Wireless communication device and wireless communication method

Abstract

Provided are a wireless communication device and a wireless communication method capable of improving the directivity of an antenna in a desired direction at low cost. According to one example embodiment, a wireless communication device (1) includes: a printed board (10) having a substrate face (11); a ground plane (20) having a plate shape, the ground plane (20) being disposed on the substrate face (11), connected to a ground potential, and parallel to the substrate face (11); an omnidirectional antenna (30) disposed side by side with the ground plane (20) in one direction on the substrate face (11) in a plane parallel to the substrate face (11), and caused to emit radio waves by being powered; and a parasitic antenna (40) disposed apart from the ground plane (20) in a direction orthogonal to the substrate face (11), and resonating with the powered omnidirectional antenna (30).

Description

TECHNICAL FIELD

[0001] The present application relates to a wireless communication device and a wireless communication method. BACKGROUND

[0002] In recent years, with an increase in wireless communication speed, there has been a demand for wireless communication devices having more advantageous wireless communication characteristics. For example, with respect to such wireless communication devices, there has been an increasing demand for home routers conforming to, for example, a Worldwide Interoperability for Microwave Access (WiMAX) standard or a Long Term Evolution (LTE) standard.

[0003] In order to achieve comfortable wireless communication using an omnidirectional antenna in a home router conforming to such a standard, it is necessary to install the home router as much as possible in a position having a high radio field intensity. In particular, the communication band in the WiMAX standard is in a gigahertz band, which has a high frequency and has a high propagation loss. Therefore, in the case where a home router conforming to the WiMAX standard is installed in the center of a room where radio waves are difficult to reach, or the like, it is sometimes not possible to achieve comfortable wireless communication.

[0004] In order to prevent such a situation, the prior art takes measures so that the home router is installed near a window where radio waves are easily emitted, or as described in Patent Literature 1, a reflection plate for adjusting the directivity of the antenna in a direction where radio waves should reach is attached.

[0005] LIST OF CITATIONS

[0006] PATENT LITERATURE

[0007] [Patent Literature 1] Japanese Patent Application Publication No. 2012-5146

[0008] [Patent Literature 2] International Publication No. WO 2016 / 092801

[0009] [Patent Literature 3] Japanese Patent Application Publication No. 2009-130451 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] Unfortunately, the existing wireless communication devices formed using omnidirectional antennas such as inverted L-shaped antennas have limitations in improvement of radio wave emission characteristics. For example, the possible measures of the home router described above as an example of the existing wireless communication device result in the following problems.

[0012] For example, even if the home router is installed near a window having a large opening, the case where the directivity of the antenna is not adjusted to the outside of the window does not exert a large advantageous effect, and it is not possible to achieve comfortable wireless communication.

[0013] The prior art described in Patent Document 1 and the like requires a reflector that is larger than a home router to provide the directivity of radio waves.

[0014] Furthermore, the use of a reflector as described in the aforementioned Patent Document 1 results in the following disadvantage: the radio waves that communicate between the home router and the subordinate wireless communication terminal (wireless LAN terminal) also have the same directivity as the radio waves in the WiMAX standard or the LTE standard.

[0015] That is, for example, in the case where a home router that conforms to the WiMAX standard is installed near a window, the antenna for WiMAX needs to have the directivity of radio waves toward the outside of the window. In contrast, the wireless LAN antenna for wireless communication with the subordinate wireless communication terminal needs to provide the directivity of radio waves toward the room where the subordinate wireless communication terminal is located (i.e., the inside of the window). Therefore, even if a reflector as described in the aforementioned Patent Document 1 and the like is used, the intended directivity cannot be supported.

[0016] The present application has been made in light of the above-described circumstances, and it is an object of the present application to provide a wireless communication apparatus and a wireless communication method that can improve the directivity of an antenna in a desired direction at low cost.

[0017] Solution to Problem

[0018] A wireless communication apparatus according to one example embodiment includes a printed board having a substrate surface; a ground plane having a plate shape, the ground plane being disposed on the substrate surface, connected to a ground potential, and parallel to the substrate surface; an omnidirectional antenna disposed side by side with the ground plane in one direction on the substrate surface in a plane parallel to the substrate surface, and caused to emit radio waves by being supplied with power; and a parasitic antenna disposed apart from the ground plane in a direction orthogonal to the substrate surface, and resonating with the omnidirectional antenna that has been supplied with power.

[0019] A wireless communication method according to one example embodiment includes the steps of preparing a wireless communication device including a printed board having a substrate face, a ground plane having a plate shape, the ground plane being disposed on the substrate face and parallel to the substrate face, an omnidirectional antenna being disposed side by side with the ground plane in one direction within a plane parallel to the substrate face on the substrate face, and a parasitic antenna being disposed apart from the ground plane in a direction orthogonal to the substrate face; connecting the ground plane to a ground potential; supplying power to the omnidirectional antenna and thus causing the omnidirectional antenna to emit radio waves; causing the parasitic antenna to resonate with the omnidirectional antenna that has been supplied with power; and causing the ground plane to reflect radio waves emitted from the parasitic antenna that has been resonated and emit the reflected radio waves.

[0020] Effects of the Invention

[0021] According to one example embodiment, a wireless communication device and a wireless communication method that can improve the directivity of an antenna in a desired direction at low cost can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a perspective view showing the structure of a wireless communication device without a parasitic antenna according to a first example embodiment;

[0023] Figure 2 is a front view showing the structure of a wireless communication device without a parasitic antenna according to a first example embodiment;

[0024] Figure 3 is a top view showing the structure of a wireless communication device without a parasitic antenna according to a first example embodiment;

[0025] Figure 4 is a perspective view showing a wireless communication device according to a first example embodiment;

[0026] Figure 5 is a front view showing a wireless communication device according to a first example embodiment;

[0027] Figure 6 is a top view showing a wireless communication device according to a first example embodiment;

[0028] Figure 7 is a diagram showing the operation of a wireless communication device according to a first example embodiment;

[0029] Figure 8 is a diagram showing the operation of a wireless communication device according to a first example embodiment;

[0030] Figure 9is a characteristic diagram showing a radiation pattern of a vertical polarized wave on an XY plane in a case where power is supplied to the omnidirectional antenna in the wireless communication device according to the first example embodiment;

[0031] Figure 10 is a characteristic diagram showing a radiation pattern of a vertical polarized wave on an XY plane in a case where power is supplied to the omnidirectional antenna in the wireless communication device according to the first example embodiment;

[0032] Figure 11 is a flowchart showing a wireless communication method using the wireless communication device according to the first example embodiment;

[0033] Figure 12 is a characteristic diagram showing radiation patterns of a vertical polarized wave and a horizontal polarized wave on an XY plane in the wireless communication device according to the first example embodiment;

[0034] Figure 13 is a perspective view showing the wireless communication device according to the second example embodiment;

[0035] Figure 14 is a front view showing the wireless communication device according to the second example embodiment;

[0036] Figure 15 is a top view showing the wireless communication device according to the second example embodiment;

[0037] Figure 16 is a diagram showing an operation of the wireless communication device according to the second example embodiment;

[0038] Figure 17 is a characteristic diagram showing radiation patterns of a vertical polarized wave and a horizontal polarized wave on an XY plane in the wireless communication device according to the second example embodiment;

[0039] Figure 18 is a perspective view showing the wireless communication device according to the third example embodiment;

[0040] Figure 19 is a front view showing the wireless communication device according to the third example embodiment;

[0041] Figure 20 is a top view showing the wireless communication device according to the third example embodiment;

[0042] Figure 21 is a characteristic diagram showing radiation patterns of a vertical polarized wave and a horizontal polarized wave on an XY plane in the wireless communication device according to the third example embodiment;

[0043] Figure 22 is a perspective view showing the wireless communication device according to the fourth example embodiment;

[0044] Figure 23 is a front view showing a wireless communication device according to a fourth example embodiment;

[0045] Figure 24 is a side view showing a wireless communication device according to the fourth example embodiment;

[0046] Figure 25 is a graph showing characteristics of a transmission pattern of a horizontally polarized wave on an XZ plane in a wireless communication device according to the fourth example embodiment;

[0047] Figure 26 is a characteristic graph showing a transmission pattern of a horizontally polarized wave on an XZ plane in a wireless communication device according to the first example embodiment for comparison; and

[0048] Figure 27 is a characteristic graph showing a transmission pattern of a horizontally polarized wave on an XZ plane in a wireless communication device according to the fourth example embodiment. DETAILED DESCRIPTION

[0049] Preferred example embodiments of a wireless communication device and a wireless communication method according to example embodiments are explained below with reference to the accompanying drawings. Note that, for convenience, reference signs assigned to the drawings assigned to the following drawings are assigned to respective elements as an example for facilitating understanding. Of course, the present application is not intended to be limited to the aspects shown.

[0050] (First Example Embodiment)

[0051] A wireless communication device according to the first example embodiment will be explained. First, a structure of the wireless communication device according to the first example embodiment will be explained. After that, an operation of the wireless communication device according to the first example embodiment and a wireless communication method will be explained.

[0052] Figure 1 is a perspective view showing a structure of a wireless communication device without a parasitic antenna according to the first example embodiment. Figure 2 is a front view showing a structure of a wireless communication device without a parasitic antenna according to the first example embodiment. Figure 3 is a top view showing a structure of a wireless communication device without a parasitic antenna according to the first example embodiment. As shown in Figures 1 to 3 the wireless communication device 1 includes a printed board 10, a ground plane 20, and an omnidirectional antenna 30. The wireless communication device 1 transmits or receives radio waves in, for example, a 2.4 GHz band used in Wi-Fi and a 2.6 GHz band used in WiMAX.

[0053] Here, for the convenience of explanation of the wireless communication device 1, XYZ orthogonal coordinate axis systems are introduced. For example, one direction in a plane parallel to one plane of the printed board 10 is referred to as a Z-axis direction. A direction in the plane parallel to the one plane orthogonal to the Z-axis direction is referred to as an X-axis direction. Thus, the plane parallel to the one plane is referred to as an XZ plane. A direction orthogonal to the one plane is referred to as a Y-axis direction. The components of the wireless communication device 1 will be described below.

[0054] <Printed board>

[0055] The printed board 10 having a plate shape or a sheet shape includes one face and another face opposite to the one face. The one face is referred to as a substrate face 11, and the other face is referred to as a back face 12. The printed board 10 includes an insulating material. On the substrate face 11 of the printed board 10, a circuit pattern is formed by, for example, a metal conductor.

[0056] <Ground plane>

[0057] A ground plane 20 is disposed on the substrate face 11 of the printed board 10. The ground plane 20 having a plate shape is parallel to the substrate face 11. The ground plane 20 includes, for example, a metal conductor. When viewed from the Y-axis direction, the ground plane 20 can have, for example, a rectangular shape. An edge of the ground plane 20 on the +Z-axis direction side is an edge extending in the X-axis direction. The ground plane 20 is connected to a ground potential of the wireless communication device 1. The ground plane 20 covers, for example, a portion other than the circuit pattern of the printed board 10.

[0058] <Omni-directional antenna>

[0059] An omni-directional antenna 30 is disposed on the substrate face 11 side of the ground plane 20 in the Z-axis direction. The omni-directional antenna 30 is disposed on the +Z-axis direction side with respect to the ground plane 20. The omni-directional antenna 30 includes, for example, a metal conductor. The omni-directional antenna 30 has, for example, an inverted L shape. Note that the shape of the omni-directional antenna 30 is not limited to the inverted L shape. In a case where radio waves to be transmitted are omni-directional, the omni-directional antenna 30 can have an L shape or an inverted F shape. Further, the omni-directional antenna 30 can be drawn on the substrate face 11 of the printed board 10, or can be disposed using, for example, a chip antenna. Further, a plurality of omni-directional antennas 30 can be disposed on the printed board 10.

[0060] In a case where the omni-directional antenna 30 has an inverted L shape, the omni-directional antenna 30 includes an extension portion 31 extending in the Z-axis direction and an extension portion 32 extending in the X-axis direction. The length of the extension portion 31 extending in the Z-axis direction is greater than the width of the extension portion 31 extending in the X-axis direction. The length of the extension portion 32 extending in the X-axis direction is greater than the width of the extension portion 32 extending in the Z-axis direction. For example, the length of the extension portion 32 extending in the X-axis direction is greater than the length of the extension portion 31 extending in the Z-axis direction.

[0061] One end of the extension portion 31 extending in the Z-axis direction is connected to a power feeding point 33. For example, the end portion of the extension portion 31 on the -Z-axis direction side is connected to the power feeding point 33. The other end of the extension portion 31 extending in the Z-axis direction is connected to one end of the extension portion 32 extending in the X-axis direction. For example, the end portion of the extension portion 31 on the +Z-axis direction side is connected to the end portion of the extension portion 32 on the -X-axis direction side.

[0062] The omni-directional antenna 30 emits radio waves by being supplied with power from the power feeding point 33. The radio waves are, for example, wireless radio waves. The frequency of the radio waves emitted by the omni-directional antenna 30 is, for example, the 2.4 GHz band. However, the frequency of the radio waves emitted by the omni-directional antenna 30 is not limited to the 2.4 GHz band.

[0063] <Parasitic Antenna>

[0064] Figure 4 is a perspective view illustrating a wireless communication device according to the first example embodiment. Figure 5 is a front view illustrating the wireless communication device according to the first example embodiment. Figure 6 is a top view illustrating the wireless communication device according to the first example embodiment.

[0065] As Figures 4 to 6 illustrated, the wireless communication device 1 further includes a parasitic antenna 40. The parasitic antenna 40 has, for example, a plate shape extending in the Z-axis direction. The plate face of the parasitic antenna 40 is parallel to the XZ plane. The parasitic antenna 40 includes, for example, a metal conductor. The parasitic antenna 40 is disposed apart from the ground plane 20 in the Y-axis direction orthogonal to the substrate face 11. For example, in a case where the frequency of the radio waves emitted by the omni-directional antenna 30 is the 2.4 GHz band, the gap between the ground plane 20 and the parasitic antenna 40 is preferably about 5 mm. When the gap is small, and the distance between the ground plane 20 and the parasitic antenna 40 is too small, the radiation characteristic tends to deteriorate. When the gap is large, and the distance between the ground plane 20 and the parasitic antenna 40 is too large, the directivity of the parasitic antenna 40 becomes weak. The gap between the ground plane 20 and the parasitic antenna 40 can be adjusted in accordance with the directivity of the wireless communication device 1.

[0066] The parasitic antenna 40 is formed to resonate with the omnidirectional antenna 30 that has been supplied with power. Specifically, the parasitic antenna 40 extends, for example, in the Z-axis direction. The length of the parasitic antenna 40 that extends in the Z-axis direction is 1 / 2 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30, i.e., λ / 2. Therefore, as a result of the supply of power to the omnidirectional antenna 30, the parasitic antenna 40 is excited when high-frequency current flows through the omnidirectional antenna 30. Therefore, high-frequency current also flows through the parasitic antenna 40. Then, the parasitic antenna 40 emits radio waves.

[0067] The parasitic antenna 40 is disposed near the omnidirectional antenna 30. Therefore, the parasitic antenna 40 can be caused to resonate with the omnidirectional antenna 30 that has been supplied with power. The end portion of the omnidirectional antenna 30 on the side opposite the ground plane 20 in the Z-axis direction and the end portion of the parasitic antenna 40 that extends in the Z-axis direction coincide with each other in the Z-axis direction. Specifically, the end portion of the omnidirectional antenna 30 on the +Z-axis direction side and the end portion of the parasitic antenna 40 on the +Z-axis direction side coincide with each other in the Z-axis direction. Further, the parasitic antenna 40 is parallel to the extension portion 31 of the omnidirectional antenna 30. A portion of the extension portion 32 of the omnidirectional antenna 30 and a portion of the parasitic antenna 40 that includes the end portion of the parasitic antenna 40 on the +Z-axis direction side are opposite each other in the Y-axis direction. In this way, the parasitic antenna 40 is disposed near the omnidirectional antenna 30, and the parasitic antenna 40 is caused to resonate with the omnidirectional antenna 30 that has been supplied with power. Further, the parasitic antenna 40 can be disposed on the end side of the omnidirectional antenna 30, specifically, on a portion of the extension portion 32 on the opposite side of the extension portion 31 (a portion of the extension portion 32 on the +X-axis direction side with respect to the center). Therefore, the parasitic antenna 40 can be more easily caused to resonate with the omnidirectional antenna 30 that has been supplied with power.

[0068] The parasitic antenna 40 is disposed so as to be opposite the substrate face 11 of the printed board 10. Therefore, the radio waves emitted from the parasitic antenna 40 can be reflected on the printed board 10 and the ground plane 20. The strength of the high-frequency current that flows through the parasitic antenna 40 becomes greatest in a central portion of the parasitic antenna 40 that extends in the length direction. Therefore, the strength of the radio waves emitted from the parasitic antenna 40 becomes greatest in this central portion. Therefore, this central portion is caused to be opposite the ground plane 20. Therefore, the radio waves emitted from this central portion can be reflected on the ground plane 20, and the strength of the radio waves emitted toward the +Y-axis direction side can be made great.

[0069] <Operation>

[0070] Next, the operation of the wireless communication device 1 will be described. Figure 7 And Figure 8 is a diagram that shows the operation of the wireless communication device according to the first example embodiment. As shown in FIG. 8, the wireless communication device 1 is caused to perform the following operation. Figure 7As shown, a high-frequency current I1 of a frequency of, for example, 2.4 GHz flows through the omnidirectional antenna 30. Specifically, the high-frequency current I1 is supplied from the power feeding point 33 to the extension portions 31 and 32. Then, an excitation high-frequency current I2 of a frequency of 2.4 GHz also flows through the parasitic antenna 40 disposed near the omnidirectional antenna 30.

[0071] The parasitic antenna 40 has a length of 1 / 2 of a communication wavelength λ of a frequency of 2.4 GHz. Further, the parasitic antenna 40 is disposed near the omnidirectional antenna 30 and in parallel with the extension portion 31. Therefore, the excitation high-frequency current I2 of a frequency of 2.4 GHz flows through the parasitic antenna 40.

[0072] When the high-frequency current I2 flows through the parasitic antenna 40, radio waves are emitted radially around the parasitic antenna 40. That is, radio waves are emitted radially in a direction perpendicular to the Z-axis direction from the parasitic antenna 40 extending in the Z-axis direction. The parasitic antenna 40 is disposed apart from the ground plane 20 on the +Y-axis direction side. Therefore, radio waves emitted from the parasitic antenna 40 toward the -Y-axis direction side are reflected by the ground plane 20 and the printed board 10.

[0073] As shown, Figure 8 the radio waves W1 reflected by the ground plane 20 and the printed board 10 are emitted toward the +Y-axis direction side. Therefore, radio waves having a higher intensity are emitted in the +Y-axis direction. Thus, the radio waves emitted from the parasitic antenna 40 have directivity in the +Y-axis direction. The radio waves emitted from the parasitic antenna 40 are vertically polarized in the XY plane.

[0074] Figure 9 is a characteristic diagram showing an emission pattern of a vertically polarized wave in the XY plane in a case where the omnidirectional antenna is supplied with power in the wireless communication device according to the first example embodiment without the parasitic antenna. Figure 10 is a characteristic diagram showing an emission pattern of a vertically polarized wave in the XY plane in a case where the omnidirectional antenna is supplied with power in the wireless communication device according to the first example embodiment.

[0075] As shown, Figure 9 in a state before the parasitic antenna 40 is implemented, the emission pattern is directed in all directions on the XY plane. The emission pattern has substantially uniform intensity in all directions on the XY plane. In the wireless communication device 1 in the state before the parasitic antenna 40 is implemented, only the omnidirectional antenna 30 emits radio waves. Therefore, the wireless communication device 1 without the parasitic antenna 40 does not have directivity.

[0076] On the other hand, as shown, Figure 10As shown, in the wireless communication device 1 including the parasitic antenna 40, the intensity on the +Y-axis direction side in the XY plane of the emission pattern is large. In a state after the parasitic antenna 40 is implemented, radio waves are emitted not only from the omnidirectional antenna 30 but also from the parasitic antenna 40 excited by the omnidirectional antenna 30. Then, the radio waves emitted from the parasitic antenna 40 are reflected by the ground plane 20 and the printed board 10 toward the +Y-axis direction side. Thus, the wireless communication device 1 has directivity on the +Y-axis direction side.

[0077] (Wireless communication method)

[0078] Next, a wireless communication method using the wireless communication device 1 according to the present example embodiment will be described. Figure 11 is a flowchart showing a wireless communication method using a wireless communication device according to the first example embodiment.

[0079] As shown in step Sll in Figure 11 The wireless communication device 1 is prepared as shown in step Sll. Specifically, the wireless communication device 1 including the printed board 10, the ground plane 20, the omnidirectional antenna 30, and the parasitic antenna 40 is prepared. The printed board 10 includes the substrate face 11. The ground plane 20 having a plate shape is disposed on the substrate face 11 and is parallel to the substrate face 11. The omnidirectional antenna 30 is disposed side by side with the ground plane 20 in the Z-axis direction on the substrate face 11. The parasitic antenna 40 is disposed apart from the ground plane 20 in the +Y-axis direction.

[0080] Next, as shown in step S12, the ground plane 20 is connected to the ground potential. Next, as shown in step S13, the omnidirectional antenna 30 is supplied with power, and caused to emit radio waves. Next, as shown in step S14, the parasitic antenna 40 is caused to resonate with the omnidirectional antenna 30 that has been supplied with power. Then, as shown in step S15, the radio waves emitted from the resonated parasitic antenna 40 are reflected on the ground plane 20 and the printed board 10, and the reflected radio waves are emitted. In this way, wireless communication can be performed using the wireless communication device 1.

[0081] Next, the effects of the present example embodiment will be described.

[0082] The wireless communication device 1 according to the present example embodiment is disposed apart from the ground plane 20, and includes the parasitic antenna 40 that is caused to resonate with the omnidirectional antenna 30 that has been supplied with power. Then, the radio waves excited in the omnidirectional antenna 30 and emitted from the parasitic antenna 40 are reflected on the ground plane 20 and the printed board 10, and emitted toward the +Y-axis direction side. Thus, it is possible to improve the directivity of the antenna in the desired direction.

[0083] The omnidirectional antenna 30 has, for example, an inverted L shape, and the parasitic antenna 40 has, for example, a plate shape extending in one direction, whereby the directivity of the antenna can be improved at low cost.

[0084] By setting the length of the parasitic antenna 40 extending in the Z-axis direction to 1 / 2 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30, the parasitic antenna 40 can be resonated with the omnidirectional antenna 30 that has been powered. Further, the end portion of the omnidirectional antenna 30 on the +Z-axis direction side and the end portion of the parasitic antenna 40 on the +Z-axis direction side coincide with each other in the Z-axis direction, whereby the radio waves emitted from the parasitic antenna 40 can be reflected on the ground plane 20 and the printed board 10. Therefore, the directivity of the antenna can be improved.

[0085] By providing a plurality of omnidirectional antennas 30 and a plurality of parasitic antennas 40 corresponding to the plurality of respective omnidirectional antennas 30, the wireless communication apparatus can comply with various communication standards such as 2 x 2 MIMO (Multiple Input Multiple Output) or the like, for example.

[0086] Further, by arranging each parasitic antenna 40 corresponding to each omnidirectional antenna 30 at different positions (such as the substrate face 11 side or the back face 12 side of the printed board 10 or the like), the wireless communication apparatus 1 can have a plurality of directivities. In the case where a home router complying with the WiMAX standard is installed near a window, the antenna for WiMAX needs to have directivity of radio waves toward the outside of the window. In contrast, the wireless LAN antenna for wireless communication with subordinate wireless communication terminals needs to provide directivity of radio waves toward the room where the subordinate wireless communication terminals are located (i.e., the inside of the window).

[0087] (Second Example Embodiment)

[0088] Next, after explaining the problems of the wireless communication apparatus 1 according to the first example embodiment, the wireless communication apparatus according to the second example embodiment will be explained. Figure 12 is a characteristic diagram showing the emission pattern of the vertical polarized wave and the horizontal polarized wave on the XY plane in the wireless communication apparatus according to the first example embodiment. As shown in Figure 12 As described above with respect to the wireless communication apparatus 1 according to the first example embodiment, the vertical polarized wave has directivity. On the other hand, the horizontal polarized wave does not have sufficient directivity.

[0089] Next, the wireless communication apparatus according to the second example embodiment will be explained. In the wireless communication apparatus according to the present example embodiment, the parasitic antenna is bent in the middle thereof, and generates a high-frequency current in the horizontal direction. Therefore, the horizontal polarized wave also has directivity.

[0090] Figure 13 is a perspective view showing the wireless communication apparatus according to the second example embodiment.Figure 14 is a front view showing a wireless communication device according to a second example embodiment. Figure 15 is a top view showing the wireless communication device according to the second example embodiment.

[0091] As shown in Figures 13 to 15 , the parasitic antenna 40a of the wireless communication device 2 has an inverted L shape when viewed from the Y-axis direction. The parasitic antenna 40a includes an extension portion 41 extending in the Z-axis direction and an extension portion 42 extending in the X-axis direction. One end of the extension portion 41 extending in the Z-axis direction is connected to one end of the extension portion 42 extending in the X-axis direction. Specifically, the end portion of the extension portion 41 on the -Z-axis direction side is connected to the end portion of the extension portion 42 on the -X-axis direction side.

[0092] The length of the extension portion 41 extending in the Z-axis direction is 1 / 2 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30, i.e., λ / 2. The length of the extension portion 42 extending in the X-axis direction is 1 / 2 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30, i.e., λ / 2. Thus, the entire length of the parasitic antenna 40a is λ.

[0093] The parasitic antenna 40a is arranged apart from the ground plane 20 in the Y-axis direction. That is, both the extension portion 41 and the extension portion 42 are arranged apart from the ground plane 20 in the Y-axis direction. The width of the extension portion 41 extending in the X-axis direction is the same as the width of the extension portion 42 extending in the Z-axis direction.

[0094] The end portion of the extension portion 41 in the parasitic antenna 40a extending on the +Z-axis direction side and the end portion of the omnidirectional antenna 30 on the +Z-axis direction side coincide with each other in the Z-axis direction. The central portions of the extension portion 41 and the extension portion 42 are opposite to the ground plane 20 in the Y-axis direction. The other structures of the wireless communication device 2 are the same as those of the wireless communication device 1 according to the above-described first example embodiment.

[0095] Next, the operation of the wireless communication device 2 according to the second example embodiment will be described. Figure 16 is a diagram showing the operation of the wireless communication device according to the second example embodiment. As shown in Figure 16 , for example, a high-frequency current I1 of a frequency of 2.4 GHz flows through the omnidirectional antenna 30. Specifically, the high-frequency current I1 is supplied from the power feeding point 33 to the extension portion 31 and the extension portion 32. Then, an excitation high-frequency current I3 of a frequency of, for example, 2.4 GHz also flows through the parasitic antenna 40a arranged in the vicinity of the omnidirectional antenna 30.

[0096] The entire length of the extension portion 41 and the extension portion 42 of the parasitic antenna 40a is the communication wavelength λ of 2.4 GHz. In addition, the parasitic antenna 40a is arranged near the omnidirectional antenna 30 and in parallel with the extension portion 31 and the extension portion 32. Therefore, the high-frequency current I3 of 2.4 GHz flows through the parasitic antenna 40a. Specifically, for example, the high-frequency current I3 flows from the +Z-axis direction side to the -Z-axis direction side of the extension portion 41 and from the +X-axis direction side to the -X-axis direction side of the extension portion 42.

[0097] When the high-frequency current I3 flows through the parasitic antenna 40a, radio waves are emitted radially around the parasitic antenna 40a. That is, radio waves are emitted radially in a direction perpendicular to the Z-axis direction from the extension portion 41 extending in the Z-axis direction. In addition, radio waves are emitted radially in a direction perpendicular to the X-axis direction from the extension portion 42 extending in the X-axis direction. The parasitic antenna 40a is arranged apart from the ground plane 20 on the +Y-axis direction side. Therefore, radio waves emitted from the parasitic antenna 40a toward the -Y-axis direction side are reflected by the ground plane 20 and the printed board 10.

[0098] Figure 17 is a characteristic diagram showing the emission pattern of the vertical polarized wave and the horizontal polarized wave on the XY plane in the wireless communication device 2 according to the second example embodiment. As shown in Figure 17 the emission pattern of both the vertical polarized wave and the horizontal polarized wave is strong on the +Y-axis direction side on the XY plane. Radio waves emitted from the extension portion 41 and the extension portion 42 of the parasitic antenna 40a are reflected by the ground plane 20 and the printed board 10 toward the +Y-axis direction. Therefore, the wireless communication device 2 has directivity on the +Y-axis direction side for both the vertical polarized wave and the horizontal polarized wave.

[0099] With the wireless communication device 2 according to the present example embodiment, by changing the shape of the parasitic antenna 40a, both the horizontal polarized wave and the vertical polarized wave can have directivity. Therefore, for both the vertical polarized wave and the horizontal polarized wave, emission and reception can be improved.

[0100] In addition, the shape of the parasitic antenna 40a can be changed, for example, by making it have a curved structure. Therefore, directivity can be improved at low cost. In addition, by making it have a curved structure, the degree of freedom of configuration can be improved. Other effects include those described in the description of the first example embodiment.

[0101] (Third Example Embodiment)

[0102] Next, a wireless communication device according to a third example embodiment will be described. The entire length of the parasitic antenna 40a according to the aforementioned second example embodiment is a wavelength λ. On the other hand, the entire length of the parasitic antenna of the wireless communication device according to the present example embodiment is a half wavelength long, i.e., (λ / 2).

[0103] Figure 18 is a perspective view showing a wireless communication device according to a third example embodiment. Figure 19 is a front view showing a wireless communication device according to a third example embodiment. Figure 20 is a top view showing a wireless communication device according to a third example embodiment.

[0104] As shown in Figures 18 to 20 , the parasitic antenna 40b of the wireless communication device 3 has an inverted L shape. The parasitic antenna 40b includes an extension portion 43 extending in the Z-axis direction and an extension portion 44 extending in the X-axis direction. An end portion of the extension portion 43 on the -Z-axis direction side is connected to an end portion of the extension portion 44 on the -X-axis direction side. The length of the extension portion 43 extending in the Z-axis direction is 1 / 4 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30. The length of the extension portion 44 extending in the X-axis direction is 1 / 4 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30. The parasitic antenna 40b is disposed apart from the ground plane 20 in the Y-axis direction orthogonal to the substrate face 11. That is, the extension portion 43 and the extension portion 44 are disposed apart from the ground plane 20 in the Y-axis direction. For example, the width of the extension portion 43 extending in the X-axis direction is the same as the width of the extension portion 44 extending in the Z-axis direction.

[0105] Next, the operation of the wireless communication device 3 according to the third example embodiment will be described. For example, a high-frequency current having a frequency of, for example, 2.4 GHz flows through the omnidirectional antenna 30. Then, an excitation high-frequency current having a frequency of, for example, 2.4 GHz also flows through the parasitic antenna 40b disposed in the vicinity of the omnidirectional antenna 30.

[0106] The entire length of the extension portion 43 and the extension portion 44 of the parasitic antenna 40b is the length of 1 / 2 of the communication wavelength λ of 2.4 GHz. Furthermore, the parasitic antenna 40b is disposed in the vicinity of the omnidirectional antenna 30 and in parallel with the extension portion 31 and the extension portion 32. Therefore, an excitation high-frequency current having a frequency of 2.4 GHz flows through the parasitic antenna 40b.

[0107] When a high-frequency current flows through the parasitic antenna 40b, radio waves are emitted radially around the parasitic antenna 40b. That is, radio waves are emitted radially in a direction perpendicular to the Z-axis direction from the extension portion 43 extending in the Z-axis direction. Further, radio waves are emitted radially in a direction perpendicular to the X-axis direction from the extension portion 44 extending in the X-axis direction. The parasitic antenna 40b is disposed apart from the ground plane 20 on the +Y-axis direction side. Therefore, radio waves emitted from the parasitic antenna 40b toward the -Y-axis direction side are reflected by the ground plane 20 and the printed board 10.

[0108] Figure 21 is a characteristic diagram showing the emission pattern of a vertical polarized wave and a horizontal polarized wave on the XY plane in the wireless communication device according to the third example embodiment. As shown in Figure 21 , the emission pattern of the vertical polarized wave and the horizontal polarized wave is strong on the +Y-axis direction side on the XY plane. Radio waves emitted from the extension portion 43 and the extension portion 44 of the parasitic antenna 40b are reflected by the ground plane 20 and the printed board 10 toward the +Y-axis direction side. Therefore, the wireless communication device 3 has directivity on the +Y-axis direction side for both the vertical polarized wave and the horizontal polarized wave.

[0109] The wireless communication device 3 according to the present example embodiment can reduce the size of the parasitic antenna 40b. Therefore, the size of the wireless communication device 3 can also be reduced. Also in this case, directivity can be improved at low cost. Other structures, operations, and effects are included in the description of the first example embodiment and the second example embodiment.

[0110] (Fourth Example Embodiment)

[0111] Next, the wireless communication device according to the fourth example embodiment will be described. In the foregoing wireless communication device, the parasitic antenna is disposed on the +Y-axis direction side of the ground plane 20 and the omnidirectional antenna 30. On the other hand, in the wireless communication device according to the present example embodiment, the parasitic antenna is disposed on the +Z-axis direction side of the ground plane 20 and the omnidirectional antenna 30.

[0112] Figure 22 is a perspective view showing the wireless communication device according to the fourth example embodiment. Figure 23 is a front view showing the wireless communication device according to the fourth example embodiment. Figure 24 is a side view showing the wireless communication device according to the fourth example embodiment.

[0113] As shown in Figures 22 to 24As shown, the wireless communication device 4 according to the present example embodiment includes, for example, a parasitic antenna 40c having a plate shape extending in the X-axis direction. The parasitic antenna 40c is arranged apart from the omnidirectional antenna 30 on the side opposite the ground plane 20 in the Z-axis direction. Specifically, the parasitic antenna 40 is arranged apart from the omnidirectional antenna 30 on the +Z-axis direction side. The parasitic antenna 40c is formed to resonate with the omnidirectional antenna 30 that has been energized. Specifically, the parasitic antenna 40c is arranged in the vicinity of the omnidirectional antenna 30. The length of the parasitic antenna 40c extending in the X-axis direction is 1 / 2 of the wavelength λ of the radio waves emitted by the omnidirectional antenna 30, i.e., λ / 2.

[0114] The length of the parasitic antenna 40c extending in the X-axis direction is smaller than the length of the ground plane 20 in the X-axis direction. Thus, the radio waves that are reflected on the ground plane 20 and emitted toward the +Z-axis direction side can be made large. Thus, the wireless communication device 1 is able to provide improved directivity.

[0115] Next, the operation of the wireless communication device 4 will be described. Figure 25 is a view showing the operation of a wireless communication device according to a fourth example embodiment. As shown, a high-frequency current I1 having a frequency of, for example, 2.4 GHz flows through the omnidirectional antenna 30. Then, an excitation high-frequency current I4 having a frequency of 2.4 GHz also flows through the parasitic antenna 40c arranged in the vicinity of the omnidirectional antenna 30. Figure 25

[0116] The parasitic antenna 40c has a length of, for example, 1 / 2 of the communication wavelength λ having a frequency of 2.4 GHz. Furthermore, the parasitic antenna 40c is arranged in the vicinity of the omnidirectional antenna 30 and in parallel with the extension portion 32. Thus, the excitation high-frequency current I4 having a frequency of 2.4 GHz flows through the parasitic antenna 40c.

[0117] When the high-frequency current I4 flows through the parasitic antenna 40c, radio waves are emitted radially around the parasitic antenna 40c. That is, radio waves are emitted radially in a direction perpendicular to the X-axis direction from the parasitic antenna 40c extending in the X-axis direction. The parasitic antenna 40c is arranged apart from the ground plane 20 and the printed board 10 on the +Z-axis direction side. Thus, the radio waves emitted from the parasitic antenna 40c on the -Z-axis direction side are reflected by the ground plane 20 and the printed board 10.

[0118] The radio waves W2 reflected by the ground plane 20 and the printed board 10 are emitted toward the +Z-axis direction. Thus, radio waves having a higher intensity are emitted in the +Z-axis direction. Thus, the radio waves emitted from the parasitic antenna 40c have directivity in the +Z-axis direction.

[0119] Figure 26 ​is a characteristic diagram showing a characteristic of a transmission pattern of a horizontally polarized wave on the XZ plane in the wireless communication device according to the first example embodiment for comparison. Figure 27 is a characteristic diagram showing a characteristic of a transmission pattern of a horizontally polarized wave on the XZ plane in the wireless communication device according to the fourth example embodiment.

[0120] As Figure 26 shown, in the wireless communication device 1 according to the first example embodiment, the transmission pattern of the horizontally polarized wave is directed uniformly in all directions on the XZ plane. On the other hand, as Figure 27 shown, in the wireless communication device 4 according to the present example embodiment, the intensity of the transmission pattern of the horizontally polarized wave on the +Z-axis direction side on the XZ plane is large. The radio waves transmitted from the parasitic antenna 40c are reflected by the ground plane 20 and the printed board 10 on the +Z-axis direction side. Therefore, the wireless communication device 4 has directivity on the +Z-axis direction side.

[0121] Based on the wireless communication device 4 according to the present example embodiment, by changing the position of the parasitic antenna 40c, it is possible to change the direction of the directivity. Specifically, the wireless communication device 4 can also have directivity in the Z-axis direction along the board face 11 of the printed board 10. Therefore, it is possible to further improve the degree of freedom of the directivity.

[0122] By configuring the parasitic antenna 40c near the omnidirectional antenna 30 and extending it in the X-axis direction, it is possible to resonate the parasitic antenna 40c with the omnidirectional antenna 30. Further, by setting the length of the parasitic antenna 40c extending in the X-axis direction to 1 / 2 of the wavelength λ of the radio waves transmitted by the omnidirectional antenna 30, it is possible to resonate the parasitic antenna 40c with the omnidirectional antenna 30. Therefore, it is possible to improve the directivity of the wireless communication device 4.

[0123] By setting the length of the parasitic antenna 40c extending in the X-axis direction to be smaller than the length of the ground plane 20 in the X-axis direction, it is possible to transmit a sufficient amount of radio waves transmitted from the parasitic antenna 40c in the +Z-axis direction. Therefore, it is possible to improve the directivity of the wireless communication device 4. Other structures, operations, and effects are included in the descriptions of the first example embodiment to the third example embodiment.

[0124] Note that the present application is not limited to the foregoing example embodiments, and can be appropriately changed without departing from the spirit of the present application. For example, any combination of the structures of the first example embodiment to the fourth example embodiment is included in the technical scope of the first example embodiment to the fourth example embodiment. Further, all or part of the foregoing example embodiments can be described as but are not limited to the following supplementary explanation.

[0125] (Supplementary Explanation 1)

[0126] A wireless communication method, comprising:

[0127] A step of preparing a wireless communication device, the wireless communication device including:

[0128] A printed board having a substrate surface;

[0129] A ground plane having a plate shape, the ground plane being disposed on the substrate surface and being parallel to the substrate surface;

[0130] An omnidirectional antenna being disposed side by side with the ground plane in one direction on the substrate surface in a plane parallel to the substrate surface; and

[0131] A parasitic antenna being disposed apart from the ground plane in a direction orthogonal to the substrate surface;

[0132] A step of connecting the ground plane to a ground potential;

[0133] A step of supplying power to the omnidirectional antenna and thus causing the omnidirectional antenna to emit radio waves;

[0134] A step of causing the parasitic antenna to resonate with the omnidirectional antenna that has been supplied with power; and

[0135] A step of causing the ground plane to reflect radio waves emitted from the parasitic antenna that has been resonated and to emit the reflected radio waves.

[0136] (Supplementary note 2)

[0137] The wireless communication method according to supplementary note 1, wherein

[0138] The omnidirectional antenna having an inverted L shape includes a first extension portion extending in the one direction and a second extension portion extending in another direction orthogonal to the one direction in the plane parallel to the substrate surface,

[0139] The first extension portion has one end connected to a power supply point, and

[0140] The first extension portion has another end connected to one end of the second extension portion extending in the other direction.

[0141] (Supplementary note 3)

[0142] The wireless communication method according to supplementary note 1 or 2, wherein an end portion of the omnidirectional antenna on a side opposite to the ground plane side in the one direction and an end portion of the parasitic antenna in the one direction coincide with each other in the one direction.

[0143] (Supplementary note 4)

[0144] The wireless communication method according to any one of Supplementary notes 1 to 3, wherein

[0145] The parasitic antenna extends in the one direction, and

[0146] A length of the parasitic antenna in the one direction is 1 / 2 of a wavelength of radio waves emitted from the omnidirectional antenna.

[0147] (Supplementary note 5)

[0148] The wireless communication method according to any one of Supplementary notes 1 to 3, wherein

[0149] The parasitic antenna having an inverted L shape includes a third extension portion extending in the one direction, and a fourth extension portion extending in another direction orthogonal to the one direction within a plane parallel to the substrate plane, and

[0150] One end of the third extension portion extending in the one direction is connected to one end of the fourth extension portion extending in the other direction.

[0151] (Supplementary note 6)

[0152] The wireless communication method according to Supplementary note 5, wherein

[0153] A length of the third extension portion extending in the one direction is 1 / 2 of a wavelength of radio waves emitted from the omnidirectional antenna, and

[0154] A length of the fourth extension portion extending in the other direction is 1 / 2 of a wavelength of radio waves emitted from the omnidirectional antenna.

[0155] (Supplementary note 7)

[0156] The wireless communication method according to Supplementary note 5, wherein

[0157] A length of the third extension portion extending in the one direction is 1 / 4 of a wavelength of radio waves emitted from the omnidirectional antenna, and

[0158] A length of the fourth extension portion extending in the other direction is 1 / 4 of a wavelength of radio waves emitted from the omnidirectional antenna.

[0159] (Supplementary note 8)

[0160] The wireless communication method according to any one of Supplementary notes 1 to 7, wherein

[0161] The frequency of the radio wave is a 2.4 GHz band, and

[0162] The gap between the ground plane and the parasitic antenna can be adjusted.

[0163] While the present application has been described with reference to example embodiments, the present application is not limited to the foregoing example embodiments. Various changes which can be understood by those skilled in the art can be made to the configuration and details of the present application within the scope of the present application.

[0164] This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-174873, filed on September 26, 2019, the disclosure of which is incorporated herein in its entirety by reference.

[0165] List of Reference Signs

[0166] 1, 2, 3, 4 wireless communication device

[0167] 10 printed board

[0168] 11 substrate surface

[0169] 12 back surface

[0170] 20 ground plane

[0171] 30 omnidirectional antenna

[0172] 31, 32 extension portion

[0173] 33 power feeding point

[0174] 40, 40a, 40b, 40c parasitic antenna

[0175] 41, 42, 43, 44 extension portion

[0176] I1, I2, I3, I4 current

[0177] W1, W2 radio wave

Claims

1. A wireless communication device, comprising: A printed circuit board having a substrate surface; A grounding plane having a plate shape, the grounding plane being disposed on the substrate surface, connected to a grounding potential, and parallel to the substrate surface; An omnidirectional antenna is arranged side-by-side with the ground plane on the substrate surface in one direction in a plane parallel to the substrate surface, and is configured to transmit radio waves by being powered. as well as A parasitic antenna, which is separately arranged relative to the ground plane in a direction orthogonal to the substrate surface, and resonates with the omnidirectional antenna that has been powered. The parasitic antenna has a plate shape. The surface of the parasitic antenna is parallel to and opposite to the surface of the substrate. Wherein, the end of the omnidirectional antenna on the side opposite to the ground plane in one direction and the end of the parasitic antenna in one direction coincide with each other in one direction.

2. The wireless communication device according to claim 1, wherein, The omnidirectional antenna having an inverted L shape includes: a first extension portion extending in the one direction, and a second extension portion extending in another direction orthogonal to the one direction within a plane parallel to the substrate surface. One end of the first extension portion extending in one direction is connected to a power supply point, and The other end of the first extension portion extending in one direction is connected to the other end of the second extension portion extending in the other direction.

3. The wireless communication device according to claim 1 or 2, wherein, The parasitic antenna extends in the one direction, and The length of the parasitic antenna in one direction is half the wavelength of the radio waves emitted by the omnidirectional antenna.

4. The wireless communication device according to claim 1 or 2, wherein, The parasitic antenna having an inverted L shape includes: a third extension extending in the one direction, and a fourth extension extending in another direction orthogonal to the one direction within a plane parallel to the substrate surface; The end of the third extension portion extending in one direction is connected to the end of the fourth extension portion extending in the other direction.

5. The wireless communication device according to claim 4, wherein, The length of the third extension in the one direction is half the wavelength of the radio wave emitted by the omnidirectional antenna, and The length of the fourth extension in the other direction is half the wavelength of the radio wave emitted by the omnidirectional antenna.

6. The wireless communication device according to claim 4, wherein, The length of the third extension in the one direction is 1 / 4 of the wavelength of the radio wave emitted by the omnidirectional antenna, and The length of the fourth extension in the other direction is 1 / 4 of the wavelength of the radio wave emitted by the omnidirectional antenna.

7. The wireless communication device according to claim 1, wherein, The radio waves are in the 2.4 GHz band, and The gap between the ground plane and the parasitic antenna can be adjusted.

8. A wireless communication device, comprising: A printed circuit board having a substrate surface; A grounding plane having a plate shape, the grounding plane being disposed on the substrate surface, connected to a grounding potential, and parallel to the substrate surface; An omnidirectional antenna is arranged side-by-side with the ground plane on the substrate surface in one direction in a plane parallel to the substrate surface, and is configured to transmit radio waves by being powered. as well as A parasitic antenna, whose side in one direction opposite to the ground plane is separately configured relative to the omnidirectional antenna and resonates with the powered omnidirectional antenna, wherein... The parasitic antenna extends in a plane parallel to the substrate surface in another direction orthogonal to the first direction. The length of the parasitic antenna in the other direction is half the wavelength of the radio wave emitted by the omnidirectional antenna; and The length of the parasitic antenna in the other direction is less than the length of the ground plane in the other direction. The parasitic antenna has a plate shape. The surface of the parasitic antenna is orthogonal to the surface of the substrate and is opposite to the surface of the substrate.

9. The wireless communication device according to claim 8, wherein, The radio waves are in the 2.4 GHz band, and The gap between the ground plane and the parasitic antenna can be adjusted.

10. A wireless communication method, comprising: Prepare a wireless communication device, the wireless communication device comprising: A printed circuit board having a substrate surface; A grounding plane having a plate shape is disposed on the substrate surface and is parallel to the substrate surface; An omnidirectional antenna, which is arranged side-by-side with the ground plane in one direction within a plane parallel to the substrate surface; and Parasitic antennas are arranged separately relative to the ground plane in a direction orthogonal to the substrate surface. The parasitic antenna has a plate shape. The surface of the parasitic antenna is parallel to and opposite to the surface of the substrate. Wherein, the end of the omnidirectional antenna on the side opposite to the ground plane side in one direction and the end of the parasitic antenna in one direction coincide with each other in one direction; Connect the grounding plane to the grounding potential; Power is supplied to the omnidirectional antenna, thereby causing the omnidirectional antenna to transmit radio waves; To make the parasitic antenna resonate with the already powered omnidirectional antenna; and This causes the radio waves emitted from the resonant parasitic antenna to be reflected on the ground plane, and the reflected radio waves to be emitted.

11. The wireless communication method according to claim 10, wherein, The omnidirectional antenna having an inverted L shape includes: a first extension portion extending in the one direction, and a second extension portion extending in another direction orthogonal to the one direction within a plane parallel to the substrate surface. One end of the first extension portion extending in one direction is connected to a power supply point, and The other end of the first extension portion extending in one direction is connected to the other end of the second extension portion extending in the other direction.

12. The wireless communication method according to claim 10 or 11, wherein, The parasitic antenna extends in the one direction, and The length of the parasitic antenna in one direction is half the wavelength of the radio waves emitted by the omnidirectional antenna.

13. The wireless communication method according to claim 10 or 11, wherein, The parasitic antenna having an inverted L shape includes: a third extension extending in the one direction, and a fourth extension extending in another direction orthogonal to the one direction within a plane parallel to the substrate surface; The end of the third extension portion extending in one direction is connected to the end of the fourth extension portion extending in the other direction.

14. The wireless communication method according to claim 13, wherein, The length of the third extension in the one direction is half the wavelength of the radio wave emitted by the omnidirectional antenna, and The length of the fourth extension in the other direction is half the wavelength of the radio wave emitted by the omnidirectional antenna.

15. The wireless communication method according to claim 13, wherein, The length of the third extension in the one direction is 1 / 4 of the wavelength of the radio wave emitted by the omnidirectional antenna, and The length of the fourth extension in the other direction is 1 / 4 of the wavelength of the radio wave emitted by the omnidirectional antenna.

16. The wireless communication method according to claim 10 or 11, wherein, The radio waves are in the 2.4 GHz band, and The gap between the ground plane and the parasitic antenna can be adjusted.

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