Directional antenna device

Abstract

To provide a directional antenna device which is structurally simple, is inexpensive, and is directional.SOLUTION: An antenna device 100 includes: a split ring resonator 103 arranged on a substrate 101; a GND plane 102 formed on the same plane of the substrate 101 as the plane on which the split ring resonator 103 is formed; and a parasitic element 104 separate from the split ring resonator 103 in a direction vertical to the substrate 101, the parasitic element being capable of resonating with a desired frequency. The parasitic element 104 is parallel to the substrate 101 and faces the GND plane 102, and at least a part of a projection surface on which the parasitic element 104 is projected on the substrate 101 in a direction vertical to the substrate 101 is partially overlapped with the split ring resonator 103.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a directional antenna device. [Background technology]

[0002] In recent years, users have been demanding longer communication distances from communication devices. When the communication partner is in a specific direction, a directional antenna can achieve a longer communication distance than an omnidirectional antenna. One example of such a directional antenna is a patch antenna mounted on the device board. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-190756 Summary of the Invention [Problem to be solved by the invention]

[0004] The antenna described in Patent Document 1 requires that a signal from a wireless circuit on the device board be fed to a metal surface on the device board using a pin or the like. Therefore, in devices that require strength, the entire antenna, including the pin, is fixed using a mold or the like, which inevitably results in a problem of high antenna costs. [Means for solving the problem]

[0005] A directional antenna device in one embodiment includes a split ring resonator arranged on a substrate, a GND plane formed on the same surface of the substrate as the split ring resonator, and a parasitic element spaced apart from the split ring resonator in a direction perpendicular to the substrate and capable of resonating at a desired frequency, wherein the parasitic element is parallel to the substrate and faces the GND plane, and at least a portion of a projection plane of the parasitic element projected onto the substrate in a direction perpendicular to the substrate overlaps with the split ring resonator. [Effects of the Invention]

[0006] The directional antenna device of the present disclosure has a simple structure, is inexpensive, and can have directionality. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a perspective view showing a configuration of an antenna device according to a first embodiment. [Figure 2] 1A to 1C are three-view diagrams illustrating a configuration of an antenna device according to a first embodiment. [Figure 3] 4 is an enlarged view showing the direction of a current in the antenna device according to the first embodiment. FIG. [Figure 4] 2 is a cross-sectional view showing an example of radio wave radiation from the antenna device 100 according to the first embodiment. [Figure 5] 10 is a diagram showing the radiation pattern in the YZ plane of an antenna without a parasitic element 104. FIG. [Figure 6] 10 is a diagram showing a radiation pattern in the YZ plane of the antenna device 100 having the parasitic element 104. FIG. [Figure 7] FIG. 10 is a perspective view illustrating an example of an antenna device according to a second embodiment. [Figure 8] 10A and 10B are three-view diagrams illustrating an example of an antenna device according to a second embodiment. [Figure 9] 10 is a diagram illustrating a radiation pattern in the YZ plane of the antenna device according to the second embodiment. FIG. [Figure 10] FIG. 10 is an enlarged view showing the direction of a current in the antenna device according to the second embodiment. [Figure 11] FIG. 10 is a perspective view showing a modified example of the antenna device according to the second embodiment. [Figure 12] 10A and 10B are three-view diagrams illustrating a modified example of the antenna device according to the second embodiment. [Figure 13] FIG. 10 is an enlarged view showing the direction of a current in a modified example of the antenna device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Embodiment 1 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a perspective view showing a configuration of an antenna device according to the first embodiment. Fig. 2 is a three-view diagram showing the configuration of the antenna device according to the first embodiment. In Figs. 1 and 2, an antenna device 100 includes a substrate 101, a GND plane 102, a split ring resonator 103, and a parasitic element 104.

[0009] The substrate 101 is a flat plate-like member made of an electrically insulating material such as resin, etc. Examples of resin include glass cloth and epoxy resin.

[0010] The GND plane 102 is a ground pattern formed on the same surface of the substrate 101 as the split-ring resonator 103. For example, the GND plane 102 is a plate-shaped conductive member made of a conductor such as copper. Specifically, the GND plane 102 is a ground conductor for electric circuits such as a transmission / reception circuit and a signal processing circuit.

[0011] The split ring resonator 103 is connected to a radio circuit (not shown) and is disposed on the substrate 101. For example, the radio circuit may be formed on the rear surface of the substrate 101 (the surface on which the GND plane 102 is not formed).

[0012] Parasitic element 104 is an element that is spaced apart from split ring resonator 103 in a direction perpendicular to substrate 101 and can resonate at a desired frequency. For example, the total length of parasitic element 104 is an integer multiple of a half wavelength of the desired frequency. Specifically, the total length of parasitic element 104 may be a half wavelength of the desired frequency. Alternatively, the total length of parasitic element 104 may be one wavelength of the desired frequency. Parasitic element 104 is parallel to substrate 101 and faces GND plane 102. Parasitic element 104 is a linear element. Parasitic element 104 is formed of a linear or elongated plate-like conductor such as copper, brass, or aluminum.

[0013] The parasitic element 104 is projected onto the substrate 101 in a direction perpendicular to the substrate 101 so that at least a part of the projection plane overlaps with the split ring resonator 103 .

[0014] Next, the operation of the antenna device 100 will be described. FIG. 3 is an enlarged view showing the direction of a current in the antenna device according to the first embodiment. First, when a signal is input to the split ring resonator 103 from a radio circuit (not shown), an antenna current 301 flows at the end of the device substrate. This generates a reverse current 302 in the parasitic element 104. When the current flows through the parasitic element 104, a radio wave is emitted from the parasitic element 104, as shown in FIG. 4. FIG. 4 is a cross-sectional view showing an example of radio wave emission from the antenna device 100 according to the first embodiment. Here, the radio wave emitted toward the substrate 101 is reflected by the GND plane 102 of the substrate 101. As a result, the radio wave toward the parasitic element 104 becomes stronger, and the radio wave toward the opposite side becomes weaker. As a result, a directional antenna is obtained.

[0015] Next, the directivity of the antenna will be described. Fig. 5 is a diagram showing the radiation pattern in the YZ plane of an antenna without parasitic element 104. Fig. 6 is a diagram showing the radiation pattern in the YZ plane of antenna device 100 with parasitic element 104. As shown in Fig. 6, antenna device 100 has a characteristic with directivity in the -Y direction, so it can be seen that adding parasitic element 104 has changed it into a directional antenna.

[0016] As described above, according to the antenna device of the first embodiment, a directional antenna can be realized at low cost by adding a simple parasitic element 104. Furthermore, according to the antenna device of the first embodiment, the communication distance can be increased by orienting this directional antenna in the direction of the incoming radio waves.

[0017] Embodiment 2 In the second embodiment, an antenna device that provides directivity to horizontally polarized wave components will be described.

[0018] In the first embodiment, by adding the shape of parasitic element 104, it is possible to impart directivity to vertically polarized waves in the -Y direction, but sufficient directivity cannot be achieved for the horizontally polarized wave component. This is because there is almost no high-frequency current in the horizontal direction in parasitic element 104. To solve this problem, in the second embodiment, parasitic element 104 is bent midway.

[0019] Fig. 7 is a perspective view showing an example of an antenna device according to a second embodiment. Fig. 8 is a three-view diagram showing an example of an antenna device according to the second embodiment. In Fig. 7, an antenna device 700 includes a substrate 101, a GND plane 102, a split ring resonator 103, and a parasitic element 704. In Figs. 7 and 8, the same components as those in Figs. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

[0020] The parasitic element 704 is an element that is spaced apart from the split ring resonator 103 in a direction perpendicular to the substrate 101 and can resonate at a desired frequency. The parasitic element 704 is parallel to the substrate 101 and faces the GND plane 102. For example, the total length of the parasitic element 704 is an integer multiple of a half wavelength of the desired frequency. Specifically, the total length of the parasitic element 704 may be one wavelength of the desired frequency. The parasitic element 704 is parallel to the substrate 101 and faces the GND plane 102.

[0021] Parasitic element 704 has first linear element 711 and second linear element 712 connected at the end. First linear element 711 and second linear element 712 form a predetermined angle. When imparting directivity to the vertical polarization component and the horizontal polarization component, it is desirable that first linear element 711 and second linear element 712 be orthogonal to each other.

[0022] Next, the directivity of the antenna will be described. Fig. 9 is a diagram showing the radiation pattern in the YZ plane of the antenna device according to the second embodiment. As shown in Fig. 9, in the antenna device 700, a horizontally polarized wave in the -Y direction is generated. The current flowing through the parasitic element 704 at this time is as shown in Fig. 10. Fig. 10 is an enlarged view showing the direction of the current in the antenna device according to the second embodiment.

[0023] As described above, according to the antenna device of the second embodiment, by forming parasitic element 104 in a shape that is bent midway, an antenna having directivity for both horizontally and vertically polarized waves can be realized.

[0024] The present disclosure is not limited to the above-described embodiments, and modifications can be made as appropriate without departing from the spirit of the present disclosure. For example, in the second embodiment, the total length of parasitic element 704 is one wavelength, but the total length may be half a wavelength. Fig. 11 is a perspective view showing a modified example of the antenna device according to the second embodiment. Fig. 12 is a three-view diagram showing a modified example of the antenna device according to the second embodiment. Fig. 13 is an enlarged view showing the direction of current in the modified example of the antenna device according to the second embodiment.

[0025] However, in the example of Figure 11, the band in which parasitic element 704 is effective tends to be narrower than in Figure 7. This is because the current generated in parasitic element 104 as shown in Figure 1 is reduced by bending it. However, this is a technology that can be used sufficiently when the band in use is narrow. The modification of embodiment 2 makes it possible to realize an antenna that has directivity for both horizontally and vertically polarized waves even when parasitic element 704 is made smaller. [Explanation of symbols]

[0026] 100, 700 antenna equipment 101 Substrate 102 GND plane 103 Split-ring resonator 104, 704 parasitic elements 711 First linear element 712 Second linear element

Claims

1. a split ring resonator disposed on a substrate; a GND plane formed on the same surface as the split ring resonator on the substrate; a parasitic element that is spaced apart from the split ring resonator in a direction perpendicular to the substrate and that can resonate at a desired frequency; the parasitic element is parallel to the substrate and faces the GND plane so as to be able to reflect radio waves radiated from the parasitic element; A directional antenna device arranged so that the center of the parasitic element and the center of the split ring resonator are aligned.

2. 2. The directional antenna device according to claim 1, wherein the parasitic element is a linear element.

3. 2. The directional antenna device according to claim 1, wherein the parasitic element comprises a first linear element and a second linear element connected at an end thereof.

4. 4. The directional antenna device according to claim 3, wherein the first linear element and the second linear element are orthogonal to each other.

5. 5. The directional antenna device according to claim 2, wherein the total length of the parasitic element is an integer multiple of a desired frequency.

6. 6. The directional antenna device according to claim 5, wherein the total length of the parasitic element is half the wavelength of a desired frequency.

7. 6. The directional antenna device according to claim 5, wherein the total length of the parasitic element is one wavelength of a desired frequency.

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