JP-7854918-B2 - Antenna equipment

JP7854918B2JP 7854918 B2JP7854918 B2JP 7854918B2JP-7854918-B2

Inventors

小島優

Assignees

パナソニック株式会社

Dates

Publication Date: 20260507
Application Date: 20221026

Claims (8)

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 that is unpowered, 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, and is plate-shaped. 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.
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 .
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 .
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 .
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 .
The fifth portion has the same length in the second direction as the second antenna element. The antenna device according to claim 4 .
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 .
The reflector has a notch formed in it. The antenna device according to any one of claims 1 to 7 .

Description

This disclosure relates to an antenna device, and more particularly to an antenna device having a directional and miniaturizable structure. In recent years, the adoption of IoT (Internet of Things) devices has been rapidly increasing worldwide. Antennas for IoT devices require miniaturization from the perspectives of design and portability. Furthermore, since the performance of the antenna is degraded by the presence of human bodies or metal objects nearby, it is necessary for the antenna to be robust against surrounding objects. To reduce the influence of surrounding metal objects, a unidirectional antenna is effective. Therefore, it is desirable for IoT device antennas to be small and unidirectional. Therefore, conventionally, antenna devices have been proposed that feature a miniaturized structure with an unpowered reflector facing the radiator, and where electromagnetic coupling between the radiator and the reflector enhances directivity toward the side opposite the reflector (see, for example, Patent Document 1). International Publication No. 2018/198349 Figure 1 is an external view showing the structure of the antenna device according to the first reference example.Figure 2 shows the antenna characteristics of the antenna device according to the first reference example.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 is a Smith chart showing the impedance characteristics when the length of the second antenna element is changed by 1 mm increments in the antenna device according to the first reference example.Figure 5 is an external view showing the structure of the antenna device according to the second reference example.Figure 6 shows the antenna characteristics of the antenna device according to the second reference example.Figure 7 is an external view showing the structure of the antenna device according to Embodiment 1.Figure 8 shows the antenna characteristics of the antenna device according to Embodiment 1.Figure 9 is an external view showing the structure of the antenna device according to Embodiment 2.Figure 10 shows the antenna characteristics of the antenna device according to Embodiment 2.Figure 11 is an external view showing the structure of the antenna device according to Embodiment 3.Figure 12 shows the antenna characteristics of the antenna device according to Embodiment 3.Figure 13 is an external view showing the structure of the antenna device according to Embodiment 4.Figure 14 shows the antenna characteristics of the antenna device according to Embodiment 4.Figure 15 is an external view showing the structure of the antenna device according to Embodiment 5.Figure 16 shows the antenna characteristics of the antenna device according to Embodiment 5.Figure 17 is an external view showing the structure of the antenna device according to Embodiment 6.Figure 18 shows the antenna characteristics of the antenna device according to Embodiment 6. (Antenna device as an example) Before describing embodiments of this disclosure, two examples of antenna devices for the 2.4 GHz band (with a roughly center frequency of 2.45 GHz and a wavelength of approximately 122 mm) based on the technology described in Patent Document 1 will be described as reference examples of antenna devices. (First reference example) Figure 1 is an external view showing the structure of the antenna device 9a according to the first reference example. More specifically, Figures 1(a) to (f) are a perspective view, top view, bottom view, side view, top dimension view, and bottom dimension view of the antenna device 9a, respectively. The antenna device 9a is a long, rectangular shape as a whole. The width direction is defined as the x-axis (also called the "first direction"), the direction perpendicular to the x-axis and extending along the length is defined as the y-axis (also called the "second direction"), and the direction perpendicular to both the x-axis and the y-axis is defined as the z-axis. The antenna device 9a is a directional antenna used in connection with a feed unit (not shown), and comprises a radiator 13 having a first antenna element 11 which is plate-shaped with width in the x-axis direction and extending in the y-axis direction, and a second antenna element 12 which is plate-shaped with width in the x-axis direction and extending in the y-axis direction, but is narrower than the first antenna element 11, and has one side 12a connected to one side 11a of the first antenna element 11 via a feed unit, and a non-powered reflector 14 which is plate-shaped with width in the x-axis direction and extending in the y-axis direction, and is arranged in a plane opposite to the radiator 13. The second antenna element 12 may be inverted L-shaped, and its shape is not limited to a straight shape. Here, the reflector 14 has a length longer than the radiator 13, the seco