ≤ 2.

[0023] Figure 3 is a Smith chart showing the impedance characteristics of the antenna device 9a according to the first reference example shown in Figure 1, when the length l1 of the first antenna element 11 is changed in 1 mm increments from 23.5 mm to 27.5 mm. Here, dimensions other than the length l1 of the first antenna element 11 are fixed. As can be seen from Figure 3, the resistance component of the impedance of the antenna device 9a is controlled by the length l1 of the first antenna element 11.

[0024] Figure 4 is a Smith chart showing the impedance characteristics of the antenna device 9a according to the first reference example shown in Figure 1, when the length l2 of the second antenna element 12 is changed from 7 mm to 11 mm in 1 mm increments. Here, dimensions other than the length l2 of the second antenna element 12 are fixed. As can be seen from Figure 4, the reactance component of the impedance of the antenna device 9a is controlled by the length l2 of the second antenna element 12.

[0025] (2nd reference example) Figure 5 is an external view showing the structure of the antenna device 9b according to the second reference example. More specifically, Figures 5(a) to (f) are a perspective view, top view, bottom view, side view, top dimension view, and bottom dimension view of the antenna device 9b, respectively. The antenna device 9b has the same configuration as the antenna device 9a according to the first reference example, except for the arrangement position and size of the second antenna element 12.

[0026] In other words, in the antenna device 9b according to the second reference example, one side 12a of the second antenna element 12 faces the first end 11b of one side 11a of the first antenna element 11. That is, one side 12a of the second antenna element 12 is positioned not in the center of one side 11a of the first antenna element 11, but at a position corresponding to the first end 11b. The size of the second antenna element 12 is a length l2 of 9.5 mm, or approximately 0.2 (=9.5 × √4.6 / 122)λ. All other dimensions are the same as those of the antenna device 9a according to the first reference example.

[0027] Figure 6 shows the antenna characteristics of the antenna device 9b according to the second reference example shown in Figure 5. More specifically, Figure 6(a) is a Smith chart showing the impedance characteristics of the antenna device 9b according to the second reference example, and Figure 6(b) shows the VSWR characteristics of the antenna device 9b according to the second reference example. As can be seen from Figure 6(a), the antenna device 9b according to the second reference example resonates at the operating frequency (2.45 GHz), similar to the antenna device 9a according to the first reference example. Also, as can be seen from Figure 6(b), the antenna device 9b according to the second reference example has a bandwidth of 420 MHz for VSWR ≤ 2, similar to the antenna device 9a according to the first reference example.

[0028] Thus, the antenna device 9a according to the first reference example and the antenna device 9b according to the second reference example have a directional structure that can reduce the influence of surrounding metal objects, etc., by being provided with a reflector 14, and also have a compact structure.

[0029] (Antenna device according to an embodiment) In the following, examples of further widening of the antenna bandwidth are described in Embodiments 1 to 6 as examples of improving the antenna performance of the antenna device 9a according to the first reference example and the antenna device 9b according to the second reference example.

[0030] The embodiments of this disclosure will be described in detail below with reference to the drawings. The embodiments described below are all specific examples of this disclosure. The numerical values, shapes, materials, components, arrangement positions of components, and connection configurations shown in the following embodiments are examples only and are not intended to limit this disclosure. Furthermore, the figures are not necessarily strictly illustrative. In each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations are omitted or simplified. The meanings of terms and the x, y, and z axes are the same as those described for antenna device 9a in the first reference example and antenna device 9b in the second reference example.

[0031] Each embodiment is based on the antenna device 9a according to the first reference example, the antenna device 9b according to the second reference example, or an antenna device similar thereto, and incorporates improvements. The improvements will be described below in detail.

[0032] (Embodiment 1) First, let me describe the antenna device according to Embodiment 1 of this disclosure.

[0033] Figure 7 is an external view showing the structure of the antenna device 10a according to Embodiment 1. More specifically, Figures 7(a) to (d) are a perspective view, top view, bottom view, and top dimension view of the antenna device 10a, respectively. The antenna device 10a is based on the antenna device 9a according to the first reference example shown in Figure 1, and is characterized by having a parasitic element 16 arranged on the same plane as the radiator 13. The width of the first antenna element 11 is smaller than that of the antenna device 9a according to the first reference example.

[0034] The parasitic element 16 is positioned on the same plane as the radiator 13 and is not connected to the radiator 13. When viewed in the x-axis direction, the parasitic element 16 is positioned to overlap with at least a portion of the first antenna element 11 and the second antenna element 12. In this case, when viewed in the x-axis direction, the parasitic element 16 is positioned to overlap with a portion of the first antenna element 11 and with all of the second antenna element 12.

[0035] More specifically, when the antenna device 10a is viewed from above, the unpowered element 16 has a plate-shaped first portion 161 extending in the y-axis direction on one side in the x-axis direction of the first antenna element 11 and the second antenna element 12, a plate-shaped second portion 162 extending in the y-axis direction on the other side in the x-axis direction of the first antenna element 11 and the second antenna element 12, and a third portion 163 connecting the first portion 161 and the second portion 162.

[0036] Regarding the specific dimensions, as shown in Figure 7(d), the length l1 of the first antenna element 11 is 22 mm and the width w1 is 2 mm, while the length l2 of the second antenna element 12 is 11 mm and the width w2 is 1 mm. The unpowered element 16 has a gap of 0.5 mm from the first antenna element 11 and a gap of 1 mm from the second antenna element 12. The length of the first part 161 and the second part 162 is 25 mm and the width is 1 mm, while the length of the third part 163 (including the first part 161 and the second part 162) is 4 mm and the width is 5 mm.

[0037] To explain the relationship between each of these lengths and the wavelength λ (approximately 122 mm, electrical length approximately 57 mm (=122 / √4.6)) at the operating frequency (2.45 GHz), the length l1 of the first antenna element 11 is approximately 0.4 (=22 × √4.6 / 122)λ, the length l2 of the second antenna element 12 is approximately 0.2 (=11 × √4.6 / 122)λ, and the length of the unpowered element 16 is approximately 0.4 (=25 × √4.6 / 122)λ.

[0038] Figure 8 shows the antenna characteristics of the antenna device 10a according to Embodiment 1 shown in Figure 7. More specifically, Figure 8(a) is a Smith chart showing the impedance characteristics of the antenna device 10a according to Embodiment 1, Figure 8(b) shows the VSWR characteristics of the antenna device 10a according to Embodiment 1, and Figure 8(c) shows the current flow in the antenna device 10a according to Embodiment 1.

[0039] As can be seen from Figure 8(a), the antenna device 10a according to Embodiment 1 is resonating at the operating frequency (2.45 GHz).

[0040] Furthermore, as can be seen from Figure 8(b), the antenna device 10a according to Embodiment 1 has a bandwidth of 580 MHz for VSWR ≤ 2, which is wider than the bandwidth (420 MHz) of the antenna device 9a according to the base first reference example.

[0041] Furthermore, as can be seen from Figure 8(c), current flows through the parasitic element 16 in the same direction (i.e., in phase) as the first antenna element 11 and the second antenna element 12. This is considered to be the reason why the antenna device 10a according to Embodiment 1 has a wider bandwidth without degrading its performance.

[0042] As described above, the antenna device 10a according to this embodiment is a directional antenna device 10a used in connection with a power supply unit, comprising a radiator 13 having a plate-shaped first antenna element 11 having a width in the x-axis direction and extending in the y-axis direction, and a second antenna element 12 arranged on the same plane as the first antenna element 11, having a plate-shaped structure with a width in the x-axis direction and extending in the y-axis direction, having a narrower width than the first antenna element 11, and having one side 12a connected to one side 11a of the first antenna element 11 via a power supply unit, and a parasitic element 16 arranged on the same plane as the radiator 13 and not connected to the radiator 13, wherein when the parasitic element 16 is viewed in the x-axis direction, it overlaps with at least a portion of each of the first antenna element 11 and the second antenna element 12. The antenna device 10a comprises a parasitic element 16 positioned at a specific location, and a parasitic reflector 14 positioned in a plane opposite to the radiator 13 and the parasitic element 16, having a width in the x-axis direction and extending in the y-axis direction, and being plate-shaped. The reflector 14 has a length longer than the radiator 13 and the parasitic element 16, and the second antenna element 12 has a length shorter than 1 / 4 of the wavelength of the operating frequency. The reflector 14 and the parasitic element 16 and the radiator 13 are spaced apart to allow electromagnetic coupling. The input impedance of the antenna device 10a is broadened by the parasitic element 16, the resistive component of the input impedance of the antenna device 10a is adjusted by the length of the first antenna element 11, and the reactance component of the input impedance of the antenna device 10a is adjusted by the length of the second antenna element 12.

[0043] In this embodiment, the parasitic element 16 is positioned such that, when viewed in the x-axis direction, it overlaps with a part of the first antenna element 11 and overlaps with the entirety of the second antenna element 12. More specifically, when the antenna device 10a is viewed from above, the parasitic element 16 has a plate-shaped first portion 161 extending in the y-axis direction on one side of the first antenna element 11 and the second antenna element 12 in the x-axis direction, a plate-shaped second portion 162 extending in the y-axis direction on the other side of the first antenna element 11 and the second antenna element 12 in the x-axis direction, and a third portion 163 connecting the first portion 161 and the second portion 162.

[0044] With such a powerless element 16, an antenna device 10a is realized that, like the antenna device 9a in the first reference example, has directivity and a structure that can be miniaturized, but with a wider bandwidth than the antenna device 9a in the first reference example.

[0045] (Embodiment 2) Next, an antenna device according to Embodiment 2 of this disclosure will be described.

[0046] Figure 9 is an external view showing the structure of the antenna device 10b according to Embodiment 2. More specifically, Figures 9(a) to (d) are a perspective view, top view, bottom view, and top dimension view of the antenna device 10b, respectively. The antenna device 10b is a modified version of the antenna device 10a according to Embodiment 1, and the shape of the first antenna element 11 is different from that of the antenna device 10a according to Embodiment 1. The differences from Embodiment 1 will be explained below.

[0047] In this embodiment, the first antenna element 11 includes a wide portion 111 having a first width (here, 5 mm) in the x-axis direction and extending in the y-axis direction, and a narrow portion 112 having a second width (here, 2 mm) smaller than the first width in the x-axis direction and extending in the y-axis direction. The wide portion 111 and the narrow portion 112 are connected such that the center of the first width of the wide portion 111 and the center of the second width of the narrow portion 112 are aligned on the same straight line. The combined length of the wide portion 111 and the narrow portion 112 of the first antenna element 11 is 19.5 mm.

[0048] In this embodiment, the first portion 161 and the second portion 162 of the parasitic element 16 are positioned so as to overlap only with the narrow portion 112 of the first antenna element 11 when the parasitic element 16 is viewed in the x-axis direction. In a plan view, the outer edges of the first portion 161 and the second portion 162 of the parasitic element 16 are aligned in a straight line with the outer edge of the wide portion 111 of the first antenna element 11, and there is a gap of 0.5 mm between them and the narrow portion 112 of the first antenna element 11.

[0049] Figure 10 shows the antenna characteristics of the antenna device 10b according to Embodiment 2 shown in Figure 9. More specifically, Figure 10(a) is a Smith chart showing the impedance characteristics of the antenna device 10b according to Embodiment 2, and Figure 10(b) shows the VSWR characteristics of the antenna device 10b according to Embodiment 2.

[0050] As can be seen from Figure 10(a), the antenna device 10b according to Embodiment 2 is resonating at the operating frequency (2.45 GHz).

[0051] Furthermore, as can be seen from Figure 10(b), the antenna device 10b according to Embodiment 2 has a bandwidth of 600 MHz for VSWR ≤ 2, which is wider than the bandwidth of the antenna device 9a according to the base first reference example (420 MHz) and the bandwidth of the antenna device 10a according to Embodiment 1 (580 MHz). This is thought to be because, unlike the antenna device 10a according to Embodiment 1, the first antenna element 11 in the antenna device 10b according to this embodiment has a wide portion 111 (i.e., a wide portion).

[0052] As described above, the antenna device 10b according to this embodiment is a modified version of the antenna device 10a according to Embodiment 1, characterized in that the first antenna element 11 includes a wide portion 111 having a first width in the x-axis direction and extending in the y-axis direction, and a narrow portion 112 having a second width smaller than the first width in the x-axis direction and extending in the y-axis direction, and the first portion 161 and the second portion 162 of the parasitic element 16 are positioned so as to overlap only with the narrow portion 112 of the first antenna element 11 when the parasitic element 16 is viewed in the x-axis direction.

[0053] This results in an even wider bandwidth than the antenna device 9a according to the base first reference example and the antenna device 10a according to Embodiment 1.

[0054] (Embodiment 3) Next, an antenna device according to Embodiment 3 of this disclosure will be described.

[0055] Figure 11 is an external view showing the structure of the antenna device 10c according to Embodiment 3. More specifically, Figures 11(a) to (d) are a perspective view, top view, bottom view, and top dimension view of the antenna device 10c, respectively. The antenna device 10c is based on the antenna device 9b according to the second reference example shown in Figure 5, and is characterized by having a parasitic element 16 arranged on the same plane as the radiator 13.

[0056] The passive element 16 has a fourth portion 164 that overlaps with a part of the first antenna element 11 when viewed in the x-axis direction, and a fifth portion 165 that is connected to the fourth portion 164 and overlaps with at least the entirety of the second antenna element 12.

[0057] Unlike the antenna device 9b according to the second reference example, the first antenna element 11 has a notch 11d that includes a second end 11c on one side 11a, opposite to the first end 11b. The fourth portion 164 of the unpowered element 16 is located within the region of the notch 11d of the first antenna element 11.

[0058] Regarding the specific dimensions, as shown in Figure 11(d), the first antenna element 11 is a rectangle with a length l1 of 23 mm and a width w1 of 5 mm, and has a notch 11d. The second antenna element 12 has a length l2 of 10.5 mm and a width w2 of 1 mm. The unpowered element 16 has a gap of 0.5 mm from the first antenna element 11 and the second antenna element 12, and has an overall length of 25 mm. The width of the fourth part 164 is 1 mm, and of the fifth part 165, the width of the part that overlaps with the entirety of the second antenna element 12 when viewed in the x-axis direction is 3.5 mm, and the length of the part that does not overlap with the second antenna element 12 when viewed in the x-axis direction is 2.5 mm and the width is 5 mm.

[0059] To explain each of these lengths in relation to the wavelength λ (approximately 122 mm, electrical length approximately 57 mm (=122 / √4.6)) at the operating frequency (2.45 GHz), the length l1 of the first antenna element 11 is approximately 0.4 (=23 × √4.6 / 122)λ, the length l2 of the second antenna element 12 is approximately 0.2 (=10.5 × √4.6 / 122)λ, and the length of the unpowered element 16 is approximately 0.4 (=25 × √4.6 / 122)λ.

[0060] Figure 12 shows the antenna characteristics of the antenna device 10c according to Embodiment 3 shown in Figure 11. More specifically, Figure 12(a) is a Smith chart showing the impedance characteristics of the antenna device 10c according to Embodiment 3, and Figure 12(b) shows the VSWR characteristics of the antenna device 10c according to Embodiment 3.

[0061] As can be seen from Figure 12(a), the antenna device 10c according to Embodiment 3 is resonating at the operating frequency (2.45 GHz).

[0062] Furthermore, as can be seen from Figure 12(b), the antenna device 10c according to Embodiment 3 has a bandwidth of 540 MHz for VSWR ≤ 2, which is wider than the bandwidth (420 MHz) of the antenna device 9b according to the base Second Reference Example.

[0063] As described above, the antenna device 10c according to this embodiment is a directional antenna device used in connection with a power supply unit, comprising: a radiator 13 having a plate-shaped first antenna element 11 having a width in the x-axis direction and extending in the y-axis direction, and a second antenna element 12 that is arranged on the same plane as the first antenna element 11, is plate-shaped having a width in the x-axis direction and extending in the y-axis direction, is narrower in width than the first antenna element 11, and has one side 12a connected to one side 11a of the first antenna element 11 via a power supply unit; and a parasitic element 16 arranged on the same plane as the radiator 13 and not connected to the radiator 13, wherein when the parasitic element 16 is viewed in the x-axis direction, it is positioned to overlap with at least a portion of each of the first antenna element 11 and the second antenna element 12. The antenna device 10a comprises a parasitic element 16 positioned on the radiator 13 and the parasitic element 16, a plate-shaped, parasitic reflector 14 positioned on a plane facing the radiator 13 and the parasitic element 16, having a width in the x-axis direction and extending in the y-axis direction, the reflector 14 having a length longer than the radiator 13 and the parasitic element 16, the second antenna element 12 having a length shorter than 1 / 4 of the wavelength of the operating frequency, the reflector 14 and the parasitic element 16 and the radiator 13 are spaced apart to allow electromagnetic coupling, the input impedance of the antenna device 10a is broadbanded by the parasitic element 16, the resistive component of the input impedance of the antenna device 10a is adjusted by the length of the first antenna element 11, and the reactance component of the input impedance of the antenna device 10a is adjusted by the length of the second antenna element 12. The parasitic element 16 is positioned so that, when viewed in the x-axis direction, it overlaps with a part of the first antenna element 11 and overlaps with the entirety of the second antenna element 12.

[0064] In this embodiment, one side 12a of the second antenna element 12 faces the first end 11b of one side 11a of the first antenna element 11, and the parasitic element 16 has a fourth portion 164 that overlaps with a part of the first antenna element 11 when viewed in the x-axis direction, and a fifth portion 165 that is connected to the fourth portion 164 and overlaps with at least the entirety of the second antenna element 12. The first antenna element 11 has a notch 11d that includes the second end 11c of one side 11a opposite to the first end 11b, and the fourth portion 164 of the parasitic element 16 is positioned within the region of the notch 11d of the first antenna element 11.

[0065] This results in a wider bandwidth than that of antenna device 9b in the base second reference example (420 MHz).

[0066] (Embodiment 4) Next, an antenna device according to Embodiment 4 of this disclosure will be described.

[0067] Figure 13 is an external view showing the structure of the antenna device 10d according to Embodiment 4. More specifically, Figures 13(a) to (d) are a perspective view, top view, bottom view, and top dimension view of the antenna device 10d, respectively. The antenna device 10d is a modified version of the antenna device 10c according to Embodiment 3, and the shape of the passive element 16 is different from that of the antenna device 10c according to Embodiment 3. The differences from Embodiment 1 will be explained below.

[0068] In this embodiment, unlike in Embodiment 3, the fifth portion 165 of the parasitic element 16 has the same length in the y-axis direction as the second antenna element 12. In other words, the fifth portion 165 of the parasitic element 16 overlaps the second antenna element 12 without any excess or deficiency when viewed in the x-axis direction.

[0069] Compared to Embodiment 3, the size of the notch 11d formed in the first antenna element 11 is different, but the overall length of the first antenna element 11, the length of the second antenna element 12, and the overall length of the passive element 16 are the same as in Embodiment 3.

[0070] Figure 14 shows the antenna characteristics of the antenna device 10d according to Embodiment 4 shown in Figure 13. More specifically, Figure 14(a) is a Smith chart showing the impedance characteristics of the antenna device 10d according to Embodiment 4, and Figure 14(b) shows the VSWR characteristics of the antenna device 10d according to Embodiment 4.

[0071] As can be seen from Figure 14(a), the antenna device 10d according to Embodiment 4 is resonating at the operating frequency (2.45 GHz).

[0072] Furthermore, as can be seen from Figure 14(b), the antenna device 10d according to Embodiment 4 has a bandwidth of 580 MHz for VSWR ≤ 2, which is wider than the bandwidth of the antenna device 9b according to the base Second Reference Example (420 MHz) and the bandwidth of the antenna device 10c according to Embodiment 3 (540 MHz).

[0073] As described above, the antenna device 10d according to this embodiment is a modified version of the antenna device 10c according to Embodiment 3, characterized in that the fifth portion 165 of the passive element 16 has the same length in the y-axis direction as the second antenna element 12.

[0074] This results in an even wider bandwidth than the antenna device 9b according to the base second reference example and the antenna device 10c according to embodiment 3. Note that the length of the fifth portion 165 in the y-axis direction of the parasitic element 16 may be shorter than that of the second antenna element 12.

[0075] (Embodiment 5) Next, an antenna device according to Embodiment 5 of this disclosure will be described.

[0076] Figure 15 is an external view showing the structure of the antenna device 10e according to Embodiment 5. More specifically, (a1), (a2), (b), (c), and (d) in Figure 15 are a perspective view of the top surface of the antenna device 10e, a perspective view of the bottom surface, a top view, a bottom view, and a bottom view including through holes, respectively. The antenna device 10e corresponds to the antenna device 10d according to Embodiment 4, in which a notch 14a is formed in the reflector plate 14 on the bottom surface.

[0077] The notch 14a formed in the reflector 14 coincides with the "feed point," which is the gap between one side 11a of the first antenna element 11 and one side 12a of the second antenna element 12, when viewed from above, and is connected to the feed point (not shown). This region of the notch 14a makes it possible to feed power to the first antenna element 11 and the second antenna element 12, respectively, from the bottom surface of the substrate 15 of the antenna device 10e (the region of the notch 14a) through the through holes 15a and 15b, as shown in Figure 15(d).

[0078] The dimensions of the notch 14a are 3 mm x 3 mm, and the notch 14a is formed such that it has a 3 mm opening 14b at a position that divides one side of the reflector 14 extending in the y-axis direction into a 29 mm section and a 17 mm section.

[0079] Figure 16 shows the antenna characteristics of the antenna device 10e according to Embodiment 5 shown in Figure 15. More specifically, Figure 16(a) is a Smith chart showing the impedance characteristics of the antenna device 10e according to Embodiment 5, and Figure 16(b) shows the VSWR characteristics of the antenna device 10e according to Embodiment 5.

[0080] As can be seen from Figure 16(a), the antenna device 10e according to Embodiment 5 is resonant at the operating frequency (2.45 GHz). Furthermore, a kink is observed in the impedance characteristics, which is thought to be due to the coupling between the entire reflector 14 and the radiator 13, as well as the coupling between the 29 mm long reflector separated by the notch 14a and the radiator 13.

[0081] Furthermore, as can be seen from Figure 16(b), the antenna device 10e according to Embodiment 5 has a bandwidth of 700 MHz for VSWR ≤ 2, which is wider than the bandwidth of the antenna device 9b according to the base Second Reference Example (420 MHz) and the bandwidth of the antenna device 10d according to Embodiment 4 (580 MHz). This is thought to be due to the effect of a kink that occurred in the impedance characteristics shown in Figure 16(a).

[0082] As described above, the antenna device 10e according to this embodiment is characterized in that a notch 14a is formed in the reflector 14, as a modified part of the antenna device 10d according to Embodiment 4.

[0083] This results in an even wider bandwidth than the antenna device 9b in the base second reference example and the antenna device 10d in embodiment 4.

[0084] In this embodiment, the notch 14a is formed on the reflector 14 at a position that coincides with the feed point in a plan view. However, it is not limited to this position, and may be formed at a position that coincides only with the second antenna element 12 in a plan view, a position that coincides only with the first antenna element 11 in a plan view, or a position where there is an opening on the side of the reflector 14 that is opposite to the side in this embodiment, among the two sides extending in the y-axis direction. Furthermore, the notch 14a is not limited to one location on the reflector 14, but may be formed at two or more locations.

[0085] (Embodiment 6) Next, an antenna device according to Embodiment 6 of this disclosure will be described.

[0086] Figure 17 is an external view showing the structure of the antenna device 10f according to Embodiment 6. More specifically, Figures 17(a) to (d) are a perspective view, top view, bottom view, and top dimension view of the antenna device 10f, respectively. The antenna device 10f is a modified version of the antenna device 10d according to Embodiment 4, and differs from the antenna device 10d according to Embodiment 4 in the shape of the second antenna element 12, etc. The differences from Embodiment 4 will be explained below.

[0087] In this embodiment, unlike in Embodiment 4, the fifth portion 165 of the parasitic element 16 has a shorter length in the y-axis direction than the second antenna element 12. The total length of the parasitic element 16 in the y-axis direction is 24 mm.

[0088] Furthermore, unlike in Embodiment 4, the second antenna element 12 has not only a portion extending in the y-axis direction but also a portion 12b extending in the x-axis direction. This portion 12b extending in the x-axis direction overlaps with the fifth portion 165 of the passive element 16 for 3.5 mm when viewed in the y-axis direction. In other words, the second antenna element 12 has an inverted L shape along two sides of the fifth portion 165 of the passive element 16.

[0089] Figure 18 shows the antenna characteristics of the antenna device 10f according to Embodiment 6 shown in Figure 17. More specifically, Figure 18(a) is a Smith chart showing the impedance characteristics of the antenna device 10f according to Embodiment 6, and Figure 18(b) shows the VSWR characteristics of the antenna device 10f according to Embodiment 6.

[0090] As can be seen from Figure 18(a), the antenna device 10f according to Embodiment 6 is resonating at the operating frequency (2.45 GHz).

[0091] Furthermore, as can be seen from Figure 18(b), the antenna device 10f according to Embodiment 6 has a bandwidth of 620 MHz for VSWR ≤ 2, which is wider than the bandwidth of the antenna device 9b according to the base Second Reference Example (420 MHz) and the bandwidth of the antenna device 10d according to Embodiment 4 (580 MHz).

[0092] As described above, the antenna device 10f according to this embodiment is a modified version of the antenna device 10d according to Embodiment 4, wherein the fifth portion 165 of the passive element 16 has a shorter length in the y-axis direction than the second antenna element 12, and the second antenna element 12 has a portion 12d that extends in the x-axis direction.

[0093] This results in an even wider bandwidth than the antenna device 9b in the base second reference example and the antenna device 10d in embodiment 4.

[0094] The antenna devices relating to this disclosure have been described above based on Embodiments 1 to 6, but this disclosure is not limited to these Embodiments 1 to 6. As long as they do not deviate from the spirit of this disclosure, various modifications to Embodiments 1 to 6 that a person skilled in the art could conceive of, as well as other forms constructed by combining some of the components of Embodiments 1 to 6, are also included within the scope of this disclosure.

[0095] For example, in the antenna devices according to Embodiments 1 to 6, the radiator 13 and the parasitic element 16 are formed on the upper surface of a single substrate 15, and the reflector 14 is formed on the lower surface. However, the device is not limited to such a single substrate configuration. In order to meet the constraint that there is a distance between the radiator 13 and the reflector 14 that allows for electromagnetic coupling, the radiator 13 and the parasitic element 16 may be formed on one of two different substrates, and the reflector 14 may be formed on the other.

[0096] Furthermore, while the antenna device 10e according to Embodiment 5 has a notch 14a formed in the bottom reflector 14 of the antenna device 10d according to Embodiment 4, the antenna devices 10a to 10c and 10f according to Embodiments 1 to 3 and 6 may also have a notch 14a formed in the bottom reflector 14. [Industrial applicability]

[0097] The antenna device described herein is a broadband antenna device with directional properties and a miniaturizable structure, and can be used, for example, as an antenna device for in-vehicle infotainment systems, wearable devices, mobile devices, and the like. [Explanation of Symbols]

[0098] 10a~10f Antenna Equipment 11. First antenna elements 11a One side of the first antenna element 11b The first end of one side of the first antenna element 11c The second end of one side of the first antenna element 11d Notch formed in the first antenna element 111 Wide portion of the first antenna element 112 Narrow portion of the first antenna element 12. Second antenna element 12a One side of the second antenna element 12b The portion of the second antenna element that extends in the x-axis direction 13. Radiator 14 Reflector 14a Notches formed in the reflector 14b Notch opening formed in the reflector 15 circuit boards 15a, 15b Through-hole 16. Unpowered element 161 First part of the unpowered element 162 Second part of the unpowered element 163 Third part of the unpowered element 164 Part 4 of the unpowered element 165 Part 5 of the unpowered element

Claims

1. A directional antenna device used in connection with a power supply unit, A radiator comprising a plate-shaped first antenna element having a width in a first direction and extending in a second direction perpendicular to the first direction, and a second antenna element arranged on the same plane as the first antenna element, having a smaller width than the first antenna element and having one side connected to one side of the first antenna element via the power supply section, A parasitic element positioned on the same plane as the radiator and not connected to the radiator, wherein when the parasitic element is viewed in the first direction, it is positioned to overlap with at least a portion of the first antenna element and the second antenna element, The device comprises a reflector which is a plate-shaped, unpowered reflector, which is arranged in a plane opposite to the radiator and the unpowered element, has a width in the first direction and extends in the second direction, The reflector has a longer length than the radiator, The second antenna element has a length shorter than 1 / 4 of the wavelength of the operating frequency. The radiator and the powerless element and the reflector are spaced apart so that they can be electromagnetically coupled. The resistive component of the input impedance of the antenna device is adjusted by the length of the first antenna element. The reactance component of the input impedance of the antenna device is adjusted by the length of the second antenna element. The passive element is positioned such that, when viewed in the first direction, it overlaps with a portion of the first antenna element and overlaps with the entirety of the second antenna element. Antenna device.

2. The aforementioned powerless element, when viewed in plan, A plate-shaped first portion extending in the second direction on one side in the first direction of the first antenna element and the second antenna element, A plate-shaped second portion extending in the second direction on the other side of the first direction of the first antenna element and the second antenna element, Having a third part connecting the first part and the second part, The antenna device according to claim 1.

3. The first antenna element includes a wide portion having a first width in the first direction and extending in the second direction, and a narrow portion having a second width smaller than the first width in the first direction and extending in the second direction. The first and second portions are positioned such that, when viewed in the first direction, they overlap only with the narrow portion of the first antenna element. The antenna device according to claim 2.

4. The side of the second antenna element faces the first end of the side of the first antenna element, When the powerless element is viewed in the first direction, A fourth portion that overlaps with a part of the first antenna element, It has a fifth portion that is connected to the fourth portion and overlaps with at least the entirety of the second antenna element, The antenna device according to claim 1.

5. The first antenna element has a notch that includes the second end of one side opposite to the first end, The fourth portion is located within the area of ​​the cutout, The antenna device according to claim 4.

6. The fifth portion has the same length in the second direction as the second antenna element. The antenna device according to claim 4.

7. The fifth portion has a length in the second direction that is shorter than that of the second antenna element. The second antenna element has a portion extending in the first direction, The antenna device according to claim 4.

8. The reflector has a notch formed in it. The antenna device according to any one of claims 1 to 7.

Images