Receiving antenna

Abstract

The present invention provides a receiving antenna that can efficiently receive power transmitted from a power transmitter located at a certain distance, and that can tolerate a certain range in size. [Solution] A receiving antenna used for wireless power transmission, comprising: a first conductive plate; a second conductive plate facing the first conductive plate; a feeder connecting the first end of the first conductive plate and the second end of the second conductive plate facing the first end; and a conductive member connecting the first other end opposite to the first end and the second other end opposite to the second end.

Description

Technical Field

[0001] [Related Application] This application claims the priority of International Patent Application No. PCT / JP2021 / 039559 titled "Power Receiving Antenna" filed on October 26, 2021, the disclosure of which is incorporated herein by reference in its entirety. This disclosure relates to a power receiving antenna for receiving power by wireless power supply.

Background Art

[0002] In recent years, wireless power supply has been carried out, enabling charging and operation of various electronic devices. Patent Documents 1 and 2 disclose the configuration of a power receiving antenna for wireless power supply.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, various IoT devices have been developed and put into use, and many of these IoT devices include those used as various types of sensor devices. While long operating times are desirable for such sensor devices, battery operation has time limitations. These sensor devices do not actually require much power to operate, and can operate sufficiently with power supplied by wireless power transfer. Nevertheless, it is desirable to be able to efficiently receive the transmitted power, and the development of an efficient receiving antenna is desired. Furthermore, sensors and the like are required to be able to receive power and operate even when power is transmitted from a distant location. The receiving antenna described in Patent Document 1 has the problem that the transmitting side must be located in a nearby location. In addition, since the receiving antenna is used mounted on various devices, there is also the problem that it needs to be able to adapt to various shapes.

[0005] Therefore, the present disclosure aims to provide a receiving antenna that can efficiently receive power transmitted from a power transmitter located at a certain distance and that can tolerate a certain range in size. [Means for solving the problem]

[0006] To solve the above problems, for example, the configuration described in the claims may be adopted. The present invention includes several means for solving the above-mentioned problems, but to give one example, the receiving antenna comprises a first conductive plate, a second conductive plate facing the first conductive plate, a feeder connecting the first end of the first conductive plate and the second end of the second conductive plate facing the first end, and a conductive member connecting the first other end opposite to the first end and the second other end opposite to the second end.

[0007] In the above-described power receiving antenna, the conductive member may be a plate-shaped member that connects the first other end of the first conductive plate and the second other end of the second conductive plate.

[0008] In the above-described power receiving antenna, the first conductive plate, the second conductive plate, and the plate-shaped conductive member may be integrally molded.

[0009] In the above-described power receiving antenna, the first conductive plate, the second conductive plate, and the plate-shaped conductive member may be composed of a single conductive plate that has been bent.

[0010] In the above-described receiving antenna, a single conductive plate may be constructed with a cutout extending a predetermined distance from its end.

[0011] In the above-described power receiving antenna, the first conductive plate may have a stepped central portion in the longitudinal direction that protrudes toward the second conductive plate, and the second conductive plate may have a stepped central portion in the longitudinal direction that protrudes toward the first conductive plate.

[0012] In the above-described receiving antenna, the plate-shaped conductive plate may be configured with a cutout within a predetermined distance from its end.

[0013] In the above-described power receiving antenna, slots may be provided in the first conductive plate and the second conductive plate.

[0014] In the above-described power receiving antenna, a projection may be provided in which a part of the first conductive plate protrudes from the widthwise end of the first conductive plate near the center toward the second conductive plate.

[0015] In the above-described receiving antenna, a gap may be provided between the tip of the protruding portion and the second conductive plate. [Effects of the Invention]

[0016] A receiving antenna used in wireless power transmission according to one aspect of the present invention can efficiently receive power due to its shape and supply power to the device to which the receiving antenna is connected. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a diagram showing a configuration example of an antenna according to the present invention. [Figure 2] Figure 2 is an example of a graph showing the transition of radiation efficiency according to the communication frequency of the antenna shown in Figure 1. [Figure 3] Figure 3 is an example of a graph showing the transition of S parameters according to the communication frequency of the antenna shown in Figure 1. [Figure 4] Figure 4 is an example of a graph showing the transition of radiation efficiency according to the communication frequency when the substrate size of the antenna shown in Figure 1 is changed. [Figure 5] Figure 5 is an example of a graph showing the transition of radiation efficiency according to the communication frequency of an antenna having a size different from that of the antenna shown in Figure 1. [Figure 6] Figure 6 is an example of a graph showing the transition of S parameters according to the communication frequency of an antenna having a size different from that of the antenna shown in Figure 1. [Figure 7] Figure 7 is an example of a graph showing the transition of each S parameter according to the communication frequency of an antenna having a size different from that of the antenna shown in Figure 1. [Figure 8] Figure 8 is an example of a graph showing the transition of each S parameter in the vertical direction according to the communication frequency of an antenna having a size different from that of the antenna shown in Figure 1. [Figure 9] Figure 9 is an example of a graph showing the transition of radiation efficiency according to the communication frequency of an antenna having a size different from that of the antenna shown in Figure 1. [Figure 10] Figure 10 is an example of a graph showing the relationship between the size in the planar direction of the antenna and the radiation efficiency. [Figure 11] Figure 11 is an example of a diagram showing a configuration example of an antenna having a configuration different from that of Figure 1. [Figure 12] The upper diagram of Figure 12 is an example of a graph showing the transition of radiation efficiency according to the communication frequency when the height of the antenna is changed. The lower diagram of Figure 12 is an example of a graph showing the transition of radiation efficiency according to the communication frequency when the width of the antenna is changed. [Figure 13]Figure 13 is an example of a diagram showing the antenna pattern (directivity) when the antenna height is changed. [Figure 14] Figures 14(a) to (f) are examples of diagrams showing various antenna configurations. [Figure 15] Figure 15 shows an example of the antenna shown in Figure 14(f) and a magnified view of a part thereof. [Figure 16] Figure 16 is an example of a graph showing the change in radiation efficiency according to the communication frequency of each antenna shown in Figure 14. [Figure 17] Figure 17 is an example of a diagram showing the antenna pattern (directivity) of each antenna shown in Figure 14. [Figure 18] Figure 18 is an example of a diagram showing that the antenna shown in Figure 14(f) functions as a composite antenna. [Figure 19] Figure 19 is an example of a graph showing the radiation efficiency of the antenna according to the communication frequency when the gap between the antenna protrusion shown in Figure 14(f) and the second conductive plate is changed. [Figure 20] Figure 20 is an example of a diagram showing the antenna pattern (directivity) of an antenna when the gap between the antenna protrusion shown in Figure 14(f) and the second conductive plate is changed. [Figure 21] Figure 21 is an example diagram showing a configuration when the antenna is configured in a spherical shape. [Figure 22] Figure 22 is an example of a graph showing the radiation efficiency of the antenna shown in Figure 21 according to the communication frequency. [Figure 23] Figure 23 is an example of a diagram showing the antenna pattern (directivity) of the antenna shown in Figure 21. [Figure 24] Figure 24 is an example diagram showing a configuration when the antenna is configured in a columnar shape. [Figure 25] Figure 25 is an example of a graph showing the radiation efficiency of the antenna shown in Figure 24 according to the communication frequency. [Figure 26] Figure 26 is an example of a diagram showing the antenna pattern (directivity) of the antenna shown in Figure 24. [Figure 27]Figure 27 is an example diagram showing an antenna configuration when a power receiving circuit is provided on one side of the conductive plate. [Figure 28] Figure 28 is an example of a graph showing the radiation efficiency of the antenna shown in Figure 27 according to the communication frequency. [Figure 29] Figure 29 is an example of a diagram showing the antenna pattern (directivity) of the antenna shown in Figure 27. [Figure 30] Figure 30 is an example of a diagram showing one application of the antenna according to this embodiment. [Figure 31] Figure 31 is an example of an unfolded perspective view of the package shown in Figure 30. [Figure 32] Figure 32 is an example of a diagram showing the basic configuration of the antenna according to Example 2 and the core material that can be applied thereto. [Figure 33] Figure 33 is an example of a diagram showing the cross-sectional configuration of the first conductive plate in Figure 32(B). [Figure 34] Figure 34 shows an example of antenna implementation according to Example 2. [Figure 35] Figure 35 shows an example of an antenna modification and an example of a diagram illustrating the core material that can be applied thereto. [Figure 36] Figure 36 is an example of a diagram showing a modification to the antenna for 2.4GHz. [Figure 37] Figure 37 is an example of a diagram showing an implementation example in which power is supplied to a sensor using the antenna according to Example 2. [Figure 38] Figure 38 is an example of a diagram showing the simulation results of the radio wave efficiency of two antennas. [Figure 39] Figure 39 is an example diagram showing an implementation where an antenna is used to supply power to sensors placed on a device. [Figure 40] Figure 40 is an example of a figure showing the simulation results of the received signal strength of two antennas. [Figure 41] Figure 41 is an example of a diagram illustrating a conceptual model for efficiently manufacturing multiple antennas. [Figure 42] Figure 42 is an example of a graph showing the change in impedance (Z parameter) of the antenna shown in Figure 1 according to the communication frequency. [Figure 43] Figure 43 is an example of a figure showing the simulation results of the antenna's electric field. [Figure 44] Figure 44 is an example of a diagram illustrating a conceptual relationship between frequency and impedance. [Modes for carrying out the invention]

[0018] The receiving antenna for wireless power transfer (wireless power transfer) according to this embodiment will be described below with reference to the drawings.

[0019] (Example 1) As shown in Figure 1, the antenna 1 according to this embodiment is an antenna used in a receiving device for wireless power transmission, comprising a long plate-shaped first conductive plate 10a and a long plate-shaped second conductive plate 10b facing each other, connected at one end via a feeder 11 (rectifier) ​​and also connected by a conductive member 10c (shorting pin). The antenna 1 is an antenna used in the 920 megahertz band for wireless power transmission, but the communication band used is not limited to the 920 megahertz band, and may be 2.4 gigahertz or 5.7 gigahertz. In this specification, the communication band used will be described as the 920 megahertz band.

[0020] Antenna 1 is a receiving antenna for long-distance wireless power transmission, receiving and supplying power for the operation of various IoT devices. Therefore, Antenna 1 may be mounted on or connected to various devices, and it is desirable that it be able to accommodate a wide range of shapes and sizes. Furthermore, in the case of Antenna 1, the antenna is inductive, and by making the feeder 11 (rectifier) ​​capacitive, matching can be achieved without an impedance matching circuit that has losses, thus functioning as a highly efficient receiving antenna system. The first conductive plate 10a and the second conductive plate 10b are both flat, thin plates with length L1 and width W1. Figure 1 shows an example where width W1 = 15 mm, length L1 = 40 mm, and distance H1 = 10 mm between the thin plates.

[0021] Furthermore, although Figure 1 shows an example of the conductive member 10c being rod-shaped, it is not limited to a rod shape as long as the first conductive plate 10a and the second conductive plate 10b can be connected; it may also be plate-shaped. The first conductive plate 10a, the second conductive plate 10b, and the conductive member 10c can be made of any material that conducts current well, such as copper or aluminum.

[0022] The feeder 11 is a so-called power supply line and is provided at one end of the antenna 1 to connect the first conductive plate 10a and the second conductive plate 10b. That is, the feeder 11 is connected to the end of the first conductive plate 10a and to the end of the second conductive plate 10b that is opposite to the first conductive plate 10a. In Figure 1, an example is shown in which the conductive member 10c is provided near the feeder 11, but it is preferable that this conductive member 10c be provided at the end opposite to the end to which the feeder 11 is provided. The opposite end here refers to the end of the first conductive plate 10a and the second conductive plate 10b that is opposite in the longitudinal direction when viewed from the ends of the first conductive plate 10a and the second conductive plate 10b to which the feeder 11 is connected. The reason for this will be explained below using Figures 2 and 3.

[0023] Figure 2 shows the radiation efficiency of antenna 1 when the conductive member 10c is positioned at various locations, and shows the radiation efficiency at each frequency. Figure 3 shows the change in the S-parameters of antenna 1 at each frequency. Antenna 1 is an antenna used as a receiving antenna in wireless power transmission, and its radiation efficiency is an indicator of how efficiently the power radiated from the radiation source can be received as power.

[0024] The data shown in Figures 2 and 3 represent the results of simulations performed for antenna 1, where W1=30mm, L1=60mm, and H1=10mm, and the position of the conductive member 10c is varied by changing the distance d from the center of the antenna 1 in the longitudinal direction. The distance d is defined as the positive direction towards the feeder 11, and the results are shown for simulations performed for d=-30, d=-23.3333, d=-16.6667, d=-10, d=-3.3333, d=3.3333, d=10, and d=16.6667. d=0 is the center position in the longitudinal direction of antenna 1, and d=-30 is the position of the end of the first conductive plate 10a (second conductive plate 10b) on the opposite side from where the feeder 11 is located.

[0025] Figure 2 shows that the radiation efficiency of antenna 1 does not depend significantly on the position of the conductive member 10c in the 920 megahertz band. Figure 2 shows the communication frequency on the horizontal axis and the radiation efficiency on the vertical axis. Specifically, in the 920 megahertz band, the radiation efficiency when d=-30 is 0.92492264, when d=-23.3333 is 0.91848839, when d=-16.6667 is 0.90653664, when d=-10 is 0.89302688, when d=-3.3333 is 0.88013362, when d=3.3333 is 0.8730083, when d=10 is 0.87878139, and when d=16.6667 is 0.9007059. Thus, in all cases, it can be understood that a radiation efficiency of 0.85 or higher can be guaranteed in the 920 megahertz band.

[0026] Furthermore, except for the case where d = 23.3333, the radiation efficiency of the antenna 1 is higher when the conductive member 10c is moved further away from the feeder 11. These values ​​were obtained by the applicants through simulation. Among these values, it can be seen that the radiation efficiency when d = -30, i.e., when the conductive member 10c is placed on the opposite side of the feeder 11, is relatively high among the simulated arrangements. As can be seen from Figure 2, it is preferable that the conductive member 10c is provided so as to connect the first conductive plate 10a and the second conductive plate 10b at the end opposite to the end of the first conductive plate 10a and the second conductive plate 10b on which the feeder 11 is provided, in the longitudinal direction.

[0027] Figure 3 is a graph showing the changes in the S-parameters, or more precisely, the S11 parameters, of antenna 1 for each frequency band according to the position of the conductive member 10c from the center. In the graph of Figure 3, the horizontal axis shows the communication frequency, and the vertical axis shows the decibel value. S11 is the input reflection coefficient for antenna 1. However, less reflection is preferable for efficiency, and a lower decibel value is preferable. However, in the example of Figure 3, the reflection coefficient is simulated for 50 ohms, and since the actual value differs from that when matching directly with the circuit side, it is not 50 ohms. As the conductive member 10c is brought closer to the feeder 11, the S-parameters drop in the 920 megahertz band, so it is preferable to position the conductive member 10c as far away from the feeder 11 as possible.

[0028] In Figure 3, the S-parameter values ​​in the 920 megahertz band corresponding to each placement position of the conductive member 10c are d = -30, that is, the S11 parameter (sometimes simply referred to as S11) when the conductive member 10c is placed at the position furthest from the feeder 11 is -0.11598898. Similarly, the applicants obtained through simulations that S11 = -0.12124553 when d = -23.3333, S11 = -0.13121938 when d = -16.6667, S11 = -0.14794466 when d = -3.3333, S11 = -0.17484571 when d = 3.3333, S11 = -0.21969521 when d = 10, S11 = -0.302915 when d = 16.6667, and S11 = -0.50750559 when d = 16.6667.

[0029] From this value, it can be understood that setting d=16.6667 is preferable for antenna 1 in terms of reflectivity. However, in terms of antenna pattern (antenna directivity), placing the conductive member 10c at a position away from the feeder 11 makes it closer to omnidirectional. Considering that it is desirable for a receiving antenna to be able to receive power regardless of its position relative to the transmitter, it is best for the antenna pattern to be omnidirectional. Combined with radiation efficiency, it is preferable that d=-30, that is, that the conductive member 10c is provided so as to connect the first conductive plate 10a and the second conductive plate 10b at opposite ends in the longitudinal direction from the ends of the first conductive plate 10a and the second conductive plate 10b where the feeder 11 is provided.

[0030] Based on the parameters shown in Figures 2 and 3, as well as the antenna pattern and usage scenarios of the antenna 1, it is preferable that the conductive member 10c connects the first conductive plate 10a and the second conductive plate 10b at opposite ends in the longitudinal direction of the feeder 11. Therefore, it is preferable that the antenna 1 be configured such that the first conductive plate 10a and the second conductive plate 10b facing the first conductive plate 10a are connected at a predetermined distance apart, with one end connected by the feeder 11 and the other end connected by the conductive member 10c.

[0031] Figure 4 shows the changes in the S-parameters of antenna 1 when the combinations of W1 and L1 are (W1,L1)=(30mm,60mm), (W1,L1)=(60mm,120mm), and (W1,L1)=(120mm,240mm). Note that the example in Figure 4 was measured with a distance of 1m from the power source to antenna 1.

[0032] As shown in Figure 4, when using the 920 megahertz band as the frequency for power supply, the best S-parameters (highest received level (decibels)) were observed when (W1,L1)=(30mm,60mm), followed by (W1,L1)=(120mm,240mm), and the lowest was observed when (W1,L1)=(60mm,120mm). However, the actual differences in these values ​​were not significant, and all values ​​were considered to be practical. Therefore, considering that in any device requiring actual power, the proportion occupied by antenna 1 should be as small as possible, and that the highest reception accuracy is desired, it can be said that among the three types of conductive plates shown in Figure 4 (first conductive plate 10a, second conductive plate 10b), it is preferable to set the size to (W1,L1)=(30mm,60mm).

[0033] Figures 2, 3, and 4 show performance comparisons when the position of the conductive member 10c is changed, and when the sizes of the first conductive plate 10a and the second conductive plate 10b are changed. From here, using Figures 5 and 6, we will examine the antenna performance when the sizes of the first conductive plate 10a and the second conductive plate 10b are different from those in Figures 2 and 3, and when the position of the conductive member 10c is changed. Specifically, we will explain the antenna performance when the connection position of the conductive member 10c is changed, using an antenna with the same shape as in Figure 1, where W1=15mm, L1=40mm, and H1=10mm. In other words, the antennas shown in Figures 5 and 6 have smaller areas of the first conductive plate 10a and the second conductive plate 10b than the antennas shown in Figures 2 and 3. Furthermore, the performance will be shown for the following arrangements of the conductive member 10c, where d is the distance from the center positions of the first conductive plate 10a and the second conductive plate 10b, and the direction approaching the feeder 11 is considered positive, with d=-20, d=-13.3333, d=-6.6667, d=0, d=6.6667, and d=13.3333.

[0034] Figure 5 is a graph showing the change in radiation efficiency according to the communication frequency for an antenna of a different size than the antenna shown in Figure 1. As shown in Figure 5, in the 920 megahertz band, the radiation efficiency is highest when d = -20, and it can be seen that it decreases as the position of the conductive member 10c approaches the feeder 11. More specifically, the radiation efficiency when d = -20 is 0.82041534, when d = -13.3333 is 0.78161097, when d = -6.6667 is 0.71846705, when d = 0 is 0.6318809, when d = 6.6667 is 0.52839634, and when d = 13.3333 is 0.43914519. These values ​​also show that when d=-20, i.e., when the conductive member 10c is placed on the opposite side of the feeder 11, the radiation efficiency is the highest among the simulated arrangements. On the other hand, when L1=40mm and W1=15mm, it is understood that the radiation efficiency is inferior to when L1=60mm and W1=30mm, but even with L1=40mm and W1=15mm, it is understood that the radiation efficiency is sufficient for wireless power transmission.

[0035] Figure 6 is a graph showing the changes in S-parameters for antenna 1 with L1=40mm and W1=15mm, according to the communication frequency. As shown in Figure 7, there is almost no difference in S-parameters in the 920 megahertz band, and it can be understood that there is no variation due to the placement of the conductive member 10c. More specifically, the S-parameter when d=-20 is -0.023152867, when d=-13.3333 is -0.025011792, when d=-6.6667 is -0.025784824, when d=0 is -0.020420918, when d=6.6667 is -0.020870058, and when d=13.3333 is -0.021026152. From these values, it can be seen that there is no difference.

[0036] The S-parameters shown in the graph in Figure 6 represent the reflection loss against 50Ω. Generally, a lower S-parameter value in decibels for the frequency band used indicates lower reflectivity, which is considered preferable. From the graph in Figure 6, it can be seen that, regardless of the position of the conductive member 10c, the antenna in this case is not very favorable in terms of reflection loss against 50Ω in the 920 megahertz band.

[0037] Figure 7 is a graph showing the changes in each S-parameter of an antenna with the dimensions W1=15mm and L1=40mm as shown in Figure 1, with respect to the communication frequency, assuming a distance of 1m from the power source. Figure 8 is a graph showing the changes in each S-parameter in the vertical direction as a result of the same antenna with respect to the communication frequency, assuming a distance of 1m from the power source.

[0038] In Figure 7, the values ​​for (S11, S12, S21, S22) in the 920 MHz band were (-46.70311, -21.271524, -21.164399, and -42.548009), respectively. Also, in Figure 8, the values ​​for (S11, S12, S21, S22) in the 920 MHz band were (-67.655771, -58.391212, -64.442047, and -87.938023), respectively. In either case, under matched conditions, antenna 1 showed a large negative decibel value for its S-parameter (S11) in the 920 MHz band, and S21 (transmission characteristics) was improved, indicating that it could feed power without problems at a distance of 1 m.

[0039] Figure 9 is a graph showing the radiation efficiency of antenna 1 for each communication frequency when W1 = 20 mm, L1 = 50 mm, and H1 = 10 mm. Furthermore, the performance will be shown for the following positions of the conductive member 10c, where d is the distance from the longitudinal center of the first conductive plate 10a and the second conductive plate 10b, and the direction approaching the feeder 11 is considered positive, with d = -25, d = -19.4444, d = -13.8889, d = -8.3333, d = -2.7778, d = 2.7778, d = 8.3333, d = 13.8889, and d = 19.4444.

[0040] As shown in Figure 9, even when W1 = 20 mm and L1 = 50 mm, the highest radiation efficiency in the 920 megahertz band is achieved when d = -25, that is, when the conductive member 10c is located at the end opposite in the longitudinal direction to the ends of the first conductive plate 10a and the second conductive plate 10b where the feeder 11 is provided. Basically, it can be understood that the closer the conductive member 10c is to the feeder 11, the lower the radiation efficiency becomes. More specifically, the radiation efficiency when d = -25 is 0.88334688, when d = -19.4444 is 0.87004885, when d = -13.8889 is 0.84695073, when d = -8.3333 is 0.81796392, and when d = -2.7778... The combined radiation efficiency is 0.78302769, the radiation efficiency when d=2.7778 is 0.74525835, the radiation efficiency when d=8.3333 is 0.7139987, the radiation efficiency when d=13.8889 is 0.70413104, and the radiation efficiency when d=19.4444 is 0.71853238. In other words, even when W1=20mm and L1=50mm, it can be seen that the radiation efficiency of the antenna 1 improves as the position of the conductive member 10c is moved further away from the feeder 11. Furthermore, even when W1=20mm and L1=50mm, regardless of where the conductive member 10c is placed, it shows a radiation efficiency of 0.7 or higher in the 920 megahertz band, so it can be said that it exhibits sufficient performance in wireless power transmission.

[0041] As can be seen from Figures 2 to 9, and as shown in Figure 10, the antenna with W1=30mm and L1=60mm has a higher radiation efficiency than the antenna with W1=20mm and L1=50mm, and the antenna with W1=15mm and L1=40mm. On the other hand, as the antenna area is increased, the radiation efficiency of the antenna tends to plateau around W1=15mm and L1=40mm, and it can be said that there is not much difference in performance between them. In fact, even with W1=15mm and L1=40mm, it performs sufficiently well as a receiving antenna in wireless power transmission. On the other hand, if the target on which the antenna is mounted is assumed to be a relatively small IoT device, then a smaller antenna size is desirable for IoT devices, so it is preferable to reduce the size of antenna 1 to 15×40mm. However, regardless of the size, antenna 1 according to the present invention can be said to perform at a certain level or higher as a receiving antenna in wireless power transmission.

[0042] Figure 11 shows an example of an antenna configuration different from that shown in Figure 1. Antenna 1A shown in Figure 11 shows an example in which the conductive member 10c in antenna 1 is configured as a single conductive plate. That is, antenna 1A shows an example in which the first conductive plate 10a and the second conductive plate 10b are connected at one end by a feeder 11 and at the other end by a conductive plate 10c, which is a conductive plate. The first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c may each be formed from individual plates and configured to be electrically connected to each other, or a single conductive plate may be bent to form the conductive plates 10a to 10c.

[0043] The upper part of Figure 12 is a graph showing the change in radiation efficiency according to the communication frequency when the antenna height is changed. The lower part of Figure 12 is a graph showing the change in radiation efficiency according to the communication frequency when the antenna width is changed. The upper part of Figure 12 shows the change in radiation efficiency of antenna 1A when the length and width of the first conductive plate 10a and the second conductive plate 10b are fixed (for example, L2 = 60 mm, W2 = 30 mm) and H2 is varied. As shown in the upper part of Figure 12, it can be seen that the radiation efficiency of antenna 1A increases as the height H2 increases. However, as shown in the upper part of Figure 12, it can be seen that the radiation efficiency levels off when the height H2 exceeds about 5 mm, and a significant improvement in radiation efficiency cannot be expected around 10 mm. Considering that antenna 1A will be mounted in small devices, it is desirable for its size to be as small as possible. Therefore, considering both size and radiation efficiency, it can be said that a height H2 of about 5 to 10 mm is appropriate. The same can be said for the height H1 of antenna 1 in Figure 1.

[0044] The lower part of Figure 12 shows the change in radiation efficiency of antenna 1A when the length and height of the first conductive plate 10a and the second conductive plate 10b are fixed (for example, L2 = 60 mm, H2 = 8 mm) and W2 is varied. As shown in the lower part of Figure 12, it can be seen that the radiation efficiency of antenna 1A increases as the width W2 increases. However, similar to the height, it can be seen from the lower part of Figure 12 that the rate of improvement in radiation efficiency decreases beyond a certain length. Specifically, the radiation efficiency levels off when the length of the width W2 exceeds about 10 mm. Therefore, considering both size and radiation efficiency, it can be said that the width W2 should be around 10 to 30 mm, but this may be limited by the size of the device on which antenna 1A is to be mounted.

[0045] Figure 13 shows the antenna pattern (directivity) when the antenna height is changed. In this embodiment, the center of antenna 1 is set as the origin, the plane parallel to the first conductive plate 10a and the second conductive plate 10b and passing through the origin is set as the XY plane, the short direction of antenna 1 (direction W1 in Figure 1) is set as the X axis, the long direction of antenna 1 (direction L1 in Figure 1) is set as the Y axis, the axis perpendicular to these X and Y axes is set as the Z axis, the angle of the Z axis with respect to the XY plane is set as Theta(θ), and the azimuth angle around the Z axis is set as Phi(Φ), and the antenna pattern shown is the antenna pattern as viewed from the direction indicated by the angle between Theta and Phi.

[0046] The antenna pattern shown in Figure 13 represents the antenna pattern centered on antenna 1 when antenna 1A is viewed from the front (a front view with feeder 11 to the right, conductive member 10c to the left, first conductive plate 10a at the top, and second conductive plate 10b at the bottom). In other words, it is the antenna pattern when Theta = 90° and Phi = 0°, and represents the antenna pattern in the YZ plane. Since antenna 1A is used as a receiving antenna in wireless power transfer, and because it is not possible to predict where devices such as sensors on which antenna 1A is mounted will be placed, it is desirable that the directivity of antenna 1A be as uniform as possible. Figure 13 shows the antenna patterns (directivity) when the areas of the first conductive plate 10a and the second conductive plate 10b of antenna 1A are fixed, and the height H1 is set to 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm.

[0047] As shown in Figure 13, when the height H2 is 2 mm, there are significant indentations in the antenna pattern at 0 and 180 degrees. As the height H2 increases, these indentations decrease, and when H2 = 10 mm, the indentations are small and the antenna pattern becomes closer to a circle (closer to omnidirectional). Therefore, it can be understood that among these heights, H2 = 10 mm is preferable for a receiving antenna. It is not the case that the higher H2, the better, and it also depends on the load capacity of the device on which antenna 1A is mounted. Furthermore, it is preferable to set H2 to a height that does not distort the antenna pattern when it is increased.

[0048] From the details shown in Figures 2 to 13 above, in the antenna 1 shown in Figure 1, where the long, plate-shaped first conductive plate 10a and second conductive plate 10b are facing each other and connected at one end by a feeder 11, and further connected by a conductive member 10c, it is preferable that the distance between the first conductive plate 10a and the second conductive plate 10b, i.e., the height of the antenna 1, be about 10 mm, and it is preferable that the conductive member 10c be connected to the first conductive plate 10a and the second conductive plate 10b at a position as far away from the feeder 11 as possible, i.e., at the other end opposite to the end where the feeder 11 is located. Furthermore, regarding the size of the first conductive plate 10a and the second conductive plate 10b, it is preferable that they be in the range centered around 15 mm × 40 mm among the various sizes mentioned above, but regardless of the size of the antenna, as long as the antenna length is close to 1 / 4λ of 920 megahertz in the shape shown in Figures 1 and 11, it will function as a sufficiently power-receiving antenna.

[0049] Figures 14(a) to 14(f) show various variations of the antenna according to the present invention and illustrate various antenna configurations. In Figures 14(a) to 14(f), although not indicated by reference numerals, the following explanation will proceed under the assumption that, as shown in Figure 11, the base consists of a first conductive plate 10a, a second conductive plate 10b, and a conductive plate 10c arranged in a U-shape, with the ends of the first conductive plate 10a and the conductive plate 10c connected by a feeder 11.

[0050] Antenna 1a shown in Figure 14(a) is identical to antenna 1A shown in Figure 11. Figure 14 is shown for comparison with other embodiments.

[0051] The antenna 1b shown in Figure 14(b) is a modified version of antenna 1a. The antenna 1b shown in Figure 14(b) has a shape in which a protrusion is provided in the center of the first conductive plate 10a of antenna 1a that protrudes toward the second conductive plate 10b, and a protrusion is provided in the center of the second conductive plate 10b that protrudes toward the first conductive plate 10a. That is, antenna 1b comprises a first conductive plate 10a, a second conductive plate 10b facing the first conductive plate 10a, a conductive plate 10c, and a feeder 11. The conductive plate 10c connects one end of the first conductive plate 10a to one end of the second conductive plate 10b that faces the one end of the first conductive plate 10a, and the feeder 11 connects the other end of the first conductive plate 10a to the other end of the second conductive plate 10b that faces the other end of the first conductive plate 10a.

[0052] The antenna 1c shown in Figure 14(c) is another modification of antenna 1a. As shown in Figure 14(c), it has the shape of antenna 1a with the outer edges of the conductive plates 10a to 10c remaining. In other words, antenna 1c has a configuration in which the conductive plates 10a to 10c are formed from a single conductive plate, and the conductive plate, with a predetermined distance inward from the end of each side, is bent to the state shown in Figure 14(c) and the ends are connected by feeders 11. The device comprises a U-shaped first conductive plate 10a, a U-shaped second conductive plate 10b facing the first conductive plate 10a, a frame-shaped conductive plate 10c, and a feeder 11. The conductive plate 10c connects one end of the first conductive plate 10a to one end of the second conductive plate 10b facing the first conductive plate 10a, and the feeder 11 connects the other end of the first conductive plate 10a to the other end of the second conductive plate 10b facing the other end of the first conductive plate 10a.

[0053] The antenna 1d shown in Figure 14(d) is an antenna in which the inside of the conductive plate 10c is cut out to form a frame shape in antenna 1a. That is, antenna 1d comprises a first conductive plate 10a, a second conductive plate 10b facing the first conductive plate 10a, a frame-shaped conductive plate 10c, and a feeder 11. The conductive plate 10c connects one end of the first conductive plate 10a to one end of the second conductive plate 10b facing the one end of the first conductive plate 10a, and the feeder 11 connects the other end of the first conductive plate 10a to the other end of the second conductive plate 10b facing the other end of the first conductive plate 10a.

[0054] The antenna 1e shown in Figure 14(e) has a configuration in which slots are provided in the first conductive plate 10a and the second conductive plate 10b in addition to the antenna 1d. That is, the antenna 1e consists of a first conductive plate 10a with a slot extending in the longitudinal direction and a second conductive plate 10b with a slot extending in the longitudinal direction, which face each other and are connected at one end by a feeder 11 and at the other end by a plate-shaped conductive member 10c.

[0055] The antenna 1f shown in Figure 14(f) has a configuration that, in addition to the antenna 1e, has protrusions 10d extending toward the second conductive plate 10b from both ends in the W2 direction near the longitudinal center of the first conductive plate 10a. That is, the antenna 1f consists of a second conductive plate 10b with a slot extending in the longitudinal direction and a first conductive plate 10a with a slot extending in the longitudinal direction and a protrusion 10d extending vertically at the end in the width direction near the longitudinal center, which face each other, connected at one end by a feeder 11 and connected at the other end by a plate-shaped conductive member 10c.

[0056] Figure 15 shows the antenna 1f shown in Figure 14(f) and a partially enlarged view thereof. As shown in the partially enlarged view of Figure 15, the projection 10d, which is at the end of the first conductive plate 10a in the width (W) direction and protrudes from near the center in the length (L) direction, extends from the first conductive plate 10a toward the second conductive plate 10b, but does not connect to the second conductive plate 10b. That is, a predetermined gap is provided between the second conductive plate 10b and the projection 10d. The performance of the antenna 1f also varies depending on the length of this gap. This point will be explained later using Figure 19.

[0057] Below, we will examine the desirable shape for antenna 1 by comparing the performance of each antenna shown in Figure 14.

[0058] Figure 16 is a graph showing the changes in radiation efficiency for each antenna shown in Figure 14 according to the communication frequency. As shown in Figure 16, in the 920 MHz band, antenna 1f, antenna 1a, antenna 1d, antenna 1b, antenna 1e, and antenna 1c show the highest radiation efficiency in that order. More specifically, simulations revealed that the radiation efficiency of antenna 1f in the 920 MHz band is 0.99010068, antenna 1a is 0.93002356, antenna 1d is 0.90709889, antenna 1b is 0.90532426, antenna 1e is 0.90475959, and antenna 1c is 0.79928906. From this, it follows that the antenna most suitable for the 920 megahertz band, in terms of radiation efficiency, is the 1f antenna shape. However, regardless of the shape, since they all have a radiation efficiency of 0.7 or higher, they can be said to meet the requirements for a receiving antenna.

[0059] Figure 17 shows the antenna patterns (directivity) of each antenna shown in Figure 14. The antenna patterns on the right side of Figure 17 show the antenna patterns measured for each antenna shown in Figure 14, viewed from the top surface (the side of the first conductive plate 10a), with the feeder 11 positioned at the top. In other words, it shows the antenna patterns on the XY plane when θ = 90°. Simulations have shown that the antenna patterns viewed from the top surface are nearly perfect circles for all of the antennas shown in Figure 14. Therefore, it can be said that there is no significant difference between the antennas in terms of the antenna patterns viewed from the top surface.

[0060] On the other hand, the antenna patterns on the left side of Figure 17 show the antenna patterns of each antenna shown in Figure 14 when viewed from the conductive member 10c side. That is, it shows the antenna patterns on the XZ plane when Φ = 90°. In the antenna patterns shown in Figure 17, each antenna pattern is elliptical, with the major axis radius in the 90-degree direction and the minor axis radii in the 0-degree and 180-degree directions. The minor axis radius of the antenna pattern of antenna 1f is the longest, and the antenna pattern drawn by antenna 1f is the closest to a circle. As shown in the figure, the minor axis radii of the antenna patterns become shorter in the order of antenna 1f, antenna 1e, antenna 1c, antenna 1a, and antenna 1b. The antennas shown in Figure 14 are intended to be used as receiving antennas in wireless power transfer, as described above, and one example is their intended use in small sensors as IoT devices. In this case, since the location where the IoT device will be installed is unknown, it is preferable that the antenna pattern be such that it can receive and power from radio waves from any direction. Therefore, among the antennas shown from antenna 1a to antenna 1f, antenna 1f is the most preferable in terms of antenna pattern.

[0061] Based on Figures 16 and 17, it can be inferred that among the antenna group shown in Figure 14, antenna 1f is the most suitable as a receiving antenna for wireless power transmission. The reason why antenna 1f showed high suitability will be explained using Figure 18.

[0062] Figure 18 shows that the antenna shown in Figure 14(f) functions as a composite antenna. From Figures 16 and 17, it can be seen that antenna 1f is efficient as a receiving antenna, and this is because it is presumed that antenna 1f functions as a composite antenna as shown in Figure 18.

[0063] As shown in Figure 18, it is estimated that antenna 1f functions as two loop antennas, two slot antennas, and three dipole antennas. That is, antenna 1f can be considered as a composite antenna having parts that function as six types of antennas: a loop antenna 18g consisting of the perimeter of the frame of the conductive member 10c, a loop antenna 18f formed by the first conductive plate 10a - conductive member 10c - second conductive plate 10b - end of the feeder 11, a slot antenna 18d formed by a slot provided in the first conductive plate 10a, a slot antenna 18e formed by a slot provided in the second conductive plate 10b, dipole antennas 18a and 18c consisting of the feeder 11 - to the center of the first conductive plate 10a - protrusion 10d, and a dipole antenna 18b consisting of the first conductive plate 10a - feeder 11. As a result, it exhibits excellent antenna performance.

[0064] Figure 19 is a graph showing the radiation efficiency of the antenna according to the communication frequency when the gap between the antenna protrusion 10d and the second conductive plate 10b shown in Figure 14(f) is changed. In the graph shown in Figure 19, the horizontal axis is frequency and the vertical axis is the decibel value, with lower decibel values ​​indicating lower efficiency.

[0065] Figure 19 shows the radiation efficiency when the distance (gap) between the protrusion 10d and the second conductive plate 10b is changed within the range of 0 to 2.48 mm. As shown in Figure 19, the radiation efficiency differs between cases with no gap (0 mm) and other cases, and it can be seen that the radiation efficiency is significantly lower in the gapless configuration compared to the configuration with a gap. More specifically, for gaps other than 0 mm, the radiation efficiency was around 90%. From this, it can be concluded that in antenna 1f, it is better to provide a gap between the protrusion from the first conductive plate 10a and the second conductive plate 10b.

[0066] Figure 20 shows the antenna pattern (directivity) of the antenna when the gap between the antenna protrusion shown in Figure 14(f) and the second conductive plate is changed. Figure 20 shows examples of antenna patterns when the gap is 0.02 mm, 0.13 mm, 0.2 mm, and 0.6 mm. The left side of Figure 20 shows the antenna pattern when antenna 1f is viewed from the top side and the long direction of antenna 1f is the left-right direction in the drawing, while the right side of Figure 20 shows the antenna pattern when antenna 1f is viewed from the end, i.e., from the feeder 11. Specifically, the left side of Figure 20 shows the antenna pattern on the YZ plane when Φ = 0°. The right side of Figure 20 shows the antenna pattern on the XZ plane when Φ = 90°.

[0067] As shown in Figure 20, simulations revealed that a gap of 0.13 mm formed the closest to a circle, followed by smaller gaps of 0.02 mm, 0.6 mm, and 0.2 mm, resulting in an antenna pattern closer to an ellipse. As mentioned above, the antenna according to this embodiment is used as a receiving antenna in wireless power transfer, and since its installation location is unknown during the manufacturing stage, it is desirable to form an omnidirectional antenna pattern that covers as wide an area as possible.

[0068] Therefore, as shown in Figure 20, (i) the antenna pattern is closest to a perfect circle, (ii) even when the gap is narrowed, the radiation efficiency does not deteriorate significantly compared to the case where the gap with the best radiation efficiency was 2.48 mm, and (iii) the antenna pattern when the gap with the best radiation efficiency was 0.6 mm is significantly inferior to the antenna patterns when the gap is narrower, such as 0.13 mm and 0.02 mm (the antenna pattern is elliptical). Thus, from Figures 19 and 20, it can be said that in the case of antenna 1f, it is better to provide a gap between the protrusion and the second conductive plate 10b, and the distance of this gap should be as short as possible so that the antenna pattern formed by antenna 1f is close to omnidirectional.

[0069] Figure 21 shows an example of an antenna configuration when it is made spherical. More specifically, the antenna shown in Figure 21 is an example of an antenna 1f shown in Figure 14(f) being made curved (spherical in the illustration). As shown in Figure 21, the antenna 1g consists of a first conductive plate 10a with a slot and a second conductive plate 10b with a slot, with one end connected by a frame-shaped conductive member 10c with a cutout inside, and the other end connected by a feeder 11. The first conductive plate 10a, the second conductive plate 10b, and the conductive member 10c are all curved spherically as shown in the illustration. In addition, a plate-shaped projection is provided that protrudes from the middle of the first conductive plate 10a toward the second conductive plate 10b, and as shown in the illustration, this projection does not come into contact with the second conductive plate 10b.

[0070] Figure 22 is a graph showing the radiation efficiency of the antenna shown in Figure 21 according to the communication frequency.

[0071] As shown in Figure 22, antenna 1g, with the shape shown in Figure 21, exhibits a high radiation efficiency of 0.95751033 in the 920 megahertz band, demonstrating sufficient performance as a receiving antenna.

[0072] Figure 23 shows the antenna pattern (directivity) of the antenna shown in Figure 21. The left side of Figure 23 shows the antenna pattern when antenna 1g is viewed from the top, i.e., from arrow 21A in Figure 21. The center side of Figure 23 shows the antenna pattern when antenna 1g is viewed from the side, i.e., from arrow 21B in Figure 21. The right side of Figure 23 shows the antenna pattern when antenna 1g is viewed from the front, i.e., from arrow 21C in Figure 21. In other words, the left side of Figure 23 shows the antenna pattern on the XY plane when Φ=0°, the center of Figure 23 shows the antenna pattern on the XZ plane when θ=90°, and the right side of Figure 23 shows the antenna pattern on the YZ plane when Φ=90°.

[0073] As shown in Figure 23, the antenna pattern of antenna 1g is nearly circular in shape, although it is slightly elliptical in the left and right diagrams of Figure 23, and nearly circular in shape in the center diagram. This indicates that it has an antenna pattern that is nearly ideal for an omnidirectional antenna.

[0074] Therefore, it was found that antenna 1g, which is constructed by curving antenna 1f as shown in Figure 21, can also be used as a receiving antenna.

[0075] Figure 24 shows an example of an antenna configuration when it is configured in a columnar (ring-shaped) form. More specifically, the antenna shown in Figure 21 is an example of the antenna 1f shown in Figure 14(f) being configured in a columnar form. As shown in Figure 24, antenna 1h shows an example of antenna 1f being curved in the longitudinal direction to form a columnar form. It consists of a first conductive plate 10a, which is a long plate-shaped structure with a slot and is curved in the longitudinal direction, and a second conductive plate 10b, which is a long plate-shaped structure with a slot and is curved in the longitudinal direction. These are connected at one end by a curved, frame-shaped conductive member 10c with a cutout inside, and at the other end by a feeder 11.

[0076] Figure 25 is a graph showing the radiation efficiency of antenna 1h shown in Figure 24 according to the communication frequency. As shown in Figure 25, antenna 1h, with the shape shown in Figure 24, shows a high radiation efficiency of 0.95761551 in the 920 megahertz band, demonstrating that it exhibits sufficiently high performance as a receiving antenna.

[0077] Figure 26 shows the antenna pattern (directivity) of antenna 1h shown in Figure 24. The left side of Figure 26 shows the antenna pattern when antenna 1h is viewed from the direction of arrow 24A, the center side of Figure 26 shows the antenna pattern when antenna 1h is viewed from the direction of arrow 24B, and the right side of Figure 26 shows the antenna pattern when antenna 1h is viewed from the direction of arrow 24C. In other words, the left side of Figure 26 shows the antenna pattern on the YZ plane when Φ = 90°, the center of Figure 26 shows the antenna pattern on the XY plane when Φ = 0°, and the right side of Figure 26 shows the antenna pattern on the XZ plane when θ = 0°. As shown in Figure 26, although the antenna pattern viewed from the direction of arrows 24A and 24B is elliptical, the distortion is not significant, and the antenna pattern viewed from the direction of arrow 24C is almost circular. Therefore, antenna 1h can be said to be a receiving antenna that is sufficiently suitable for use as an omnidirectional receiving antenna.

[0078] As shown in Figures 21 to 26, when the antenna 1f is configured in a spherical or columnar shape, it can be seen that it has a certain suitability as a receiving antenna for wireless power transfer, compared to when the antenna 1f is configured in a box shape as shown in Figure 14(f). As an example of such a shaped antenna 1f, it can be connected to a motion sensor and, for example, attached to a columnar pen holder, allowing an IoT device equipped with the antenna 1f to be installed in a natural manner without attracting the attention of people. This IoT device may operate using the power received by the antenna 1f to perform sensing and transmit the data obtained from the sensing.

[0079] Figure 27 shows an example of an antenna configuration when a power receiving circuit is provided on one of the conductive plates. In the example shown in Figure 27, a power receiving circuit is provided on the first conductive plate 10a, and the power receiving circuit and the second conductive plate 10b are connected via a feeder 11. Although Figure 27 shows an example where the second conductive plate 10b is narrowed and extended in the direction of the first conductive plate 10a, the conductive member connected to the second conductive plate 10b may also be connected to the power receiving circuit via the feeder 11.

[0080] By configuring it as shown in Figure 27, the antenna 1 can be easily constructed, and its rigidity can be improved compared to the cases shown in Figures 1 and 11. The performance of the antenna shown in Figure 27 will be explained using Figures 28 and 29.

[0081] Figure 28 is a graph showing the radiation efficiency of the antenna shown in Figure 27 according to the communication frequency. As shown in Figure 28, the radiation efficiency of the antenna shown in Figure 28 represents the radiation efficiency of the antenna according to the combined thickness of the first conductive plate 10a and the PCB (Printed Circuit Board) which includes the power receiving and storage circuits, sensors, energy storage device, and microcontroller. Specifically, simulations were performed in three cases: when the combined thickness of the first conductive plate 10a and the PCB was 0.3 mm, when the combined thickness of the first conductive plate 10a and the PCB was 1 mm, and when the first conductive plate 10a and the PCB were bonded together to a thickness of 0.3 mm. The graph showing the radiation efficiency shown in Figure 28 was obtained. According to this graph, the radiation efficiency of each antenna in the 920 megahertz band was 0.79228273 for the antenna with the first conductive plate 10a and PCB bonded together to a thickness of 0.3 mm, 0.62782387 for the antenna with the first conductive plate 10a and PCB bonded together to a thickness of 1 mm, and 0.59796367 for the antenna with the first conductive plate 10a and PCB not bonded together to a thickness of 0.3 mm. It can be seen that the efficiency was highest in this order.

[0082] Based on the radiation efficiency shown in Figure 28, it can be inferred that the first conductive plate 10a of the antenna and the PCB should be bonded together, and that a thinner thickness is preferable. Figure 29 shows the antenna pattern (directivity) of the antenna shown in Figure 27. The antenna pattern shown in Figure 29 is the antenna pattern of the antenna shown in Figure 27 when viewed from above. As shown in the figure, it is elliptical in both cases, and there can be said to be no significant difference. Therefore, considering Figures 28 and 29 together, it can be inferred that the first conductive plate 10a of the antenna and the PCB should be bonded together, and that the thickness should be thin.

[0083] Although not shown in the diagram, as mentioned above, the antenna 1 (1A, 1a~1h) in this embodiment may be configured as a receiving antenna in wireless power transfer, and may be configured as an IoT device that receives and stores power transmitted from a transmitter by a capacitor or the like, and supplies it as power to operate sensors, etc. The power received by antenna 1 may be supplied directly to sensors, etc., and the sensing data obtained by sensing may be transmitted to an external server device, etc., from a separate communication circuit using the power received by antenna 1. In this case, antenna 1 may also be used as a communication antenna for sending and receiving data if communication is possible as needed.

[0084] Figure 30 is a schematic diagram showing an example of an IoT device formed by casing the antenna 1 according to this embodiment. Figure 30(a) is an external view of the IoT device, and Figure 30(b) is an internal perspective view of the IoT device. Figure 31 is an exploded perspective view of the IoT device shown in Figure 30(a).

[0085] As shown in Figure 30(a), the IoT device may be provided as a box-shaped enclosure 3000 as an example. As shown in Figure 30(b), the enclosure 3000 contains an example of an antenna according to this embodiment, which includes an antenna 1f and a PCB 3001 that is mounted on and connected to the antenna 1f. Note that the enclosure 3000 is not limited to a box shape as long as it contains the antenna 1 and the PCB 3001 inside, it may be, for example, columnar, conical, or spherical.

[0086] Figure 31 is an exploded perspective view of the disassembled housing 3000. As shown in Figure 31, a PCB 3001 is provided and connected to the antenna 1f. Although not shown, the PCB 3001 is equipped with various circuits that implement functions necessary for an IoT device, such as sensors corresponding to sensing performed as an IoT device, a power receiving circuit, a power storage circuit, a power storage device, and a microcontroller. The antenna 1f with the PCB 3001 is then sandwiched and housed between the upper housing 3100 and the lower housing 3101 to form an IoT device. Thus, the antenna 1 according to this embodiment may be provided as part of an IoT device.

[0087] When provided as an IoT device, by selecting and installing the most appropriate size and highest power receiving performance antenna 1 according to the size of the IoT device, it is possible to provide an IoT device that can continue to operate as long as it can receive power from the power transmitter while achieving the desired functions. In the case of this IoT device, there is no need to install a large battery that is necessary to operate the IoT device, so the size can be made relatively small and the cost increase that would be associated with installing a large battery can be suppressed. Note that in Figure 31, a slot is shown in the PCB to match the antenna 1f, but a slot is not required in the PCB.

[0088] Furthermore, the antenna 1 may have a variable structure. For example, the antenna length may be changed by using a structure in which the conductive member 10c and the feeder 11 are retractable members (for example, members that can be extended or retracted by a sliding mechanism, etc.) to change their lengths.

[0089] The receiving antenna according to the present invention can efficiently receive power transmitted from a transmitter located at a certain distance or greater (for example, 1 m, but not limited to 1 m, and may be greater than 1 m). Furthermore, the receiving antenna according to the present invention can have a smaller planar area than the planar loop antenna commonly used in general wireless power transfer, and can be provided as a receiving antenna that is easy to use in IoT devices equipped with sensor devices. In addition, the antenna according to this embodiment can obtain a certain level of radiation efficiency even when changed to various sizes, so when used built into devices of various sizes, it can be provided as an antenna that has a certain level of power receiving performance while being sized according to the device. Moreover, the antenna according to this embodiment is an antenna that has a radiation pattern in which the directivity is almost 0 dBi in all directions, and a device equipped with this antenna can receive power and operate regardless of where it is placed within a predetermined distance from the power transmitter that transmits power, as long as there are no objects that interfere with wireless power transmission in between.

[0090] The antenna 1A shown in Figure 11 may be treated as, for example, an inverted F antenna. When antenna 1A is treated as an inverted F antenna, for example, the first conductive plate 10a becomes the antenna element, the second conductive plate 10b becomes the ground for the first conductive plate 10a, and the conductive plate 10c becomes the short circuit. The first conductive plate 10a is short-circuited to the second conductive plate 10b by the conductive plate 10c. In Figure 11, the width of the first conductive plate 10a and the width of the second conductive plate 10b, which acts as the ground, are approximately the same. Also in Figure 11, the widths of the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c are approximately the same.

[0091] In Figure 11, the ends of the first conductive plate 10a and the second conductive plate 10b opposite to the ends connected by conductive plate 10c are connected via feeder 11. In a typical inverted F antenna, the short-circuit section and the feed section are located at a predetermined distance from each other. In antenna 1A, by connecting the ends of the first conductive plate 10a and the second conductive plate 10b opposite to the ends connected by conductive plate 10c via feeder 11, good simulation results were obtained for radiation efficiency, reflectivity, and directivity.

[0092] The length L2 of antenna 1A is, for example, 40mm to 60mm, as shown in Figure 10. This length is approximately one-quarter the wavelength λ of the 920 megahertz band radio waves that antenna 1A is expected to receive. In this explanation, "approximately the same length" means, for example, that the number of digits of the numerical value is the same, that is, the difference is less than 10 times. By having a length L2 of 40mm to 60mm, antenna 1A can efficiently receive radio waves in the 920 megahertz band.

[0093] The characteristic impedances of the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c are designed to match the characteristic impedance of the feeder 11. Specifically, for example, the characteristic impedances of the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c are matched using complex conjugate. For example, the characteristic impedances of the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c are designed to be R + jX. The characteristic impedance of the feeder 11 is designed to be R - jX.

[0094] In a typical inverted-F antenna, when a coaxial cable with a predetermined characteristic impedance is attached to the feed point, it is necessary to match the characteristic impedance of the antenna to the characteristic impedance of the coaxial cable. In this embodiment, only the real part of the characteristic impedance is matched, and the imaginary part is canceled out by the complex conjugate, making it possible to perform impedance matching efficiently. Generally, insertion loss increases as the values ​​of inductance and capacitance increase, so by reducing the number of components and their values, it is possible to perform matching with reduced loss. In particular, it is ideal that the value of R in the characteristic impedance R+jX of the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c is equal to the value of R in the characteristic impedance R-jX (complex conjugate) of the feeder 11 (rectifier circuit, etc.). Therefore, in order to achieve this, it is necessary to avoid the vicinity of the antenna resonance (λ / 4) and determine the length of the substrate where the R value is common at a low or high frequency.

[0095] Antenna 1A has a second conductive plate 10b as a ground, which prevents the antenna characteristics from being affected by the surface material of the component to which it is attached. This allows antenna 1A to be mounted on metal surfaces, conductive equipment, or sensors, significantly improving usability.

[0096] Next, we will explain the Z-parameter, or impedance, of antenna 1 shown in Figure 1. Figure 42 shows the change in Z parameters, i.e., impedance, of antenna 1 shown in Figure 1 at various frequencies. Figure 42 shows the simulation results for each frequency of both the real and imaginary parts. In Figure 42, the upper graph shows the Z parameters corresponding to the real communication frequency, and the lower graph shows the Z parameters corresponding to the imaginary communication frequency. The imaginary component is also called reactance.

[0097] According to Figure 42, the impedance and reactance values ​​in the 920 megahertz band when the position of the conductive member 10c is changed are as follows: when d=-30, (real part, imaginary part) = (6513.8669Ω, -2519.7886Ω), when d=-23.3333, (real part, imaginary part) = (6096.2638Ω, -2551.2409Ω), when d=-16.6667, (real part, imaginary part) = (5876.8777Ω, -2089.0102Ω), when d=-10, (real part, imaginary part) = (5154.6372Ω, -1921.7748Ω), when d=-3.3333 When d=3.3333, the (real part, imaginary part) = (4282.2143Ω, -1713.465Ω), (real part, imaginary part) = (3278.0904Ω, -1488.178Ω) when d=10, (real part, imaginary part) = (2220.3885Ω, -1198.5983Ω) when d=16.6667, (real part, imaginary part) = (1301.1842Ω, -730.6931Ω) when d=23.3333, (real part, imaginary part) = (268.3113Ω, -80.5999Ω) when d=30, (real part, imaginary part) = (555.1255Ω, -153.2234Ω).

[0098] According to the upper graph in Figure 42, the impedance increases sharply around the 920 megahertz band, regardless of the position of the conductive member 10c. From this, it can be understood that antenna 1 is an antenna that resonates in the 920 megahertz band. Furthermore, a higher dB value indicates a higher degree of resonance. According to Figure 42, the impedance is highest in the 920 megahertz band when d = -30. Therefore, the radiation efficiency is highest when the conductive member 10c is placed at the position where d = -30, that is, the position furthest from the feeder 11.

[0099] Assuming that R+jX is the antenna impedance, there are two points where the real part is R (Figure 44). As explained above, the ideal is when the antenna impedance is the complex conjugate of the rectifier circuit. Ideally, the antenna impedance is R+jX and the rectifier circuit impedance is R-jX, but achieving this matching in practice is difficult. Generally, the real part of the rectifier circuit is 50 ohms or less, often around several tens of ohms. Therefore, near the antenna resonance, the R value becomes very high, several thousand ohms, but it is good to match this to several tens of ohms.

[0100] As explained in Figure 44, matching the real impedance of the antenna with the real impedance of the rectifier is possible at low frequencies by reducing the R value by shortening the antenna length L by 10-30%, preferably by about 20%, thereby matching to the desired R value. At high frequencies, it is possible to reduce the R value by increasing the antenna length L by 10-30%, preferably by about 20%, thereby matching to the desired R value. By performing impedance matching at low frequencies, it becomes possible to shorten the antenna length L by about 10-30% from the initial state, making it possible to miniaturize the entire antenna. If the R value falls below the specified target value, meaning the R value is too low, and you want to increase it, you can adjust the R value by increasing the antenna length L in the lower frequency band and decreasing the antenna length L in the higher frequency band. The ideal antenna length is 1 / 4 wavelength, but by adjusting the antenna length by about ±20%, it is possible to approach the ideal match.

[0101] If the respective impedance R values ​​can be matched, only the jX value needs to be adjusted, so impedance matching can be achieved with just one component. As an example, at 920 megahertz, impedance matching between the antenna and rectifier is performed by inserting a 22nH inductor in series with an antenna (using Teflon® as the base material) that is 60mm long, 16mm wide, and 8mm high. When the initial state of the antenna is set to a length where the frequency band of the radio waves to be received is the resonant frequency, that is, for example, 1 / 4 the length of the receiving wavelength λ, it is possible to shorten the antenna length L by about 10-30%, preferably about 20%, from the initial state by performing impedance matching at a low frequency, thereby enabling miniaturization of the entire antenna.

[0102] Based on the above, it is preferable to arrange the conductive member 10c as far away from the feeder 11 as possible, and, if possible, to connect the first conductive plate 10a and the second conductive plate 10b to the ends opposite to the ends where the feeder 11 is provided.

[0103] (Example 2) In Example 1, various forms of receiving antennas 1, 1A, and 1a-1h were described with reference to Figures 1-31 and 42. Next, we will describe the antenna 20 according to Example 2. To avoid duplication of information, the following explanations will be omitted for parts that overlap with antennas 1, 1A, and 1a-1h related to Example 1.

[0104] The antenna 20 according to Example 2 can be used as a receiving device in wireless power transmission, similar to Example 1. In other words, the antenna 20 according to Embodiment 2 can be used as a power receiving device that receives energy wirelessly transmitted in three-dimensional space based on WPT (Wireless Power Transmission or Wireless Power Transfer). The antenna 20 according to Example 2 can transmit the received energy to any object such as a sensor, robot, equipment, or PC. The antenna 20 according to Example 2 can be implemented as an antenna or a rectenna. The antenna 20 according to Example 2 can be implemented as a module (antenna module, etc.) that integrates the antenna or rectenna with related electronic components. The antenna 20 according to Example 2 can be implemented as a module (sensor module, etc.) that integrates the antenna or rectenna, related electronic components, and a sensor or the like that is to be powered.

[0105] First, the basic configuration of the antenna 20 according to Example 2 will be explained with reference to Figures 32 to 37. Figure 32 is an example of a diagram showing the basic configuration of the antenna according to Example 2 and the core material that can be applied thereto. Referring to Figure 32(A), a perspective view of the antenna 20 according to Example 2 is shown, viewed from a similar direction to that of the antenna 1A, etc., according to Example 1, as illustrated in Figure 11. Referring to Figure 32(B), an example of a perspective view of the antenna 20 viewed from the opposite direction is shown. These figures allow the basic configuration of the antenna 20 according to Embodiment 2 to be understood from all sides. In the receiving antennas 1, 1A, and 1a-1h in Example 1, the plate thickness was omitted, and the structure was only schematically illustrated (see, for example, Figures 11 and 14(a)-(f)). Figures 32(A) and (B) illustrate the plate thickness of antenna 20 in more detail.

[0106] The antenna 20 illustrated in Figure 32(A) has a polyhedral shape. Preferably, the antenna 20 has a substantially rectangular parallelepiped shape. In particular, the antenna 20 illustrated in Figure 32(A) has a predetermined width dimension (X-axis direction) W3, a length dimension (Y-axis direction) L3, and a height dimension (Z-axis direction) H3. Depending on the embodiment, each dimension can be appropriately adjusted. For example, the height dimension H3 may be kept relatively small to achieve a low profile overall. Alternatively, the area calculated by the product of the width dimension W3 and the length dimension L3 may be kept small to minimize the overall installation area.

[0107] The antenna 20 illustrated in Figure 32(A) is similar to Embodiment 1 illustrated in Figure 11 in that the first conductive plate (conductive member) 21 and the second conductive plate (conductive member) 22 are arranged facing each other, and are connected to each other at one end via a feeder (rectifier) ​​25, and at the opposite end via a third conductive plate (conductive member) 23. The first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 are made of any material that conducts electric current well, such as copper or aluminum. Therefore, the first conductive plate 21, the third conductive plate 23, the second conductive plate 22, and the feeder 25 create a closed current path, and a loop antenna 50 is formed as illustrated by the arrows in Figures 32(A) and (B).

[0108] The loop antenna 50 described here is not strictly a typical "loop antenna," but since a loop is formed by the three conductive plates and the feeder 25, it is referred to as a "loop antenna" in this embodiment. This antenna functions, for example, as a power supply antenna. Similarly, the loop antenna 18f, illustrated in Figure 18 of Embodiment 1, which is formed by the first conductive plate 10a, conductive member 10c, second conductive plate 10b, and the end of the feeder 11, is also referred to as a "loop antenna" because, strictly speaking, its principle is slightly different from a typical loop antenna, but a loop is formed. Furthermore, the direction of the arrows on the loop antenna 50 illustrated in Figures 32(A) and (B) may be reversed.

[0109] Preferably, the first conductive plate 21 and the second conductive plate 22 are spaced apart from each other by a predetermined distance, and extend substantially parallel to each other in substantially the same direction. However, the first conductive plate 21 and the second conductive plate 22 are not limited to being parallel to each other. Preferably, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 are each formed in the shape of an elongated plate. The length and direction of the four sides of the elongated plate shape of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 can be modified in various ways. Furthermore, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 may be flat, curved, or a combination thereof, either entirely or partially. In the illustrated embodiment, the third conductive plate 23 is connected to the first conductive plate 21 and the second conductive plate 22 at approximately perpendicular angles. However, as will be detailed below, the connection angle of the third conductive plate 23 is not limited to 90 degrees, particularly from the viewpoint of the efficiency of the loop antenna 50.

[0110] Preferably, a single conductive plate is bent to form the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23. For example, a single copper plate is bent to form the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 such that they have a roughly U-shape (roughly U-shaped or roughly C-shaped) cross-section. In the bending process, for example, a mold may be used to plastically deform the copper plate or the like. However, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 may each be formed from individual conductive plates and connected to each other in a way that allows them to conduct electricity.

[0111] In Embodiment 2, a hollow space 24 of a predetermined size can be defined by punching out at least one of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23. For example, a roughly rectangular hollow space 24 may be defined at any location by press punching out the third conductive member 23. The size and shape of this hollow space can be determined so that an inverted F antenna 60 can be mounted therein.

[0112] In Example 1, the antenna 1d illustrated in Figures 14(d) and 18 is formed by cutting out the inside of the conductive plate 10c to create a loop antenna 18g around its frame. In Example 2, although the inside of the conductive plate 23 is similarly cut out, the main purpose of this cutout is not to form a loop antenna. Therefore, in Example 2, the size and thickness of the frame that defines the hollow space 24 (sometimes called a cutout or notch) may differ from that of Example 1.

[0113] Therefore, the antenna 20 illustrated in Figures 32(A) and (B) can be configured as a dual-band antenna having a loop antenna 50 consisting of a first conductive plate 21, a second conductive plate 22, a third conductive plate 23 and a feeder 25, and an inverted F-type antenna 60 arranged in the hollow space 24 of the third conductive plate 23.

[0114] The loop antenna 50 and the inverted F antenna 60 utilize two different frequency antenna patterns. Therefore, the loop antenna 50 and the inverted F antenna 60 can be used for different purposes. For example, the loop antenna 50 can be used as a power receiving antenna, while the inverted F antenna 60 can be used as a data communication antenna.

[0115] Specifically, the antenna 20 according to Embodiment 2 can constitute a 920 megahertz band power transmitting and receiving antenna with the loop antenna 50, and a 2.4 gigahertz band data communication antenna with the inverted F antenna 60. However, the bandwidth of each antenna is not limited to this example. For example, the loop antenna 50 may provide a 900 megahertz band power receiving antenna, and the inverted F antenna 60 may provide a 5.6 gigahertz band data communication antenna.

[0116] The antenna 20 exemplified in Figures 32(A) and (B) allows the use of two different types of antennas 50 and 60, thereby broadening the range of applications and contributing to reducing the antenna design burden on the user. In particular, antenna 20 is suitable for applications based on wireless power transmission. Wireless sensor networks require both a power receiving antenna and a data communication antenna. For example, in IoT sensing using wireless power transfer, it is sometimes necessary to simultaneously utilize two bandwidths: a 920 MHz bandwidth for wireless power transfer and a 2.4 GHz bandwidth for data communication. The antennas exemplified in Figures 32(A) and (B) can provide both of these antennas, making them suitable for application in this field.

[0117] Furthermore, the antenna 20 according to Example 2 allows for the integration of these two antennas into a compact design, thus enabling miniaturization of the antenna, rectenna, and / or module. This allows for broad application in various fields. For example, the antenna 20 illustrated in Figures 32(A) and (B) has a first conductive plate 21 and a second conductive plate 22, each having a predetermined width dimension W3 and a predetermined longitudinal dimension L3, respectively, and securing a predetermined area A3 in two dimensions. This area A3 makes it possible to mount electronic circuits and the like on the surface of the first conductive plate 21.

[0118] For example, a printed circuit board (PCB) may be mounted on the surface of the first conductive plate 21. A PCB is a type of circuit board in which electronic components are attached to a printed wiring board (PWB) to enable it to function as an electronic circuit. The specific configuration of the electronic circuit can be arbitrarily selected depending on the embodiment. For example, the electronic circuit may include, but is not limited to, a power receiving circuit, a power storage circuit, a sensor, a power storage device, and a microcontroller (MCU).

[0119] The antenna 20 illustrated in Figures 32(A) and (B) can be configured as a dual-band antenna (or multi-band antenna) and can be used in any location. In particular, even when the conductive plate 22 is installed on a metal surface or conductive material, the antenna 20 can be configured as a loop antenna in which current flows in a loop shape in the space between the conductive plate 21 and the conductive plate 22, and the reception efficiency does not decrease significantly. Therefore, the antenna 20 can be easily installed on the surface of metal surfaces or conductive equipment and sensors, greatly improving its usability. The basic structure of antenna 20 has been conceptually illustrated with reference to Figures 32(A) and (B).

[0120] Figures 34(A) and (B) show examples of antenna implementation according to Example 2. Figures 34(A) and (B) provide a more specific example of the electronic circuit layer 44 (see Figure 33) located above the first conductive plate 21. The configurations illustrated in Figures 32(A) and (B) and those illustrated in Figures 34(A) and (B) do not necessarily have to correspond strictly. For example, depending on the three-dimensional shape of the electronic circuit, the coverlay 45 illustrated in Figure 33 can be partially omitted. Also, the electronic circuit may be arranged not only on the top surface of the first conductive plate 21, but also utilizing a part of the third conductive plate 23 and / or the second conductive plate 22 (not shown). The coverlay 45 and other components will be explained later.

[0121] The antenna 20 illustrated in Figure 34(A) can be made relatively small due to the wavelength shortening effect when a core material is inserted, and can be, for example, small enough to fit in an adult's hand. The core material and other components will be explained later. For example, the antenna 20 can have a length L3 of approximately 40 mm to 60 mm, as illustrated in Figure 32(A). Furthermore, the antenna 20 can have a thickness of several millimeters for each conductive plate, or a thickness of approximately 5 mm to 8 mm. However, the dimensions of the antenna 20 are not limited to the numerical ranges shown as examples.

[0122] In Figures 34(A) and (B), the electronic circuit mounted on the antenna 20 can include, for example, a power supply, a sensor drive circuit, and / or a wireless communication circuit. When configuring antenna 20 as a dual-band antenna, it is conceivable to receive the power supply voltage from loop antenna 50 (e.g., 920MHz) and transmit the data acquired by the sensor via radio waves from inverted F antenna 60 (e.g., 2.4GHz). In this case, the connection must be made with wires. Thus, if a PCB (electronic circuit) is placed on top of antenna 20, an increase in the height dimension due to the thickness of the PCB can be expected.

[0123] Therefore, when constructing the antenna 20, a flexible printed circuit board (FPC) can be used instead of the PCB mentioned above. FPCs are flexible and can be formed, for example, using a thin insulating material (plastic film). For example, the antenna 20 may be constructed using a two-layer FPC. The first layer can be a 920MHz band antenna (loop antenna 50), and the second layer can be configured as a rectifier circuit, power supply, sensor control circuit, wireless communication circuit, and 2.4GHz band antenna (inverted F antenna 60). It is preferable to use a PCB or FPC to construct a relatively small and low-profile (low-height) antenna 20.

[0124] Next, we will describe the internal shape of antenna 20. In Example 1, as illustrated in Figure 11, the first conductive plate 10a, the second conductive plate 10b, and the third conductive plate 10c were configured in a roughly U-shape in cross-section, with a hollow interior. This offered advantages in terms of reducing product weight, the number of parts, product cost, and the effort required for product processing. Similarly, in Example 2, as illustrated in Figures 32(A) and (B), the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 are configured in a roughly U-shape in cross-section, and their interiors can be made hollow. In this case, similarly, there are advantages in terms of reducing the weight of the product and ensuring the performance of the loop antenna 50.

[0125] In this case, if the internal shape of the antenna 20 is hollow, it is advisable to fix the distance between the two parallel conductive plates 21 and 22 to maintain the shape of the product and ensure its strength. Therefore, in Example 2, a rigid core material 30 made of dielectric material is inserted between two parallel conductive plates 21 and 22 to improve the shape and strength of the product, as well as to miniaturize the loop antenna 50 by shortening the wavelength.

[0126] Referring to Figures 32(C) and (D), an example of a core material 30 that can be inserted into the antenna shape illustrated in Figures 32(A) and (B) is shown. The core material 30 can have an external shape that corresponds to the internal shape of the antenna 20. For example, the antenna 20 illustrated in Figure 32(A) is formed as a roughly rectangular parallelepiped and has a predetermined width dimension W3, a length dimension L3, and a height dimension H3. The core material 30 illustrated in Figure 32(C) similarly has its main body 31 formed into a substantially rectangular parallelepiped as a whole, and has a predetermined width dimension W4, a length dimension L4, and a height dimension H4.

[0127] The dimensions W4, L4, and H4 of the core material 30 can be arbitrarily determined so that the core material 40 can be filled inside the antenna 20. Generally, if the dielectric constant (ε, epsilon) of the core material 30 is high, the dimensions of the antenna 20 (any of W3, L3, and H3) can be shortened due to the wavelength shortening effect, compared to when the core material 30 is not used, making it possible to miniaturize the antenna 20. This miniaturization effect is not limited to dual-band antennas, but is also true for antennas 20 configured as single-band antennas. Furthermore, the main body 31 of the core material 30 does not need to be provided throughout the entire internal shape of the antenna 20. If necessary, the core material 30 may be filled only in a portion of the internal shape of the antenna 20.

[0128] Furthermore, the main body 31 of the core material 30 is not limited to being solid. If necessary, the main body 31 can be perforated. If necessary, a hollow space may be provided inside the main body 31. Providing a hollow space allows the overall structure to be made lighter and improves the power reception efficiency, i.e., the radiation efficiency. Moreover, by designing the shape of the hollow space, making the central part wider and the tip of the antenna narrower, efficiency can be improved. Furthermore, the main body 31 of the core material 30 is not limited to a single component. It may be composed of two or more components as needed.

[0129] The core material 30 is preferably a dielectric material. For example, the core material 30 can be constructed using plastic. Plastic is a type of dielectric material. Plastic is a malleable organic polymer substance and is sometimes called synthetic resin. Because plastic is easy to process into complex shapes and is inexpensive, it is a material that is advantageous for mass production.

[0130] More preferably, the core material 30 can be made of acrylic. Acrylic is a type of plastic, including acrylic resin and acrylic fibers. It is sometimes called acrylic glass. Acrylic is not only highly transparent and aesthetically pleasing, but it is also a relatively hard material. Although acrylic is considered to be relatively weak against impact, its impact resistance can be increased by increasing the thickness of the acrylic.

[0131] Alternatively, the core material 30 can be constructed using polycarbonate. Polycarbonate is a type of plastic, and in particular, a material made from polycarbonate resin. Alternatively, the core material 30 can be constructed using polytetrafluoroethylene (PTFE; fluororesin). For example, the core material 30 can be constructed using Teflon®. Furthermore, the core material is not limited to plastics, acrylics, polycarbonates, PTFE, etc., and other materials with a high dielectric constant can be used. Furthermore, because Teflon® has low dielectric loss, using Teflon® compared to other core materials improves radiation efficiency.

[0132] Therefore, the strength of the antenna 20 can be improved by configuring it so that the conductive plates 21, 22, and 23 are wrapped around the core material 30. For example, the antenna 20 may be configured so that the FPC is wrapped around the core material 30. Because the FPC is flexible, it facilitates wrapping around the core material 30, which is composed of curved surfaces as well as flat surfaces.

[0133] By forming the antenna 20 uniformly in the width direction, production efficiency can be increased when manufacturing a large number of antennas 20, as illustrated in Figure 41. For example, multiple sets of antennas and circuit boards can be molded in parallel on an FPC (see three reference numerals 20, both solid and dashed), the FPC on which these sets of antennas and circuit boards are mounted can be wrapped around a long core material, and then the FPC can be cut along with the core material for each set of antennas and circuit boards (see one reference numeral 20, both solid), thereby enabling the efficient manufacture of multiple antennas 20.

[0134] The core material 30 may be processed separately from the substantially rectangular antenna 20, which consists of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23, and then inserted into the antenna 20 and bonded together. For example, epoxy resin adhesive can be used as the adhesive. In addition, the core material 30 may be injection molded or otherwise manufactured in any manner.

[0135] In this way, by inserting the core material 30 between two conductive plates 21 and 22 that are spaced apart from each other, the maintenance of the product's shape and the securing of the product's strength are improved. Furthermore, by inserting the core material 30 inside the antenna 20, the size of the loop antenna 50 can be reduced due to the wavelength shortening effect based on the dielectric properties of the core material. However, inserting the core material 30 inside the antenna 20 may reduce the power reception efficiency of the loop antenna 50 due to dielectric loss caused by the material.

[0136] Therefore, when using a core material 30 inside the antenna 20, it is preferable to use a material with the lowest possible dielectric loss in order to avoid a decrease in the functionality of the loop antenna 50 and the inverted F antenna 60. For example, the above-mentioned plastics, acrylics, polycarbonates, PTFE, etc. can be used as the material for the core material 30. However, it is possible to use a core material 30 made of a different material. In particular, a material with a relatively high dielectric constant and low dielectric loss is preferred.

[0137] Figure 33 is an example of a diagram showing the cross-sectional configuration of the side surface 26 of the first conductive plate 21 in Figure 32(B). As can be seen from Figure 33, the first conductive plate 21 has a multilayer structure consisting of multiple layers 41 to 45, for example, a two-layer FPC. A two-layer FPC means that there are two layers of copper foil used in the circuit. The multilayer structure of the first conductive plate 21 is not limited to the five layers exemplified. It is possible to have a smaller or larger number of layers. The second conductive plate 22 and the third conductive plate 23 can also have a multilayer structure, but their configurations can differ from those of the first conductive plate 21.

[0138] For example, the bottommost layer 41 of the first conductive plate 21 is a coverlay. A coverlay is equivalent to a protective layer. The coverlay can be formed from any material to provide electrical, mechanical, chemical and / or thermal protection to its surroundings. For example, the second-to-last layer 42 of the first conductive plate 21 is a conductive layer. This conductive layer is formed of, for example, copper foil. The copper foil is used to form the first conductive plate 21 and to construct a loop antenna.

[0139] For example, the third layer 43 from the bottom of the first conductive plate 21 is an insulating layer. The insulating layer is formed from a material with particularly excellent electrical insulation properties, preferably polyimide. For example, the fourth layer 44 from the bottom of the first conductive plate 21 is a conductive layer. This conductive layer is formed of, for example, copper foil. An electronic circuit is formed from this copper foil, or an electronic circuit, battery, sensor, etc., separately molded into this copper foil is electrically connected to it. Furthermore, an inverted F antenna 60 can be molded from the copper foil of layer 44 in a manner that connects to this electronic circuit. For example, the fifth layer 45 from the bottom of the first conductive plate 21 is a coverlay. The materials of layers 42 and 44 are not limited to copper, but may be other conductive materials.

[0140] Furthermore, by using a multi-layered flexible printed circuit board (FPC) in addition to the five-layer FPC shown in Figure 33, it becomes possible to form more complex electronic circuits on the conductive board 21. In addition, by increasing the number of layers, a ground layer can be provided, and interference can be further suppressed by separating the antenna ground from the circuit ground. In this way, the antenna 20 of this embodiment can be easily manufactured by integrally molding the conductive plates 21, 23, and 22, the inverted F antenna 60, and the circuit using an FPC, and then winding them onto a core material to form a dual antenna having a loop antenna 50 and an inverted F antenna 60.

[0141] The layer 44 of the electronic circuit, which is positioned above the first conductive plate 21, and the layer 42 of the loop antenna 50, which is positioned below it, are insulated from each other by an insulating layer 43, except for some contact points. Therefore, even if an electronic circuit is stacked above the first conductive plate 21, the function of the loop antenna 50 formed by the same first conductive plate 21 is not impaired. Furthermore, a loop antenna 50 is formed with the copper foil of layer 42 of the two-layer FPC, and an inverted F antenna 60 is formed with the copper foil of layer 44. Since the two are insulated from each other by the polyimide layer 43, each antenna can be driven independently, and the performance of each antenna is maintained.

[0142] Although layer 43 provides insulation between layer 42 and layer 44, it is possible that high-frequency components may pass through. However, as mentioned above, the inverted F antenna 60 is made up of the second conductive layer of the FPC in the multilayer structure and is placed in a hollow space 24 created by cutting out a part of layer 42. Therefore, since the inverted F antenna 60 is placed in a location with low current density, interference between the loop antenna 50 and the inverted F antenna 60 is suppressed.

[0143] Furthermore, the loop antenna 50 is positioned inside the antenna 20 (see reference numeral 50 in Figure 32(A)). In other words, although the antenna 20 has a roughly U-shaped cross-section, the electric field of the loop antenna 50 is generated inside that U-shape (roughly a C-shape or U-shape). Figure 43 is an example of a diagram showing the simulation results of the electric field of antenna 20. As can be seen from the figure, a vertical electric field is generated between the conductive plates 21 and 22. Here, the loop antenna 50 can be protected from the external environment by the protective layer 45. For this reason, the antennas exemplified in Figures 32(A) and (B) will not have their function impaired regardless of the material of the mounting surface, even if, for example, the first conductive plate 21 is placed on top and the second conductive plate 22 is placed on the bottom. The same applies when the orientation is reversed.

[0144] Furthermore, to configure a completely wireless sensor module, it is desirable that not only the power supply but also the data communication portion for transmitting sensor data be configured wirelessly. When a PCB is installed on one side of the antenna to handle power supply, sensor drive, and wireless communication, the antenna for wireless communication can be configured as a pattern antenna on the PCB. However, when a pattern antenna for an electronic circuit is constructed on the first conductive plate 21, it takes up a large area in the two-dimensional direction.

[0145] In contrast, the antenna 20 according to Embodiment 2 achieves miniaturization of the entire antenna by configuring a loop antenna 50 along the sides of the conductive plates 21, 22, and 23 which extend in a roughly U-shape, and by using a portion of the conductive plates 21, 22, and 23 to configure an antenna for the data communication bandwidth (for example, an inverted F-type antenna 60). As a result, a pattern antenna on the same plane as the circuit board is not required, making it possible to utilize a wider area of ​​the upper surface of the first conductive plate 21.

[0146] As shown in the antenna implementation examples in Figures 34(A) and (B), various implementations are possible for the antenna 50, for example, a 920 megahertz band antenna for wireless power transfer, and the antenna 60, for example, a 2.4 gigahertz band antenna for data communication. For example, referring to Figure 34(B), a hollow space 24 is provided on the surface of the first conductive plate 21 of the antenna 20, and the inverted F-type antenna 60 is placed inside it. For example, Figures 34(A) and (B) show implementations corresponding to Figure 32. Referring to these, a hollow space 24 is defined in the third conductive plate 23 of the antenna 20, and an inverted F-type antenna 60 is placed within it. In either case, it is possible to provide an electronic circuit (PCB or FPC) on the upper surface of the first conductive plate 21 while keeping the size of the antenna 20 small. In particular, when the antenna is integrated into a single FPC, it becomes possible to miniaturize the antenna 20 and reduce the assembly time.

[0147] Next, we will describe a modified example of the loop antenna 50 of antenna 20. Figure 35 shows an example of an antenna modification and an example of a diagram illustrating the core material that can be applied thereto. The shape of the loop antenna 50 is based on the external shape of the conductive plates, which consist of a first conductive plate 21, a second conductive plate 22, and a third conductive plate 23. In the example shown in Figures 32(A) and (B), the first conductive plate 21 and the second conductive plate 22 extend approximately parallel to each other and are connected at their ends by the third conductive plate 23 at an angle of approximately 90 degrees. The performance of the loop antenna may be affected by this shape. In contrast, in the example shown in Figures 35(A) and (B), the first conductive plate 21 and the second conductive plate 22 are connected at their ends by the third conductive plate 23 at an angle greater than 90 degrees and with a greater number of angles.

[0148] Specifically, in the embodiments illustrated in Figures 35(A) and (B), the third conductive plate 23 is bent into a polygonal shape, as illustrated by reference numerals 26 and 27. At the opposite end, the first conductive plate 21 and the second conductive plate 22 are similarly bent into a polygonal shape, as illustrated by reference numerals 28 and 29. As a result, the antenna 20 as a whole has a body that is approximately octagonal in cross-section. Therefore, the shape of the loop antenna 50 has been changed from the roughly rectangular shape exemplified in Figures 32(A) and (B) to the roughly octagonal shape exemplified in Figures 35(A) and (B). By making the shape of the loop antenna 50 closer to a circular (or elliptical) shape, it is possible to broaden the range of design possibilities and improve the performance of the antenna.

[0149] Referring again to Figures 34(A) and (B), the first conductive plate 21 and the second conductive plate 22 extend approximately parallel to each other and are connected at their ends by the third conductive plate 23 in a curved (or arc-shaped) manner. In this case, by making the external shape of the loop antenna 50 even closer to a circular (or elliptical) shape, it is possible to broaden the range of design possibilities and improve the performance of the antenna. In this case, the third conductive plate 23 may extend in an overall curved shape (arc shape). Alternatively, as illustrated particularly in Figures 34(A) and (B), the third conductive plate 23 may extend in a partially curved shape at both ends and partially straight in the center.

[0150] Since an electronic circuit is installed on the upper surface of the first conductive plate 21, it is preferable that its surface be flat. Also, since the bottom surface of the second conductive plate 22 is used as the mounting surface for the antenna 20, it is preferable that its surface be flat. On the other hand, the third conductive plate 23 has a relatively high degree of freedom in terms of shape, so the shape of the loop antenna 50 can be changed by modifying its shape. Thus, depending on the embodiment, the third conductive plate 23 can have any shape so as to ensure suitable performance of the loop antenna 50. For example, the third conductive plate 23 may extend in a straight line overall, as illustrated in Figures 32(A) and (B); it may extend in a curved shape overall or in part, as illustrated in Figures 34(A) and (B); or it may extend in a polygonal shape overall, as illustrated in Figures 35(A) and (B).

[0151] When filling the inside of the antenna 20 with core material 30, the shapes of each conductive plate 21, 22, and 23 may be modified to enhance their holding effect. For example, as illustrated in Figures 35(A) and (B), the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 have an overall approximately octagonal shape. In this case, the third conductive plate 23 is bent in multiple stages (see reference numerals 26 and 27). Correspondingly, the ends of the first conductive plate 21 and the second conductive plate 22 are folded inward (see reference numerals 28 and 29).

[0152] It is preferable that the core material 30 housed inside the antenna 20 also has an external shape of its main body 31 that matches the internal shape of the antenna 20. For example, as illustrated in Figures 35(C) and (D), the main body 31 of the core material 30 may have chamfered edges on each corner (see numbers 36, 37, 38, and 39). The holding force of the core material may be increased by making the antenna 20 and the main body 31 of the core material 30 polygonal in cross-section. Furthermore, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 may be provided with protrusions or recesses at arbitrary locations, and correspondingly, recesses or protrusions may be provided on the main body 31 of the core material 30, thereby locking the core material in place and increasing the holding force of the core material.

[0153] Next, we will describe a modified version of the inverted F antenna 60. Figures 36(A) to (D) show modified examples of the inverted F antenna 60 illustrated in Figures 32(A) and (B). As illustrated in Figure 36(A), the inverted F antenna 60 mainly consists of a feed line 61, a shorting line 62, and a main body 63. The feed line 61, the shorting line 62, and the main body 63 can each be adjusted in terms of thickness, length, position, shape, etc., according to the embodiment. For example, the thickness of the power supply line 61, the short-circuit line 62, and the main body 63 may be adjusted. For example, the length of the main body 63 may be adjusted. For example, the height of the main body 63 may be adjusted. For example, the relative position of the short-circuit line 62 with respect to the power supply line 61 may be adjusted.

[0154] Furthermore, the shape of the main body 63 of the inverted F-type antenna 60 can be adjusted according to the embodiment. For example, as illustrated in Figure 36(A), the inverted F-type antenna 60 can be configured with a main body 63 in a simple linear shape (monopole antenna shape). For example, as illustrated in Figure 36(B), the inverted F-type antenna 60 can be configured such that, instead of configuring the main body 63 in a simple linear shape, it is bent inward by approximately 90 degrees from the state shown in Figure 36(A) (see reference numeral 64). For example, as illustrated in Figure 36(C), the inverted F-type antenna 60 can be configured by further bending the main body 63 inward by approximately 90 degrees from the state shown in Figure 36(B) (see reference numeral 65).

[0155] Furthermore, instead of configuring the main body 63 of the inverted F-type antenna 60 in a simple linear shape, the main body 63 can be configured to be bent into a meander line shape (not shown). In this way, the inverted F antenna 60 allows the main body 63 to be adjusted to various shapes. The main body 63 may be extended straight, be bent inward once or multiple times, or bent inward and outward once or multiple times (for example, bent into a meander shape). The angle at which the main body 63 is bent is not limited to 90 degrees.

[0156] Furthermore, the inverted F-type antenna 60 can be installed at any location on the antenna 20. Referring to Figures 34(A), (B), 36(A)-(C), etc., the inverted F-type antenna 60 is positioned in a hollow space 24 provided on the side (third conductive plate 23) of the rectangular antenna shape. Referring to Figure 36(D), etc., the inverted F antenna 60 is positioned in a hollow space 24 provided on the upper surface (first conductive plate 21) of the rectangular antenna shape.

[0157] Furthermore, the inverted F-type antenna 60 may be placed in a hollow space provided at the bottom surface (second conductive plate 22) of the rectangular antenna shape (not shown). Furthermore, the inverted F-type antenna 60 may be similarly positioned on any face of the antenna 20 when it is formed as a polyhedron with more sides than a rectangular parallelepiped. In the embodiment illustrated, the hollow space 24 has the shape of a rectangular frame. However, the hollow space 24 is not limited to a rectangular shape and can have any shape as long as an inverted F antenna can be mounted therein and the characteristics of the loop antenna 50 can be maintained.

[0158] Furthermore, instead of installing an inverted F-type antenna 60 at any location, a chip antenna may be installed for antenna 20 (not shown). A chip antenna is a chip-type component that has the function of transmitting and receiving the required frequency signals, and can be made particularly small and thin. In this case, the antenna 20 according to Embodiment 2 can be configured as a dual-band antenna including a loop antenna 50 and a tip antenna. Furthermore, instead of the inverted F antenna 60 or the tip antenna, antenna 20 can also be replaced with any other antenna of any shape that has similar characteristics.

[0159] Thus, the inverted F antenna 60 or chip antenna can be attached to any location on the side or top surface of the antenna 20. However, preferably, the top surface of the antenna 20 needs to have space for the electronic circuit (PCB or FPC) as described above. For this reason, when attaching the inverted F antenna to the top surface of the antenna 20, the size of the top surface may be made larger compared to when it is attached to the side. For example, referring to Figure 36(C), almost the entire upper surface of a rectangular antenna shape with dimensions of length L3, width W3, and height H3 (see area A3) is reserved as the installation area for the electronic circuit. In this case, the area of ​​A3 can be approximated as L3 × W3.

[0160] Furthermore, referring to Figure 36(D), when an inverted F-type antenna or a chip antenna is attached to the top surface of a rectangular antenna shape, the rectangular antenna shape is made more elongated in order to secure the installation area for the electronic circuit (see area A5). For example, the rectangular antenna shape has dimensions of length L5, width W5, and height H5, but compared to the above length L3, width W3, and height H3, the value of L3 is increased to L5. The value of width W3 may also be increased to W5. Preferably, the value of A5 is approximately the same as the value of A3.

[0161] The antenna 20 according to Embodiment 2 preferably has a body that is substantially rectangular in shape, and its cross-sectional shape is substantially U-shaped. This substantially U-shaped shape may include any configuration in which the first conductive plate 21 and the second conductive plate 22 are connected by the third conductive plate 23. Preferably, this substantially U-shaped configuration includes a straight configuration of the third conductive plate 23 connecting the first conductive plate 21 and the second conductive plate 22 (see Figure 32(A)), a substantially polygonal configuration (see Figure 35(A)), and a substantially curved (arc-shaped) configuration (see Figure 34(A)).

[0162] However, the shape of the antenna 20 according to Example 2 is not limited to a substantially rectangular parallelepiped shape. For example, the antenna 20 can be configured in a spherical shape, similar to the antenna 1f in Embodiment 1 illustrated in Figure 21. For example, the antenna 20 can be configured in a columnar shape, similar to the antenna 1f in Embodiment 1 illustrated in Figure 24. For example, the antenna 20 can also be configured in any shape, such as a polyhedron, triangular prism, polygonal prism, cylinder, or elliptical prism.

[0163] As described above, the antenna 20 according to Embodiment 2 uses a first conductive plate 21, a second conductive plate 22, and a third conductive plate 23 to form a loop antenna 50. In this case, it is preferable that the upper surfaces of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 are configured to be substantially plate-shaped. However, the shape of the antenna 20 in Example 2 is not limited to this shape. For example, the antenna 20 can also be configured in the same way as the antenna 1e according to Embodiment 1 illustrated in Figure 14(e), by providing slots in the first conductive plate 10a and / or the second conductive plate 10b. In this case, as illustrated in Figure 18, it is also possible to include a slot antenna 18d formed by a slot provided in the first conductive plate 10a and / or a slot antenna 18e formed by a slot provided in the second conductive plate 10b.

[0164] The basic configuration of the antenna 20 according to Example 2 has been described above with reference to Figures 32 to 36. The antenna 20 according to Embodiment 2 is configured as a dual-band antenna and preferably includes a loop antenna 50 and an inverted F antenna 60. In this case, it is preferable that the loop antenna 50 can be configured as a power receiving antenna for a first frequency (e.g., 920 MHz), and the inverted F antenna 60 can be configured as a data communication antenna for a second frequency (e.g., 2.4 GHz).

[0165] However, the antenna 20 may be configured as a dual-band antenna including a loop antenna 50 and a tip antenna. Furthermore, the antenna 20 according to Example 2 can also be configured as a single-band antenna. In this case, the antenna 20 may be configured to include only the loop antenna 50.

[0166] Furthermore, the antenna 20 according to Embodiment 2 may be configured as a multi-band antenna to simultaneously achieve three or more bands. For example, slot antennas 18d, 18e, etc. may be added to the loop antenna 50 and the inverted F antenna 60. Alternatively, other loop antennas may be added to the loop antenna 50 and the inverted F antenna 60. Alternatively, linear antennas such as monopole antennas or dipole antennas may be added to the loop antenna 50 and the inverted F antenna 60.

[0167] Thus, the antenna 20 according to Embodiment 2 is capable of receiving one or more frequency bands and can be configured as an antenna, rectenna, or circuit module (for example, an antenna module or a sensor module, etc.). Next, referring to Figures 37 and 38, we will describe an implementation example in which the antenna 20 is used to supply power to a sensor and operate it.

[0168] Figure 37 shows an example of an implementation in which power is supplied to a sensor using the antenna according to Example 2. The left side shows a transmitter 70 with transmission capabilities enclosed by a dotted line, and the right side shows a receiver 80 with reception capabilities enclosed by a dotted line. The transmitter 70 and receiver 80 are spaced apart from each other at a predetermined distance. For example, the transmitter 70 and receiver 80 are spaced approximately 1 meter apart from each other. In this example, assuming a transmission-to-transmitter distance of 1m, we anticipate charging at approximately 1mW to 3mW, or 1mW to 2mW. However, this numerical range is merely illustrative.

[0169] The transmitter 70 functions as a power-transmitting device during wireless power supply. The oscillator 71 oscillates a signal at a predetermined frequency. This signal may be amplified as needed to remove unwanted frequency components. Subsequently, the transmitting antenna 72 radiates radio waves to the outside. The transmitting antenna 72 is controlled by a microcontroller (controller) 73. The microcontroller (controller) 73 controls the transmission of the transmitting antenna 2 based on a feedback signal from the data transceiver 74, which is based on data received via the data transmission antenna 75.

[0170] The receiver 80 functions as the receiving device during wireless power transfer. The antenna 20 illustrated in Figures 32 to 36 can be used as this receiver 80. The receiving antenna 81 (for example, the loop antenna 50 of antenna 20) receives the power supply microwaves transmitted externally from the transmitting antenna 72. For example, the loop antenna 50 can function as a 920 MHz band power receiving antenna. The rectifier 82 (for example, part of the PCB or FPC) rectifies the received radio waves and converts them into a rectified voltage. The power management unit 83 (for example, part of the PCB or FPC) controls the charging voltage based on the rectified voltage. The charging voltage charges a battery, for example, that is mounted on part of the PCB or FPC.

[0171] The receiving function, consisting of a rectifier circuit 82 and a power management unit 83, is controlled by a microcontroller 85 mounted on part of the PCB or FPC to charge the battery 84 and to drive any sensor 86 with the received power. It is also possible to drive the sensor 86 with the power of the battery 84. The sensor 86 may be circuit-shaped as part of the PCB or FPC. Alternatively, the sensor 86 may be connected externally to the PCB or FPC. The type of sensor 86 is arbitrary, but for example, a thermal sensor, temperature sensor, light sensor, humidity sensor, vibration sensor, etc. can be used.

[0172] The status of the power management unit 83, the status of the sensor 86, and the information acquired by the sensor 86 are continuously or intermittently monitored by the microcontroller 85. Signals indicating these statuses and the information acquired by the sensor 86 are transmitted by the data transmitter 87 to an external transmitter 70 via the transmitting / receiving antenna 88 (for example, the inverted F antenna 60 of antenna 20). For example, the inverted F antenna 60 can function as a data communication antenna in the 2.4GHz band. Furthermore, while the power (microwaves) used for wireless power transfer (920MHz) is transmitted in one direction, the radio waves used for data communication (2.4GHz) can be transmitted bidirectionally.

[0173] Thus, the antenna 20 can be modularized and is particularly suitable for configuration as a sensor module. Antenna 20 can support two frequency bands while taking advantage of the benefit of being able to be installed on a metal surface. Therefore, it is less restricted by the material of the installation surface and can be used in various locations, which in particular enables miniaturization of sensor modules.

[0174] Figure 38 is an example of a diagram showing the simulation results of the radio wave efficiency of two antennas. Figure 38 shows the simulation results of the radio wave efficiency of the receiving antenna 20 shown in Figure 39, which is equipped with a 2450MHz (2.45GHz) data antenna and a 918MHz feed antenna, as described later, under the usage conditions illustrated in Figure 37. In Figure 38, the horizontal axis shows frequency, and the vertical axis shows efficiency (1 = 100 percent). The simulation results for the loop antenna 50 are shown at the top of Figure 38, and the simulation results for the inverted F antenna 60 are shown at the bottom. These simulation results correspond to electromagnetic field simulation results under ideal conditions (a situation where there are no obstacles that obstruct energy reception), with the distance from the power source to antenna 1 being 1m as described above.

[0175] Referring to Figure 38, it can be seen that the loop antenna 50 achieves an efficiency of approximately 87 percent at a frequency of 918 MHz (0.918 GHz). Furthermore, it can be seen that the inverted F antenna 60 achieves an efficiency of approximately 83 percent at a frequency of 2.5 GHz.

[0176] Therefore, even when antenna 20 is configured as a dual-band antenna, interference between the antennas and a decrease in efficiency are avoided. In particular, it was confirmed that the characteristics of the 920 MHz band do not deteriorate significantly on the loop antenna 50 side. Also, it was confirmed that the characteristics of the 2.4 GHz band do not deteriorate significantly on the inverted F antenna 60 side. Thus, the antenna 20 of Example 2 realizes a practical power receiving antenna with the loop antenna 50 and a practical data communication antenna with the inverted F antenna 60.

[0177] As described above, antenna 20 is configured as a dual-band antenna with multiple antennas arranged three-dimensionally. In this case, it was confirmed that even when changing from single-band to dual-band, an antenna shape can be obtained in which the characteristics of both antennas are not significantly degraded. Therefore, antenna 20 is expected to achieve overall miniaturization while exhibiting good antenna performance.

[0178] As described above, the antenna 20 according to Embodiment 2 can not only supply the received energy to the sensor 86, but can also transmit energy to any object such as a robot, equipment, or PC. In particular, when applied to FA (Factory Automation), the antenna 20 may be applied to the equipment instead of the sensor 86. Furthermore, it can also be applied to building management, in which case the antenna 20 may be applied to any component used in close proximity to the human body, such as employee ID cards. Furthermore, the targets for power transmission may also include mobile phones, PDAs (personal digital assistants), wireless microphones, wireless USB devices, wireless theater systems, wireless televisions, wireless cameras, wireless headphones, wireless mice, wireless keyboards, wireless routers, wireless printers, and the like.

[0179] Next, with reference to Figures 39 and 40, an implementation example will be described in which the antenna 20 is used to supply power to and operate equipment including a sensor. Figure 39 shows an example of an implementation where an antenna is used to supply power to a sensor placed on a device. Referring to Figure 39, a conceptual example is shown in which an antenna 20 is attached to one side of the device 90, indicated by a dotted line, to enable power supply to a sensor installed on the device 90. This device 90 can be used in place of the sensor 86 illustrated in Figure 38. As described above, the loop antenna 50 of the antenna 20 is formed inside the antenna 20, so that the performance of the antenna is not impaired by the material of the mounting surface. For this reason, even if the antenna 20 is directly attached to the metal surface of the equipment 90, the loop antenna 50 can continue to function.

[0180] In this case as well, the antenna 20 is a power transmitting antenna for a first frequency (e.g., 918 MHz) formed by a loop antenna 50 consisting of a first conductive plate 21, a second conductive plate 22, and a third conductive plate 23. For example, the loop antenna 50 enables power supply to the equipment 90. Furthermore, the antenna 20, with the inverted F-type antenna 60, constitutes a data communication antenna for a second frequency (e.g., 2.45G). For example, the inverted F-type antenna 60 enables the transmission of information indicating the status of the device 90 and information measured by sensors to the outside.

[0181] Figure 40 is an example of a figure showing the simulation results of the received signal strength of two antennas. Figures 40(A) and (B) show the simulation results for the power reception status of each antenna in three-dimensional space, with the x-axis of the device 90 in Figure 39 facing upwards and the yz-plane facing downwards (i.e., the device 90 in Figure 39 rotated 90 degrees clockwise around the y-axis). These simulation results correspond to electromagnetic field simulation results under ideal conditions (a situation where there are no obstacles obstructing energy reception), with a distance of 1m from the power source to the antenna 20. Figure 40(A) shows that the darker the color (closer to black than gray), the better the power reception. As can be seen from this figure, it was confirmed that the loop antenna 50 is able to receive energy relatively evenly along the entire length of the antenna 20, which is composed of conductive plates 21, 22, and 23.

[0182] Referring to Figure 40(B), the simulation results for the power reception of the inverted F antenna 60 in three-dimensional space are shown. Note that these simulation results correspond to electromagnetic field simulation results under ideal conditions (a situation where there are no obstacles obstructing energy reception), with a distance of 1m from the power source to the antenna 20. Similarly, Figure 40(B) shows that the darker the color (closer to black than gray), the more favorable the power reception. As can be seen from this figure, although the inverted F-type antenna 60 is biased towards one end of the antenna 20, and therefore biased towards one end of its entire length, it was confirmed that it can transmit and receive energy over the entire area of ​​the device 90. Furthermore, estimations of the received power of the antenna used in this simulation showed that, under conditions of a power transmission output of 1W and a transmission distance of 1m, it was possible to supply approximately 7.26mW and -21.39dB of power, and it was estimated that approximately 3.5mW of power could be charged to the battery. However, please understand that these figures are merely examples and not limiting.

[0183] Thus, by combining antenna patterns for two frequency bands, antenna 20 realizes a dual-band antenna consisting of a loop antenna 50 (e.g., 918 MHz) and an inverted F antenna 60 (e.g., 2.45 GHz). Furthermore, antenna 20 can be configured not only as a dual-band antenna but also to transmit and receive radio waves at even more frequencies, making it a multi-band antenna with three or more bands.

[0184] As described above, the antenna 20 according to Embodiment 2 integrates two frequency antennas, a loop antenna 50 and an inverted F-type antenna 60. Although these two antennas are configured as a single unit, they function in such a way that the performance of each antenna is not significantly impaired during use. Furthermore, the dual-band antenna of this embodiment, which combines the loop antenna 50 and the inverted F antenna 60, may have higher reception efficiency than using either the loop antenna 50 or the inverted F antenna 60 alone, for the following reasons. The loop antenna 50 shares a common ground with the receiving antenna itself, allowing for a larger antenna size and improved efficiency. Furthermore, the inverted F antenna 60 has a hollow space 24 provided for the loop antenna 50, and the current passes through both sides of the cut-out window, contributing to an improved radiation pattern and a slight increase in radiation efficiency.

[0185] Furthermore, by optimizing the mounting positions of the loop antenna 50 and the inverted F antenna 60, the antenna 20 may reduce the interference between each antenna and suppress a decrease in their respective efficiency. In addition, efficiency can be further improved by adjusting the impedance of each antenna or matching them, for example, to ensure that the efficiency of each antenna is appropriate. For example, a U.FL connector or any matching circuit suitable for use in small devices requiring high-frequency transmission may be used. The inverted F antenna 60 can be placed far from the feeder 25 to reduce interference. Furthermore, placing it at a position where the current of the receiving antenna 50 is small (at the node of the λ / 4 resonance) can also reduce interference.

[0186] The antenna 20 according to Example 2 has been described above with reference to Figures 32 to 43. The antenna 20 according to Example 2 can be implemented in various ways. Appearance 1 In its simplest implementation, antenna 20 can be configured as an antenna including at least a loop antenna 50. Antenna 20 can be configured as a single-band antenna consisting of a loop antenna 50. Depending on the implementation, the loop antenna 50 may be further combined with a rectifier (or rectifier circuit 82, etc.).

[0187] Appearance 2 The antenna 20 can be implemented in a configuration that includes at least a loop antenna 50 and a rectifier (or rectifier circuit 82), and the antenna impedance can be adjusted to obtain high efficiency. In this case, matching can be provided by varying the dimensions and shape of the antenna 20, as well as by adjusting the frequency.

[0188] Appearance 3 The antenna 20 can be implemented by combining at least a loop antenna 50, a rectifier (or rectifier circuit 82), a power supply circuit (or power management 83), and a data communication circuit board (or microcontroller 85, etc.). In this case, it can be provided as an antenna module.

[0189] Pattern 4 In addition to Example 3, an inverted F-type antenna 60 may be added. In this case, the inverted F-type antenna 60 can be applied to particularly high frequencies, for example, to the 2.4 GHz band. In this case, the antenna pattern portion of the inverted F-type antenna 60 may be adjusted in various ways (see Figures 36(A) to (C)). The mounting position of the inverted F-type antenna 60 may also be adjusted in various ways (see Figures 36(B) and (D)). Various adjustments can be made to ensure that the antenna pattern portion of the inverted F-type antenna 60 takes on a suitable shape.

[0190] Appearance 5 Furthermore, as an implementation configuration for the antenna 20, a sensor network system (or sensor module) may be constructed that includes at least a loop antenna 50, a rectifier (or rectifier circuit 82), a power supply circuit (or power management 83), a data communication circuit board (or microcontroller 85, inverted F antenna 60), and a sensor 86 (see Figure 37). Instead of the sensor 86, equipment 90 or the like may be used (see Figure 39).

[0191] Appearance 6 In each of the five embodiments, a core material 30 may be added inside the antenna 20. In this case, the size, shape, and characteristics of each antenna may be adjusted in various ways by adjusting the material, size, shape, etc. of the core material. In this case, an FPC may be used for the antenna 20.

[0192] As described above, the present invention provides an antenna, rectenna, and circuit module that can receive one or more frequency bands, is compact, low-profile, and has few restrictions on installation location. Therefore, it is possible to provide antenna modules, sensor modules, etc. that can be used in a wide range of compact sensing applications.

[0193] In Example 1, various forms of receiving antennas 1, 1A, and 1a-1h were described with reference to Figures 1-31 and 42. Furthermore, in Example 2, various forms of the receiving antenna 20 were described with reference to Figures 32 to 41 and Figure 43. Examples 1 and 2 may be implemented independently of each other, or they may be implemented in combination. For example, the core material 30 and the inverted F antenna 60 in Example 2 can be applied to the receiving antennas 1, 1A, 1a-1h in Example 1. Similarly, the description of Example 1 is applicable to Example 2.

[0194] Furthermore, the communication bandwidth used for power supply is not limited to the 920MHz band; any UHF band is acceptable, for example. In Europe, the 868MHz band may be used, and in the United States, the 915MHz band may be used. Other frequency bands belonging to the UHF band are also acceptable. Furthermore, the communication bandwidth for data communication is not limited to the 2.4GHz band; a frequency band within a range of ±10% of 2.4GHz may also be used. For example, the 2.45GHz band can be used. Alternatively, a communication bandwidth near 5.7GHz may also be used. While high frequency bandwidths are required for high-speed data communication, lower frequency bandwidths can be used for power supply compared to data communication.

[0195] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations. Furthermore, the above-described embodiments disclose at least the configuration described in the claims. [Explanation of symbols]

[0196] 1, 1A, 1a-1h... Antenna 10a...First conductive plate 10b...Second conductive plate 10c...conductive material 10d...Protrusion 11. Feeder 20... Antenna 21...First conductive plate 22...Second conductive plate 23. Third conductive plate 30... Core material 50... Loop antenna 60... Inverted F-type antenna

Claims

1. A first conductive plate and A second conductive plate facing the first conductive plate, A feeder connecting the first end of the first conductive plate and the second end of the second conductive plate facing the first end, A conductive member connecting the first other end opposite to the first end and the second other end opposite to the second end, A first antenna equipped with, A receiving antenna used for wireless power transfer, equipped with the following features.

2. The power receiving antenna according to claim 1, characterized in that the conductive member is a plate-shaped member that connects the first other end of the first conductive plate and the second other end of the second conductive plate.

3. The receiving antenna according to claim 2, characterized in that the first conductive plate, the second conductive plate, and the plate-shaped conductive member are integrally molded.

4. The receiving antenna according to claim 2, characterized in that the first conductive plate, the second conductive plate, and the plate-shaped conductive member are formed by bending a single conductive plate.

5. The receiving antenna according to claim 4, characterized in that the one conductive plate is formed by cutting out a portion within a predetermined distance from its end.

6. The first conductive plate has a stepped central portion in the longitudinal direction that protrudes toward the second conductive plate, The second conductive plate has a stepped central portion in the longitudinal direction that protrudes toward the first conductive plate. The receiving antenna according to feature 1.

7. The power receiving antenna according to claim 4, characterized in that the plate-shaped conductive plate is configured with a cutout within a predetermined distance from its end.

8. The receiving antenna according to claim 7, characterized in that slots are provided in the first conductive plate and the second conductive plate.

9. The receiving antenna according to claim 8, characterized in that a portion of the first conductive plate protrudes from the widthwise end of the first conductive plate near the center toward the second conductive plate.

10. The receiving antenna according to claim 9, characterized in that a gap is provided between the tip of the protruding portion and the second conductive plate.

11. A power receiving antenna according to any one of claims 1 to 10, wherein a dielectric core material is filled between the first conductive plate and the second conductive plate.

12. A hollow space is provided in at least one of the first conductive plate, the conductive member, and the second conductive plate, and the second antenna is placed in that space. A power receiving antenna according to any one of claims 1 to 10.

13. The first antenna functions as a loop antenna. A power receiving antenna according to any one of claims 1 to 10.

14. The first conductive plate, the conductive member, and the second conductive plate have a substantially U-shaped cross-section, and the electric field of the loop antenna is generated inside the U-shape. The receiving antenna according to claim 13.

15. The first antenna is a power receiving antenna. A power receiving antenna according to any one of claims 1 to 10.

16. The first antenna is driven in the frequency range of approximately 920 MHz. The receiving antenna according to claims 1 to 10.

17. The second antenna is either an inverted F antenna or a tip antenna. The receiving antenna according to claim 12.

18. The aforementioned second antenna is an antenna for transmitting and receiving data. The receiving antenna according to claim 12.

19. The second antenna is driven in the frequency range of approximately 2.4 GHz. The receiving antenna according to claim 12.

20. The receiving antenna according to claim 12, wherein a dielectric core material is filled between the first conductive plate and the second conductive plate.

21. The first conductive plate, the conductive member, and the second conductive plate are made of a first conductive layer of a flexible printed circuit board (FPC), the second antenna is an inverted F-type antenna, and the inverted F-type antenna is made of a second conductive layer of the FPC. The receiving antenna according to claim 12.

22. The first antenna functions as an inverted F antenna. The receiving antenna according to claim 1.

23. The width of the first conductive plate and the width of the second conductive plate are substantially the same. The length of the first conductive plate and the length of the second conductive plate are 10 to 30%, preferably about 20%, longer than the length whose resonant frequency is the frequency band of the radio waves intended for reception. The receiving antenna according to claim 22.

24. The width of the first conductive plate and the width of the second conductive plate are substantially the same. The length of the first conductive plate and the length of the second conductive plate are 10 to 30%, preferably about 20%, shorter than the length whose resonant frequency is the frequency band of the radio waves intended for reception. The receiving antenna according to claim 22.

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