Power reception antenna

Abstract

To provide a power reception antenna capable of efficiently receiving power transmitted from a power transmitter located at a certain distance and capable of accepting a certain range in terms of its size.SOLUTION: A power reception antenna 20 used for wireless power supply includes a first conductive plate 21, a second conductive plate 22 opposite the first conductive plate 21, a feeder 25 connecting a first end of the first conductive plate 21 and a second end of the second conductive plate 22 opposite the first end, and a conductive member 23 connecting a first other end opposite the first end and a second other end opposite the second end.SELECTED DRAWING: Figure 34

Description

[Technical field]

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

[0002] In recent years, wireless power supply has become common, enabling charging and operation of various electronic devices. Patent Documents 1 and 2 disclose configurations of power receiving antennas for wireless power supply. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-025502 A [Patent Document 2] JP 2020-184718 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in recent years, various IoT devices have been developed and used, and many of these IoT devices include those used as various sensor devices. Although such sensor devices are desired to operate for a long time, there is a time limit for operation using a battery. These sensor devices do not require much power for actual operation, and can operate sufficiently with power supplied by wireless power supply. However, it is better to be able to receive transmitted power efficiently, and development of a receiving antenna that can receive power efficiently is desired. In addition, sensors and the like are required to be able to receive power and operate even when transmitted from a distant position. The receiving antenna according to Patent Document 1 has a problem that the transmitting side needs to be placed in a nearby position. In addition, since the receiving antenna is mounted on and used in various devices, there is also a problem that it needs to be adapted to various shapes.

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

[0006] In order to solve the above problems, for example, the configurations described in the claims are adopted. The present application includes multiple means for solving the above problems, and one example is a receiving antenna comprising a first conductive plate, a second conductive plate opposite the first conductive plate, a feeder connecting a first end of the first conductive plate and a second end of the second conductive plate opposite the first end, and a conductive member connecting a first other end opposite the first end and a second other end opposite the second end.

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

[0008] In the above 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 power receiving antenna, the first conductive plate, the second conductive plate, and the plate-shaped conductive member may be configured by bending a single conductive plate.

[0010] The power receiving antenna may be configured such that one conductive plate is cut out within a predetermined distance from an end thereof.

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

[0012] In the above-mentioned power receiving antenna, the plate-shaped conductive plate may be configured with a notch cut out within a predetermined distance from an end portion.

[0013] In the above power receiving antenna, the first conductive plate and the second conductive plate may be provided with a slot.

[0014] In the above power receiving antenna, a protrusion may be provided in which part of the first conductive plate protrudes from an end in the width direction near the center of the first conductive plate toward the second conductive plate.

[0015] In the power receiving antenna, a gap may be provided between a tip of the protrusion and the second conductive plate. Effect of the Invention

[0016] A power receiving antenna used for wireless power feeding according to one embodiment of the present invention can efficiently receive power due to its shape and supply the power to a device or the like to which the power receiving antenna is connected. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an antenna according to the present invention. [Diagram 2] FIG. 2 is an example of a graph showing the transition of the radiation efficiency of the antenna shown in FIG. 1 according to the communication frequency. [Diagram 3] FIG. 3 is an example of a graph showing the transition of S parameters according to the communication frequency of the antenna shown in FIG. [Figure 4] FIG. 4 is an example of a graph showing the transition of radiation efficiency according to communication frequency when the substrate size of the antenna shown in FIG. 1 is changed. [Diagram 5] FIG. 5 is an example of a graph showing the transition of radiation efficiency according to communication frequency for an antenna of a different size from the antenna shown in FIG. [Figure 6] FIG. 6 is an example of a graph showing the transition of S parameters according to the communication frequency for an antenna of a different size from the antenna shown in FIG. [Figure 7] FIG. 7 is an example of a graph showing the transition of each S parameter according to the communication frequency for an antenna of a different size from the antenna shown in FIG. [Figure 8] FIG. 8 is an example of a graph showing the transition of each S parameter in the vertical direction according to the communication frequency for an antenna of a different size from the antenna shown in FIG. [Figure 9] FIG. 9 is an example of a graph showing the transition of radiation efficiency according to communication frequency for an antenna of a different size from the antenna shown in FIG. [Figure 10] FIG. 10 is an example of a graph showing the relationship between the planar size of an antenna and radiation efficiency. [Figure 11] FIG. 11 is a diagram showing an example of an antenna configuration different from that of FIG. [Figure 12] The upper graph in Fig. 12 shows an example of a graph indicating the change in radiation efficiency according to the communication frequency when the antenna height is changed, and the lower graph in Fig. 12 shows an example of a graph indicating the change in radiation efficiency according to the communication frequency when the antenna width is changed. [Figure 13]FIG. 13 is a diagram showing an example of an antenna pattern (directivity) when the height of the antenna is changed. [Figure 14] 14(a) to (f) are diagrams showing examples of configurations of various antennas. [Figure 15] FIG. 15 shows an example of the antenna shown in FIG. 14(f) and a partially enlarged view thereof. [Figure 16] FIG. 16 is an example of a graph showing the transition of the radiation efficiency according to the communication frequency of each of the antennas shown in FIG. [Figure 17] FIG. 17 is a diagram showing an example of the antenna pattern (directivity) of each antenna shown in FIG. [Figure 18] FIG. 18 is a diagram showing an example of the antenna shown in FIG. 14(f) functioning as a composite antenna. [Figure 19] FIG. 19 is an example of a graph showing the radiation efficiency of the antenna according to the communication frequency when the gap between the protruding portion of the antenna and the second conductive plate shown in FIG. 14(f) is changed. [Figure 20] FIG. 20 is a diagram showing an example of the antenna pattern (directivity) of the antenna when the gap between the protruding portion of the antenna and the second conductive plate shown in FIG. 14(f) is changed. [Figure 21] FIG. 21 is a diagram showing an example of a configuration in which the antenna is configured in a spherical shape. [Figure 22] FIG. 22 is an example of a graph showing the radiation efficiency of the antenna shown in FIG. 21 according to the communication frequency. [Figure 23] FIG. 23 is a diagram showing an example of an antenna pattern (directivity) of the antenna shown in FIG. [Figure 24] FIG. 24 is a diagram showing an example of a configuration in which an antenna is configured in a columnar shape. [Diagram 25] FIG. 25 is an example of a graph showing the radiation efficiency of the antenna shown in FIG. 24 according to the communication frequency. [Figure 26] FIG. 26 is a diagram showing an example of an antenna pattern (directivity) of the antenna shown in FIG. [Figure 27]FIG. 27 is a diagram showing an example of the configuration of an antenna when a power receiving circuit is provided on one of the conductive plates. [Figure 28] FIG. 28 is an example of a graph showing the radiation efficiency of the antenna shown in FIG. 27 depending on the communication frequency. [Figure 29] FIG. 29 is a diagram showing an example of an antenna pattern (directivity) of the antenna shown in FIG. [Diagram 30] FIG. 30 is a diagram showing an example of a usage form of the antenna according to this embodiment. [Diagram 31] FIG. 31 is an example of an exploded perspective view of the package shown in FIG. [Diagram 32] FIG. 32 is a diagram showing an example of a basic configuration of an antenna according to the second embodiment and a core material applicable thereto. [Diagram 33] FIG. 33 is a diagram showing an example of a cross-sectional configuration of the first conductive plate in FIG. 32(B). [Diagram 34] FIG. 34 is a diagram illustrating an example of mounting the antenna according to the second embodiment. [Diagram 35] FIG. 35 is an example diagram showing a variation of the antenna and the core material that can be applied therein. [Diagram 36] FIG. 36 is an example diagram showing a modification of the 2.4 GHz antenna. [Figure 37] FIG. 37 is a diagram illustrating an example of implementation in which the antenna according to the second embodiment is used to feed power to a sensor. [Figure 38] FIG. 38 is an example of a diagram showing a simulation result of the radio wave efficiency of two antennas. [Figure 39] FIG. 39 is an example diagram showing an implementation example in which an antenna is used to power a sensor placed in a device. [Diagram 40] FIG. 40 is an example of a diagram showing a simulation result of the receiving strength of two antennas. [Diagram 41] FIG. 41 is an example of a diagram showing a concept of efficiently manufacturing a plurality of antennas. [Diagram 42] FIG. 42 is an example of a graph showing a transition of impedance (Z parameter) according to the communication frequency of the antenna shown in FIG. [Diagram 43] FIG. 43 is a diagram showing an example of a simulation result of the electric field of the antenna. [Diagram 44] FIG. 44 is an example of a diagram showing a concept diagram showing the relationship between frequency and impedance. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a power receiving antenna for wireless power supply (radio power feeding) according to this embodiment will be described with reference to the drawings.

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

[0020] Antenna 1 is a receiving antenna for long-distance wireless power supply, and receives and supplies power for operating various IoT devices. Therefore, antenna 1 may be mounted on or connected to various devices, and it is desirable that it can accommodate as many shapes and sizes as possible. Furthermore, antenna 1 is inductive, and by making feeder 11 (rectifier) ​​capacitive, matching can be achieved without an impedance matching circuit that has losses, and it functions as a highly efficient receiving antenna system. Both the first conductive plate 10a and the second conductive plate 10b are flat thin plates with a length L1 and a width W1. Fig. 1 shows an example in which the width W1 = 15 mm, the length L1 = 40 mm, and the distance between the thin plates H1 = 10 mm.

[0021] 1 shows an example in which the conductive member 10c is rod-shaped, but is not limited to a rod shape and may be a plate-shaped member as long as it can connect the first conductive plate 10a and the second conductive plate 10b. The first conductive plate 10a, the second conductive plate 10b, and the conductive member 10c can be made of any material that allows a current to flow well, such as copper or aluminum.

[0022] The feeder 11 is a so-called power feeder, and is provided at one end of the antenna 1 so as to connect the first conductive plate 10a and the second conductive plate 10b. That is, the feeder 11 is connected to an end of the first conductive plate 10a and an end of the second conductive plate 10b facing the first conductive plate 10a. In FIG. 1, the conductive member 10c is provided at a position closer to the feeder 11, but it is preferable that the conductive member 10c is provided at an end opposite to the end where the feeder 11 is provided. The opposite end here refers to the end opposite to the end of the first conductive plate 10a and the second conductive plate 10b in the longitudinal direction as viewed from the end 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 with reference to FIG. 2 and FIG. 3.

[0023] Fig. 2 shows the radiation efficiency of the antenna 1 when the conductive member 10c is placed at various positions, and shows the radiation efficiency at each frequency. Fig. 3 shows the change in S-parameter at each frequency of the antenna 1. The antenna 1 is used as a power receiving antenna in wireless power supply, and the radiation efficiency is an index indicating how efficiently the power radiated from a radiation source can be received as power.

[0024] The data shown in Fig. 2 and Fig. 3 are obtained when W1 = 30 mm, L1 = 60 mm, and H1 = 10 mm are set for the antenna 1, and the distance d from the center of the antenna 1 in the longitudinal direction to the conductive member 10c is changed. The distance d is set to the positive direction in the direction approaching the feeder 11, and the simulation results are shown for each of the following cases: 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 the antenna 1, and d = -30 is the end position of the first conductive plate 10a (second conductive plate 10b) on the opposite side to the position where the feeder 11 is provided.

[0025] It can be seen from Fig. 2 that the radiation efficiency of the antenna 1 does not depend greatly on the position of the conductive member 10c in the 920 MHz band. In Fig. 2, the horizontal axis represents the communication frequency, and the vertical axis represents the radiation efficiency. Specifically, in the 920 MHz band, the radiation efficiency is 0.92492264 when d=-30, 0.91848839 when d=-23.3333, 0.90653664 when d=-10, 0.89302688 when d=-3.3333, 0.88013362 when d=3.3333, 0.8730083 when d=10, 0.87878139 when d=16.6667, and 0.9007059 when d=10. Thus, it can be seen that in either case, a radiation efficiency of 0.85 or higher can be guaranteed in the 920 MHz band.

[0026] Moreover, except for the case of d=23.3333, the radiation efficiency of the antenna 1 is higher when the conductive member 10c is placed farther away from the feeder 11. These information are values ​​obtained by the applicants through simulation. Among these values, it can be understood that the radiation efficiency when d=-30, that is, when the conductive member 10c is provided on the opposite side of the feeder 11, has a relatively high radiation efficiency among the simulated arrangements. From FIG. 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 where the feeder 11 is provided, in the longitudinal direction.

[0027] FIG. 3 is a graph showing the transition of the S parameter of the antenna 1, more precisely the S11 parameter, for each frequency band according to the arrangement position from the center of the conductive member 10c. In the graph of FIG. 3, the horizontal axis shows the communication frequency, and the vertical axis shows the decibel value. S11 is the input reflection coefficient for the antenna 1. However, the less the reflection, the higher the efficiency, and the lower the decibel value is, the better. However, in the example of FIG. 3, the reflection coefficient for 50 ohms is simulated, and since it is not 50 ohms when matching with the circuit side directly, it is different from the actual value. If the conductive member 10c is brought closer to the feeder 11, the S parameter falls in the 920 MHz band, so it is preferable to place the conductive member 10c as far away from the feeder 11 as possible.

[0028] In addition, in FIG. 3, the value of the S parameter in the 920 MHz band corresponding to each placement position of the conductive member 10c is d=-30, that is, the S11 parameter (sometimes simply referred to as S11) when the conductive member 10c is placed at the position farthest from the feeder 11 is -0.11598898. Similarly, the applicants have obtained through simulations the following information: when d=-23.3333, S11=-0.12124553; when d=-16.6667, S11=-0.13121938; when d=-10, S11=-0.14794466; when d=-3.3333, S11=-0.17484571; when d=3.3333, S11=-0.21969521; when d=10, S11=-0.302915; and when d=16.6667, S11=-0.50750559.

[0029] From this value, it can be seen that d=16.6667 is preferable for antenna 1 in terms of reflectivity; however, in terms of the antenna pattern (antenna directivity), locating conductive member 10c away from feeder 11 makes the antenna pattern closer to omnidirectional. Considering that it is desirable for a receiving antenna to be able to receive power no matter where it is placed relative to the transmitter, it is better for the antenna pattern to be omnidirectional, and in combination with the radiation efficiency, it is preferable for d=-30, that is, for conductive member 10c to be arranged so that the ends of first conductive plate 10a and second conductive plate 10b where feeder 11 is provided connect first conductive plate 10a and second conductive plate 10b at the opposite ends in the longitudinal direction.

[0030] 2 and 3, and the antenna pattern and the use scene of the antenna 1, it is preferable to configure the antenna 1 so that the conductive member 10c connects the first conductive plate 10a and the second conductive plate 10b at the end on the opposite side in the length direction of the first conductive plate 10a and the second conductive plate 10b to the feeder 11. Therefore, it can be said that the antenna 1 is preferably configured such that the first conductive plate 10a and the second conductive plate 10b facing the first conductive plate 10a are separated by a predetermined distance, connected at one end by the feeder 11, and connected at the other end by the conductive member 10c.

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

[0032] As shown in FIG. 4, the best S parameters (highest reception level (decibel value)) were obtained when (W1, L1)=(30mm, 60mm) at the 920 MHz band used for power supply, followed by (W1, L1)=(120mm, 240mm), and the lowest was obtained when (W1, L1)=(60mm, 120mm). However, the values ​​are not substantially different, and it can be said that all of the values ​​are practical. From this, in consideration of the fact that the proportion of the antenna 1 in any device that requires actual power should be as small as possible and that the reception accuracy is the highest, it can be said that the size of the three types of conductive plates (first conductive plate 10a, second conductive plate 10b) shown in FIG. 4 is preferably (W1, L1)=(30mm, 60mm).

[0033] In Fig. 2, Fig. 3, and Fig. 4, the performance was compared when the position of the conductive member 10c was changed and when the sizes of the first conductive plate 10a and the second conductive plate 10b were changed. From here, using Fig. 5 and Fig. 6, the antenna performance when the sizes of the first conductive plate 10a and the second conductive plate 10b are changed and the position of the conductive member 10c is changed will be considered in comparison with Fig. 2 and Fig. 3. That is, the antenna performance will be described when the connection position of the conductive member 10c is changed in an antenna with the same shape as Fig. 1 and W1 = 15 mm, L1 = 40 mm, and H1 = 10 mm. That is, the characteristics of the antenna showing the performance in Fig. 5 and Fig. 6 will be described, which has a smaller area of ​​the first conductive plate 10a and the second conductive plate 10b than the antenna showing the characteristics in Fig. 2 and Fig. 3. In addition, regarding the position of the conductive member 10c, the distance from the center position of the first conductive plate 10a and the second conductive plate 10b is defined as d, the direction approaching the feeder 11 is defined as positive, and the performance will be shown when d=-20, d=-13.3333, d=-6.6667, d=0, d=6.6667, and d=13.3333.

[0034] Fig. 5 is a graph showing the transition of radiation efficiency according to the communication frequency of an antenna of a size different from that of the antenna shown in Fig. 1. As shown in Fig. 5, in the 920 MHz band, the radiation efficiency is highest when d=-20, and it is found that the closer the position of the conductive member 10c is to the feeder 11, the lower the radiation efficiency becomes. More specifically, the radiation efficiency is 0.82041534 when d=-20, 0.78161097 when d=-13.3333, 0.71846705 when d=-6.6667, 0.6318809 when d=0, 0.52839634 when d=6.6667, and 0.43914519 when d=13.3333. From these values, it can be seen that the radiation efficiency when d=-20, i.e., when the conductive member 10c is provided on the opposite side of the feeder 11, is the highest among the simulated arrangements. On the other hand, it can be seen that the radiation efficiency is inferior when L1=40 mm, W1=15 mm compared to when L1=60 mm, W1=30 mm, but even when L1=40, W1=15 mm, it can be seen that the radiation efficiency is sufficient to perform wireless power supply without any problems.

[0035] Fig. 6 is a graph showing the transition of the S-parameter according to the communication frequency of the antenna 1 with L1 = 40 mm and W1 = 15 mm. According to Fig. 7, it can be said that there is almost no difference in the S-parameter in the 920 MHz band, and it can be understood that there is no variation due to the arrangement position of the conductive member 10c. More specifically, when d = -20, the S parameter is -0.023152867, when d = -13.3333, the S parameter is -0.025011792, when d = -6.6667, the S parameter is -0.025784824, when d = 0, the S parameter is -0.020420918, when d = 6.6667, the S parameter is -0.020870058, and when d = 13.3333, the S parameter is -0.021026152, and it can be seen that there is no difference between these values.

[0036] The S-parameter shown in the graph of Fig. 6 indicates the return loss for 50 Ω. Basically, the lower the S-parameter value in decibel value in the frequency band used, the lower the reflectance, and the more preferable it is. From the graph of Fig. 6, it can be seen that the antenna in this case is not very favorable in terms of return loss for 50 Ω in the 920 MHz band, regardless of the position of the conductive member 10c.

[0037] Fig. 7 is a graph showing the transition of each S parameter according to the communication frequency of the antenna shown in Fig. 1 with the size of W1 = 15 mm, L1 = 40 mm, when the distance from the power transmission side is 1 m. Also, Fig. 8 is a graph showing the transition of each S parameter in the vertical direction according to the communication frequency of the same antenna, when the distance from the power transmission side is 1 m.

[0038] In Fig. 7, (S11, S12, S21, S22) in the 920 MHz band are (-46.70311, -21.271524, -21.164399, -42.548009), respectively. Also, in Fig. 8, (S11, S12, S21, S22) in the 920 MHz band are (-67.655771, -58.391212, -64.442047, -87.938023), respectively. In either case, in the 920 MHz band, the S parameter (S11) of Antenna 1 shows a large negative decibel value under matched conditions, and S21 (transmission characteristics) is improved, indicating that power can be supplied without any problems at a distance of 1 m.

[0039] 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. In addition, the performance is shown for the following cases: d is the distance from the center position of first conductive plate 10a and second conductive plate 10b in the longitudinal direction of conductive member 10c, 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, where the direction toward feeder 11 is positive.

[0040] As shown in Fig. 9, even when W1 = 20 mm and L1 = 50 mm, when d = -25, that is, when the conductive member 10c is provided at the end opposite in the longitudinal direction to the end of the first conductive plate 10a and the second conductive plate 10b where the feeder 11 is provided, the radiation efficiency is highest in the 920 MHz band, and it can be understood that the closer the conductive member 10c is to the feeder 11, the lower the radiation efficiency becomes. More specifically, when d = -25, the radiation efficiency is 0.88334688, when d = -19.4444, the radiation efficiency is 0.87004885, when d = -13.8889, the radiation efficiency is 0.84695073, when d = -8.3333, the radiation efficiency is 0.81796392, and when d = -2.7778, the radiation efficiency is 0.87004885. The radiation efficiency is 0.78302769 when d=2.7778, 0.74525835 when d=8.3333, 0.7139987 when d=13.8889, 0.70413104 when d=19.4444, and 0.71853238 when d=19.4444. That is, even when W1=20 mm and L1=50 mm, it can be understood that the radiation efficiency of the antenna 1 improves as the conductive member 10c is placed farther away from the feeder 11. Also, even when W1=20 mm and L1=50 mm, no matter where the conductive member 10c is placed, the radiation efficiency is 0.7 or more in the 920 MHz band, so it can be said that sufficient performance is exhibited in wireless power supply.

[0041] 2 to 9, as shown in FIG. 10, it can be said that the radiation efficiency of the antenna with W1=30 mm and L1=60 mm is higher than that of the antenna with W1=20 mm and L1=50 mm and that of the antenna with W1=15 mm and L1=40 mm. On the other hand, in the process of widening the antenna area, the radiation efficiency of the antenna tends to level off around W1=15 mm and L1=40 mm, and it can be said that there is not much difference in performance between them. In fact, even when W1=15 mm and L1=40 mm, it exhibits sufficient performance as a receiving antenna in wireless power supply. On the other hand, when it is assumed that the target to be equipped with the antenna is a relatively small IoT device, it can be said that a small size of the antenna is desirable for the IoT device, so it can be said that it is preferable to make the size of the antenna 1 as small as 15×40 mm. However, regardless of the size, it can be said that the antenna 1 according to the present invention exhibits a certain level of performance as a receiving antenna in wireless power supply.

[0042] Fig. 11 is a diagram showing an example of an antenna configuration different from that shown in Fig. 1. The antenna 1A shown in Fig. 11 shows an example in which the conductive member 10c in the antenna 1 is configured as a single conductive plate. That is, the 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 connected at the other end by the 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 by an individual plate and configured to be connected to each other so that electricity can be conducted, or the conductive plates 10a to 10c may be configured by bending a single conductive plate.

[0043] The upper graph in Fig. 12 shows the change in radiation efficiency according to the communication frequency when the antenna height is changed, and the lower graph in Fig. 12 shows the change in radiation efficiency according to the communication frequency when the antenna width is changed. The upper diagram of FIG. 12 shows the transition of the radiation efficiency of the 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 changed. As shown in the upper diagram of FIG. 12, it can be seen that the radiation efficiency of the antenna 1A increases as the height H2 is increased. However, as shown in the upper diagram of FIG. 12, it can be seen that the radiation efficiency becomes flat when the height H2 exceeds 5 mm, and that a large improvement in the radiation efficiency cannot be expected at around 10 mm. Considering that the antenna 1A is also mounted on a small device, it can be said that it is desirable for the size of the antenna 1A to be small if possible. Therefore, considering both the size and the radiation efficiency, it can be said that the height H2 should be about 5 to 10 mm. The same can be said about the height H1 of the antenna 1 in FIG. 1.

[0044] The lower diagram of FIG. 12 shows the transition of the radiation efficiency of the 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 changed. As shown in the lower diagram of FIG. 12, it can be seen that the radiation efficiency of the antenna 1A increases as the width W2 is increased. However, it can be seen from the lower diagram of FIG. 12 that the improvement rate of the radiation efficiency of the width also decreases from a certain length, as with the height. Specifically, the radiation efficiency becomes flat once the length of the width W2 exceeds 10 mm. Therefore, considering both the size and the radiation efficiency, it can be said that the width W2 should be about 10 to 30 mm, but it may be limited by the size of the device in which the antenna 1A is to be mounted.

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

[0046] The antenna pattern shown in FIG. 13 shows an antenna pattern with the antenna 1 at the center when the antenna 1A is viewed from the front (front view with the feeder 11 on the right, the conductive member 10c on the left, the first conductive plate 10a on the top, and the second conductive plate 10b on the bottom). That is, it is an antenna pattern when Theta=90° and Phi=0°, and shows an antenna pattern in the YZ plane. Since the antenna 1A is used as a power receiving antenna in wireless power supply, and since it is not possible to predict where a device such as a sensor equipped with the antenna 1A will be placed, it is desirable that the directivity of the antenna 1A is as uniform as possible. FIG. 13 shows the antenna pattern (directivity) when the areas of the first conductive plate 10a and the second conductive plate 10b of the 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 Fig. 13, when the height H2 is 2mm, it can be said that there is a large indentation in the antenna pattern at 0 degrees and 180 degrees. As the height H2 is increased, the indentation becomes smaller, and when H2 = 10mm, the indentation is small and the antenna pattern becomes closer to a circle (close to omnidirectional), so it can be understood that among these heights, H2 = 10mm is preferable for a power receiving antenna. H2 is not necessarily the higher the better, and it also depends on the payload of the device in which the antenna 1A is mounted, and it is preferable to set H2 to a height that does not distort the antenna pattern when it is increased.

[0048] From the above contents shown in Fig. 2 to Fig. 13, in the antenna 1 in which the long plate-like first conductive plate 10a and the second conductive plate 10b shown in Fig. 1 face each other and are connected at one end by the feeder 11 and further connected by the conductive member 10c, it can be said that the distance between the first conductive plate 10a and the second conductive plate 10b, i.e., the height of the antenna 1, is preferably about 10 mm, and the conductive member 10c is preferably connected to the first conductive plate 10a and the second conductive plate 10b at a position as far away as possible from the feeder 11, i.e., at the other end opposite to the end where the feeder 11 is arranged. In addition, it can be said that the size of the first conductive plate 10a and the second conductive plate 10b is preferably in the range of 15 mm x 40 mm among the various sizes mentioned above, but any size antenna can function sufficiently as a power receiving antenna as long as the antenna length is close to 1 / 4 λ of 920 MHz in the shape shown in Fig. 1 and Fig. 11.

[0049] 14(a)-(f) show various variations of the antenna according to the present invention, and show examples of various antenna configurations. Although not indicated by symbols in FIG. 14(a)-(f), the following description will be given with the understanding that the base is configured such that the first conductive plate 10a, the second conductive plate 10b, and the conductive plate 10c are arranged in a U-shape as shown in FIG. 11, and the ends of the first conductive plate 10a and the conductive plate 10c are connected by a feeder 11.

[0050] The antenna 1a shown in Figure 14(a) is the same as the antenna 1A shown in Figure 11. It is shown in Figure 14 for comparison with other embodiments.

[0051] The antenna 1b shown in Fig. 14(b) is a modified example of the antenna 1a. The antenna 1b shown in Fig. 14(b) has a shape in which a convex portion protruding toward the second conductive plate 10b is provided at the center of the first conductive plate 10a of the antenna 1a, and a convex portion protruding toward the first conductive plate 10a is provided at the center of the second conductive plate 10b. That is, the antenna 1b includes the first conductive plate 10a, the second conductive plate 10b facing the first conductive plate 10a, the conductive plate 10c, and the feeder 11, and 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.

[0052] Antenna 1c shown in Fig. 14(c) is another modified example of antenna 1a. As shown in Fig. 14(c), the antenna 1c has a shape in which the outer edge portions of conductive plates 10a-10c of antenna 1a remain. In other words, antenna 1c has a configuration in which conductive plates 10a-10c are formed from a single conductive plate, and the conductive plate is cut out from the end of each side by a predetermined distance on the inside, and then bent as shown in Fig. 14(c), and the end portions are connected by feeders 11. The conductive plate 10c 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 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.

[0053] 14(d) shows an antenna 1d in which the inside of the conductive plate 10c in the antenna 1a is cut out to form a frame shape. That is, the antenna 1d includes 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, where 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] 14(e) shows an antenna 1e which is different from antenna 1d in that slots are further provided in first conductive plate 10a and second conductive plate 10b. That is, antenna 1e is configured such that first conductive plate 10a having a slot extending in the longitudinal direction and second conductive plate 10b having a slot extending in the longitudinal direction are opposed to each other, connected at one end by feeder 11, and connected at the other end by plate-shaped conductive member 10c.

[0055] 14(f) is different from antenna 1e in that it further has protrusions 10d from both ends in the W2 direction of first conductive plate 10a toward second conductive plate 10b near the center in the longitudinal direction of first conductive plate 10a. That is, antenna 1f is configured such that second conductive plate 10b having a slot extending in the longitudinal direction and first conductive plate 10a having a slot extending in the longitudinal direction and having protrusions 10d extending vertically at the ends in the width direction near the center in the longitudinal direction face each other, are connected at one end by feeder 11, and are connected at the other end by plate-shaped conductive member 10c.

[0056] FIG. 15 shows the antenna 1f shown in FIG. 14(f) and a partially enlarged view thereof. As shown in the partially enlarged view of FIG. 15, the protruding portion 10d, which is an end portion in the width (W) direction of the first conductive plate 10a 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 is not connected to the second conductive plate 10b. That is, a predetermined gap is provided between the second conductive plate 10b and the protruding portion 10d. The performance of the antenna 1f also varies depending on the length of this gap. This point will be described later with reference to FIG. 19.

[0057] Below, we will consider the desirable shape of antenna 1 by comparing the performance of each antenna shown in FIG.

[0058] Fig. 16 is a graph showing the transition of the radiation efficiency according to the communication frequency of each antenna shown in Fig. 14. As shown in Fig. 16, in the 920 MHz band, the radiation efficiency is higher in the order of antenna 1f, antenna 1a, antenna 1d, antenna 1b, antenna 1e, and antenna 1c. More specifically, it was obtained by simulation that the radiation efficiency of antenna 1f in the 920 MHz band is 0.99010068, the radiation efficiency of antenna 1a in the 920 MHz band is 0.93002356, the radiation efficiency of antenna 1d in the 920 MHz band is 0.90709889, the radiation efficiency of antenna 1b in the 920 MHz band is 0.90532426, the radiation efficiency of antenna 1e in the 920 MHz band is 0.90475959, and the radiation efficiency of antenna 1c in the 920 MHz band is 0.79928906. For this reason, in terms of radiation efficiency, the most suitable antenna for the 920 MHz band is the shape of antenna 1f. However, regardless of the shape, it has a radiation efficiency of 0.7 or more and can therefore be said to meet the requirements as a receiving antenna.

[0059] FIG. 17 is a diagram showing antenna patterns (directivities) of the antennas shown in FIG. The antenna pattern on the right side of Fig. 17 shows the antenna pattern measured when each antenna shown in Fig. 14 is viewed from the top surface (first conductive plate 10a side) with feeder 11 positioned at the top end. That is, it shows the antenna pattern on the XY plane when θ = 90°. Simulations have revealed that the antenna pattern viewed from the top surface draws a circle that is nearly a perfect circle for each of the antennas shown in Fig. 14. Therefore, it can be said that there is no significant difference between the antennas in terms of the antenna pattern viewed from the top surface.

[0060] On the other hand, the antenna pattern on the left side of FIG. 17 shows the antenna pattern of each antenna shown in FIG. 14 when viewed from the conductive member 10c side. That is, it shows the antenna pattern on the XZ plane when Φ=90°. In the antenna patterns shown in FIG. 17, all the antenna patterns are elliptical with a major axis radius in the 90° direction and a minor axis radius in the 0° and 180° directions. The minor axis radius of the antenna pattern of antenna 1f is the longest, and the antenna pattern drawn by antenna 1f is closest to a circle. As shown in the figure, the minor axis radius of the antenna pattern is shortest in the order of antenna 1e, antenna 1c, antenna 1a, and antenna 1b, next to antenna 1f. As described above, the antenna shown in FIG. 14 is assumed to be used as a power receiving antenna in wireless power supply, and as an example, it is assumed to be mounted on a small sensor or the like as an IoT device. In this case, since it is not known where the IoT device will be installed, it is preferable for the antenna pattern to be one that can receive and be powered from radio waves from any direction. Therefore, of the antennas shown as antennas 1a to 1f, antenna 1f has the most preferable antenna pattern.

[0061] 16 and 17, it is inferred that the shape of antenna 1f is most suitable as a power receiving antenna for wireless power supply among the group of antennas shown in Fig. 14. The reason why antenna 1f showed high suitability will be explained with reference to Fig. 18.

[0062] Fig. 18 is a diagram showing that the antenna shown in Fig. 14(f) functions as a composite antenna. From Figs. 16 and 17, it seems that antenna 1f is efficient as a power receiving antenna, because it is presumed that antenna 1f functions as a composite antenna as shown in Fig. 18.

[0063] As shown in Fig. 18, it is estimated that the antenna 1f functions as two loop antennas, two slot antennas, and three dipole antennas. That is, the antenna 1f can be regarded as a composite antenna having six parts that function as antennas: a loop antenna 18g formed around the frame of the conductive member 10c, a loop antenna 18f formed by the end of the first conductive plate 10a-conductive member 10c-second conductive plate 10b-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 formed from the feeder 11-the center of the first conductive plate 10a-the protruding part 10d, and a dipole antenna 18b formed from the first conductive plate 10a-feeder 11, and as a result, it has been possible to show excellent antenna performance.

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

[0065] FIG. 19 shows the radiation efficiency when the distance (gap) between the protruding portion 10d and the second conductive plate 10b is changed in the range of 0 to 2.48 mm. As shown in FIG. 19, the radiation efficiency differs between when there is no gap (when the gap is 0 mm) and other cases, and it can be seen that the radiation efficiency is significantly lower in the configuration without a gap than in the configuration with a gap. More specifically, when the gap is other than 0 mm, the radiation efficiency is approximately 90% for any gap. This shows that in the antenna 1f, it is better to provide a gap between the protruding portion from the first conductive plate 10a and the second conductive plate 10b.

[0066] FIG. 20 is a diagram showing the antenna pattern (directivity) of the antenna when the gap between the protruding portion of the antenna shown in FIG. 14(f) and the second conductive plate is changed. FIG. 20 shows examples of antenna patterns when the gap is set to 0.02 mm, 0.13 mm, 0.2 mm, and 0.6 mm. The left side of FIG. 20 shows the antenna pattern when the antenna 1f is viewed from the top surface side and the longitudinal direction of the antenna 1f is the left-right direction of the drawing, and the right side of FIG. 20 shows the antenna pattern when the antenna 1f is viewed from the end, that is, from the feeder 11. That is, the left side of FIG. 20 shows the antenna pattern on the YZ plane when Φ=0°. The right side of FIG. 20 shows the antenna pattern on the XZ plane when Φ=90°.

[0067] As shown in Fig. 20, it was found by simulation that the antenna pattern formed is closest to a circle when the gap is 0.13 mm, followed by the antenna pattern that becomes smaller and closer to an ellipse when the gap is 0.02 mm, 0.6 mm, and 0.2 mm in that order. As described above, the antenna according to this embodiment is used as a power receiving antenna in wireless power supply, and since it is not known at the manufacturing stage where it will be installed, it is desirable to form an antenna pattern that is as wide-ranging and omnidirectional as possible.

[0068] Then, as shown in FIG. 20, considering that (i) the antenna pattern is closest to a perfect circle, (ii) the radiation efficiency is not significantly worse when the gap is narrower than when the gap is 2.48 mm, which provides the best radiation efficiency, and (iii) the antenna pattern when the gap is 0.6 mm, which provides the best radiation efficiency, is significantly worse than the antenna patterns when the gap is narrower, such as 0.13 mm or 0.02 mm (the antenna pattern is elliptical), it can be said from FIGS. 19 and 20 that, in the case of antenna 1f, it is better to provide a gap between the protrusion and second conductive plate 10b, and that the distance of the gap should be as short as possible so that the antenna pattern formed by antenna 1f is close to omnidirectional.

[0069] FIG. 21 is a diagram showing a configuration example in which an antenna is configured in a spherical shape. More specifically, the antenna shown in FIG. 21 shows an example in which the antenna 1f shown in FIG. 14(f) is configured in a curved shape (spherical in the drawing). As shown in FIG. 21, the antenna 1g is formed by connecting one end of a first conductive plate 10a having a slot and a second conductive plate 10b having a slot by a frame-shaped conductive member 10c with a cutout inside, and connecting the other end by a feeder 11. As shown in the drawing, the first conductive plate 10a, the second conductive plate 10b, and the conductive member 10c are curved in a spherical shape as a whole. In addition, a plate-shaped protruding portion protruding from the middle of the first conductive plate 10a toward the second conductive plate 10b is provided, and this protruding portion does not contact the second conductive plate 10b as shown in the drawing.

[0070] FIG. 22 is a graph showing the radiation efficiency of the antenna shown in FIG. 21 depending on the communication frequency.

[0071] As shown in FIG. 22, the antenna 1g having the shape shown in FIG. 21 exhibits a high radiation efficiency of 0.95751033 in the 920 MHz band, and it is understood that this antenna exhibits sufficient performance as a power receiving antenna.

[0072] FIG. 23 is a diagram showing the antenna pattern (directivity) of the antenna shown in FIG. 21. The left diagram of FIG. 23 is a diagram showing the antenna pattern when the antenna 1g is viewed from the top surface direction, that is, from the direction of the arrow 21A shown in FIG. 21, the center diagram of FIG. 23 is a diagram showing the antenna pattern when the antenna 1g is viewed from the side direction, that is, from the direction of the arrow 21B shown in FIG. 21, and the right diagram of FIG. 23 is a diagram showing the antenna pattern when the antenna 1g is viewed from the front direction, that is, from the direction of the arrow 21C shown in FIG. 21. In other words, the left diagram of FIG. 23 shows the antenna pattern on the XY plane when Φ=0°, the center diagram of FIG. 23 shows the antenna pattern on the XZ plane when θ=90°, and the right diagram of FIG. 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 somewhat elliptical in the left and right figures of Figure 23, but is nearly a perfect circle, and it can be seen that the shape in the center figure is almost equal to a perfect circle, and it can be seen that the antenna pattern has an almost ideal shape for an omnidirectional antenna.

[0074] Therefore, it was found that the antenna 1g, which is formed by bending the antenna 1f as shown in FIG. 21, can also be used as a power receiving antenna.

[0075] Fig. 24 is a diagram showing a configuration example in which an antenna is configured in a columnar (ring-shaped). More specifically, the antenna shown in Fig. 21 shows an example in which the antenna 1f shown in Fig. 14(f) is configured in a columnar shape. As shown in Fig. 24, the antenna 1h shows an example in which the antenna 1f is configured in a columnar shape by bending it in the longitudinal direction, and a first conductive plate 10a in the form of a long plate having a slot and curved in the longitudinal direction, and a second conductive plate 10b in the form of a long plate having a slot and curved in the longitudinal direction are connected at one end by a conductive member 10c curved in a frame shape with the inside cut out, and are connected at the other end by a feeder 11.

[0076] Fig. 25 is a graph showing the radiation efficiency according to the communication frequency of the antenna 1h shown in Fig. 24. As shown in Fig. 25, the antenna 1h having the shape shown in Fig. 24 exhibits a high radiation efficiency of 0.95761551 in the 920 MHz band, and it can be seen that the antenna 1h exhibits sufficiently high performance as a power receiving antenna.

[0077] Fig. 26 is a diagram showing the antenna pattern (directivity) of the antenna 1h shown in Fig. 24. The left diagram of Fig. 26 shows the antenna pattern when the antenna 1h is viewed from the direction of the arrow 24A, the center diagram of Fig. 26 shows the antenna pattern when the antenna 1h is viewed from the direction of the arrow 24B, and the right diagram of Fig. 26 shows the antenna pattern when the antenna 1h is viewed from the direction of the arrow 24C. In other words, the left diagram of Fig. 26 shows the antenna pattern on the YZ plane when Φ=90°, the center diagram of Fig. 26 shows the antenna pattern on the XY plane when Φ=0°, and the right diagram of Fig. 26 shows the antenna pattern on the XZ plane when θ=0°. As shown in FIG. 26, although the antenna pattern when viewed from the direction of arrows 24A and 24B is elliptical, the distortion is not significant, and the antenna pattern when viewed from the direction of arrow 24C can be said to be almost circular, so that 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 Fig. 21 to Fig. 26, when the antenna 1f is configured in a spherical or columnar shape, it can be understood that the antenna 1f has a certain degree of suitability as a power receiving antenna in wireless power supply, even when compared with the case where the antenna 1f is configured in a box shape as shown in Fig. 14(f). As an example of an antenna 1f having such a shape, it can be connected to a human sensor and installed in a columnar pen holder, for example, in a natural manner, so that an IoT device equipped with the antenna 1f can be installed in a manner that does not make people aware of it. This IoT device may operate and perform sensing using the power received by the antenna 1F, and transmit data obtained by sensing.

[0079] Fig. 27 is a diagram showing an example of the configuration of an antenna when a power receiving circuit is provided on one of the conductive plates. In the example shown in Fig. 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. Note that Fig. 27 shows an example in which the second conductive plate 10b is narrowed and extended in the direction of the first conductive plate 10a, but a conductive member connected to the second conductive plate 10b may be connected to the power receiving circuit via the feeder 11.

[0080] By configuring as shown in Fig. 27, the antenna 1 can be easily configured and the rigidity of the antenna 1 can be improved compared to the cases shown in Fig. 1, Fig. 11, etc. The performance of the antenna shown in Fig. 27 will be explained using Figs. 28 and 29.

[0081] Fig. 28 is a graph showing the radiation efficiency of the antenna shown in Fig. 27 according to the communication frequency. As shown in Fig. 28, the radiation efficiency of the antenna shown in Fig. 28 shows the radiation efficiency of the antenna according to the thickness of the first conductive plate 10a and a PCB (Printed Circuit Board) including a power receiving circuit, a power storage circuit, a sensor, a power storage device, and a microcontroller. Specifically, a simulation was performed in three cases: a case where the combined thickness of the first conductive plate 10a and the PCB is 0.3 mm, a case where the combined thickness of the first conductive plate 10a and the PCB is 1 mm, and a case where the first conductive plate 10a and the PCB are bonded together to a combined thickness of 0.3 mm, and the graph showing the radiation efficiency shown in Fig. 28 was obtained. According to this graph, it can be seen that the radiation efficiency of each antenna in the 920 MHz band was highest in the following order: 0.79228273 for the antenna when first conductive plate 10a and PCB were bonded together to a thickness of 0.3 mm, 0.62782387 for the antenna when first conductive plate 10a and PCB were bonded together to a thickness of 1 mm, and 0.59796367 for the antenna when first conductive plate 10a and PCB were not bonded together to a thickness of 0.3 mm.

[0082] From the radiation efficiency shown in FIG. 28, it is presumed that it is better to bond first conductive plate 10a of the antenna to the PCB and that the thickness is thinner. Fig. 29 is a diagram showing the antenna pattern (directivity) of the antenna shown in Fig. 27. The antenna pattern shown in Fig. 29 shows the antenna pattern when the antenna shown in Fig. 27 is viewed from the top surface, and as shown in the figure, in both cases, it has an elliptical shape, and it can be said that there is no significant difference. Therefore, taking FIG. 28 and FIG. 29 together, it is inferred that it is better to bond first conductive plate 10a of the antenna to the PCB and that the thickness is thinner.

[0083] Although not shown, as described above, the antenna 1 (1A, 1a to 1h) according to this embodiment may be configured as a power receiving antenna in wireless power supply, and may be configured as an IoT device that includes a capacitor or the like to receive and store power transmitted from a transmitter and supply it as power to operate a sensor or the like. The power received by the antenna 1 may be directly supplied to a sensor or the like, and sensing data obtained by sensing may be transmitted to an external server device or the like from a separate communication circuit using the power received by the antenna 1. In this case, the antenna 1 may be shared as a communication antenna for transmitting and receiving data if communication is possible as necessary.

[0084] Fig. 30 is a schematic diagram showing an example in which the antenna 1 according to this embodiment is cased to form an IoT device. Fig. 30(a) is an external view of the IoT device, and Fig. 30(b) is a perspective view of the inside of the IoT device. Fig. 31 is an exploded perspective view of the IoT device shown in Fig. 30(a).

[0085] As shown in Fig. 30(a), for example, the IoT device may be provided as a box-shaped housing 3000. As shown in Fig. 30(b), an example is shown in which an antenna 1f as an example of an antenna according to this embodiment and a PCB 3001 provided on the antenna 1f and connected to the antenna 1f are built in the housing 3000. Note that the housing 3000 is not limited to a box shape as long as it has an antenna 1 and a PCB 3001 built in therein, and may be, for example, a columnar shape, a cone shape, or a spherical shape.

[0086] FIG. 31 is an exploded perspective view of the housing 3000. As shown in FIG. 31, a PCB 3001 is provided on and connected to the antenna 1f. Although not shown, the PCB 3001 is equipped with various circuits for implementing functions to be implemented as an IoT device, such as a sensor corresponding to sensing executed as an IoT device, a power receiving circuit, a power storage circuit, a power storage device, and a microcontroller. The antenna 1f equipped with the PCB 3001 is sandwiched and built in between an upper housing 3100 and a lower housing 3101 to form an IoT device. In this way, the antenna 1 according to this embodiment may be provided as a part of the IoT device.

[0087] When providing it as an IoT device, an antenna 1 with the most appropriate size and high power receiving performance according to the size of the IoT device is selected and installed, and an IoT device that can continue to operate as long as it can receive power from a power transmitter while realizing the desired functions can be provided. In the case of this IoT device, since it is not necessary to install a large battery required for operating the IoT device, the size can be made relatively small and the cost increase associated with installing a large battery can be suppressed. Note that, although FIG. 31 shows an aspect in which a slot is also provided in the PCB in accordance with the antenna 1f, the PCB does not have to have a slot.

[0088] The antenna 1 may have a variable structure. For example, the antenna length may be changed by changing the length of the conductive member 10c and the feeder 11 using an elastic member (for example, a member that can be expanded or contracted by a sliding mechanism or the like).

[0089] The receiving antenna according to the present invention can efficiently receive power transmitted from a power transmitter at a distance of a certain distance or more (for example, 1 m, but not limited to 1 m, and may be 1 m or more). The receiving antenna according to the present invention can have a smaller planar area than a planar loop antenna often used for general wireless power supply, and can be provided as a receiving antenna that is easy to use in IoT devices equipped with a sensor device. The antenna according to the present embodiment can obtain a certain radiation efficiency or more even if it is changed to various sizes, so that when it is built into devices of various sizes and used, it can be provided as an antenna having a certain power receiving performance or more while having dimensions according to the devices. The antenna according to the present embodiment is an antenna having a radiation pattern with a directivity of approximately 0 dBi in all directions, and a device equipped with the antenna can receive power and operate wherever it is placed within a certain distance from a power transmitter that transmits power, as long as there is no object between the device and the receiving antenna that interferes with wireless power transmission.

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

[0091] In Fig. 11, the ends of the first conductive plate 10a and the second conductive plate 10b opposite to the ends connected by the conductive plate 10c are connected via a feeder 11. In a normal inverted-F antenna, the short-circuit part and the power supply part are located at a predetermined distance. In the antenna 1A, the ends of the first conductive plate 10a and the second conductive plate 10b opposite to the ends connected by the conductive plate 10c are connected via a feeder 11, and good simulation results are obtained for the radiation efficiency, reflectance, and directivity.

[0092] The length L2 of the antenna 1A is, for example, 40 mm to 60 mm as shown in Fig. 10. This length is, for example, approximately equal to 1 / 4 of the wavelength λ of radio waves in the 920 MHz band that are expected to be received by the antenna 1A. In this description, approximately equal 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. With the length L2 of 40 mm to 60 mm, the antenna 1A can efficiently receive radio waves in the 920 MHz band.

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

[0094] When a coaxial cable with a predetermined characteristic impedance is attached to the power supply of a normal inverted F antenna, 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 parts of the characteristic impedance are combined, and the imaginary parts are cancelled by the complex conjugate, so that it is possible to perform impedance matching efficiently. In addition, since the insertion loss generally increases when the inductance and capacitance values ​​increase, matching with reduced loss is possible by reducing the number of components and reducing the values. In particular, it is ideal that the value of R of 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 of the characteristic impedance R-jX (complex conjugate) of the feeder 11 (such as a rectifier circuit). Therefore, in order to achieve this, it is necessary to determine the length of the substrate that has a common R value at a low or high frequency, avoiding the vicinity of the antenna resonance (λ / 4).

[0095] The antenna 1A has the second conductive plate 10b as a ground, which makes it possible to prevent the antenna characteristics from being affected by the material of the surface of the member to which it is attached. This makes it possible to mount the antenna 1A on a metal surface or the surface of a conductive device or sensor, greatly improving usability.

[0096] Next, the Z parameter, that is, the impedance, of the antenna 1 shown in FIG. 1 will be described. Fig. 42 is a diagram showing the change in Z parameter, i.e., impedance, at various frequencies of the antenna 1 shown in Fig. 1. Fig. 42 shows simulation results for each frequency of the real part and the imaginary part. In Fig. 42, the upper graph shows the Z parameter corresponding to the real part's communication frequency, and the lower graph shows the Z parameter corresponding to the imaginary part's communication frequency. The component of the imaginary part is also called reactance.

[0097] According to FIG. 42, the values ​​of impedance and reactance in the 920 MHz band when the position of the conductive member 10c is changed are as follows: when d=-30, (real part, imaginary part)=(6513.8669 Ω, -2519.7886 Ω); when d=-23.3333, (real part, imaginary part)=(6096.2638 Ω, -2551.2409 Ω); when d=-16.6667, (real part, imaginary part)=(5876.8777 Ω, -2089.0102 Ω); when d=-10, (real part, imaginary part)=(5154.6372 Ω, -1921.7748 Ω); and when d=-3.3333, (real part, imaginary part)=(54.6372 Ω, -2089.0102 Ω). , (real part, imaginary part) = (4282.2143Ω, -1713.465Ω), when d = 3.3333, (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 of FIG. 42, the impedance increases sharply around the 920 MHz band, regardless of the position where the conductive member 10c is placed. From this, it can be understood that the antenna 1 is an antenna that resonates with the 920 MHz band. Also, the higher the dB, the higher the degree of resonance. According to FIG. 42, when d=-30, the impedance is the highest in the 920 MHz band. Therefore, when the conductive member 10c is placed at the position of d=-30, that is, the position farthest from the feeder 11, the radiation efficiency is the highest.

[0099] If we assume that R+jX is the antenna impedance, there are two points where the real part is R (Figure 44). As explained above, the ideal antenna impedance is when it is the complex conjugate of the rectifier circuit. The ideal matching condition is when the antenna impedance is R+jX and the rectifier circuit impedance is R-jX, but it is difficult to actually achieve this matching. Generally, the real part of the rectifier circuit is 50 ohms or less, and is often around a few tens of ohms. Therefore, near the antenna resonance, the R value is extremely high, at several thousand ohms, but it is better to adjust this to a few tens of ohms.

[0100] As for matching the real impedance of the antenna and the real impedance of the rectifier, as described in Fig. 44, in the low frequency band, the R value can be lowered by shortening the antenna length L by 10 to 30%, preferably by about 20%, and matching can be performed to the desired R value. In addition, in the high frequency band, the R value can be lowered by lengthening the antenna length L by 10 to 30%, preferably by about 20%, and matching can be performed to the desired R value. By performing impedance matching in the low frequency band, it is possible to shorten the antenna length L by about 10 to 30% from the initial state, and it is also possible to miniaturize the entire antenna. If the result falls below the specified target value, i.e., the R value is too low and you want to increase it, it is possible to adjust the R value by lengthening the antenna length L in low frequency bands and shortening the antenna length L in high frequency bands. The ideal length of an antenna is 1 / 4 wavelength, but by adjusting the antenna length by about ±20% from this, it is possible to approach ideal matching.

[0101] If the respective impedance R values ​​can be made uniform, then only the jX value needs to be adjusted, making it possible to achieve impedance matching with a single component.As an example, at 920 MHz, impedance matching between the antenna and rectifier is achieved by inserting one 22 nH inductor in series in an antenna (with Teflon (registered trademark) base material) that is 60 mm long, 16 mm wide, and 8 mm high. If the initial state of the antenna is a length that has a resonant frequency equal to the frequency band of the radio waves that are expected to be received, that is, for example, a length that is 1 / 4 the receiving wavelength λ, then by performing impedance matching at a low frequency, it is possible to shorten the antenna length L from the initial state by about 10 to 30%, preferably about 20%, making it possible to miniaturize the entire antenna.

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

[0103] Example 2 In the first embodiment, various types of power receiving antennas 1, 1A, and 1a to 1h have been described with reference to FIGS. 1 to 31 and 42. FIG. Next, an antenna 20 according to a second embodiment will be described. In the following, in order to avoid duplication, the description of the parts that overlap with the antennas 1, 1A, and 1a to 1h according to the first embodiment will be omitted.

[0104] The antenna 20 according to the second embodiment can be used as a power receiving device in wireless power feeding, similarly to the first embodiment. That is, the antenna 20 according to the second embodiment can be used as a power receiving device that receives energy wirelessly transmitted in a three-dimensional space based on WPT (Wireless Power Transmission or Wireless Power Transfer). The antenna 20 according to the second embodiment can transmit the received energy to any target such as a sensor, a robot, a device, or a PC. The antenna 20 according to the second embodiment can be implemented as an antenna or a rectenna. The antenna 20 according to the second embodiment can be implemented as a module (such as an antenna module) in which an antenna or rectenna is integrated with related electronic components. The antenna 20 according to the second embodiment can be implemented as a module (such as a sensor module) that integrates an antenna or rectenna, related electronic components, and a sensor or the like to which power is to be transmitted.

[0105] First, a basic configuration of an antenna 20 according to the second embodiment will be described with reference to FIGS. FIG. 32 is a diagram showing an example of a basic configuration of an antenna according to the second embodiment and a core material applicable thereto. 32(A) shows a perspective view of the antenna 20 according to the second embodiment, as viewed from the same direction as the antenna 1A according to the first embodiment shown in FIG. 32(B) shows a perspective view of the antenna 20 seen from the opposite side. These figures allow the basic configuration of the antenna 20 according to the second embodiment to be understood from all angles. In the power receiving antennas 1, 1A, and 1a to 1h according to the first embodiment, the plate thickness is omitted and the structure is illustrated generally (see, for example, FIG. 11 and FIG. 14(a) to (f)). In FIG. 32(A) and (B), the plate thickness of the antenna 20 is illustrated more specifically.

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

[0107] The antenna 20 illustrated in Figure 32(A) is similar to Example 1 illustrated in Figure 11 in particular, in that a first conductive plate (conductive member) 21 and a 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 are connected to each other 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, a closed current path is created by the first conductive plate 21, the third conductive plate 23, the second conductive plate 22 and the feeder 25, forming a loop antenna 50, as illustrated by the arrows in Figures 32(A) and (B).

[0108] Strictly speaking, the loop antenna 50 is different from a general "loop antenna", but since a loop is formed by the three conductive plates and the feeder 25, this is called a "loop antenna" in this embodiment. This antenna functions as, for example, a power feeding antenna. Similarly, the loop antenna 18f formed by the first conductive plate 10a, the conductive member 10c, the second conductive plate 10b, and the end of the feeder 11 illustrated in FIG. 18 of the first embodiment is also called a "loop antenna" since a loop is formed, although strictly speaking, the principle is slightly different from that of a general loop antenna. Also, the direction of the arrow of the loop antenna 50 illustrated in FIGS. 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 at a predetermined interval and extend substantially parallel to each other in substantially the same direction. Note that 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 a long plate shape. The lengths and directions of the four sides of the long 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. In addition, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 may be entirely or partially flat, curved, or a combination thereof. In the illustrated embodiment, the third conductive plate 23 is connected to the first conductive plate 21 and the second conductive plate 22 so as to be substantially perpendicular to them. However, as will be described in detail below, particularly from the viewpoint of the efficiency of the loop antenna 50, the connection angle of the third conductive plate 23 is not limited to 90 degrees.

[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 so as to have a substantially U-shape (substantially U-shape or substantially C-shape) in cross section. In the bending process, for example, a die may be used to plastically process 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 by an individual conductive plate and electrically connected to each other.

[0111] In the second embodiment, a hollow space 24 with a predetermined size can be defined by punching at least one of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23. For example, a press punching process can be performed on the third conductive member 23 to define a substantially rectangular hollow space 24 at an arbitrary location. The size and shape of this hollow space can be determined so that the inverted-F type antenna 60 can be attached therein.

[0112] In the first embodiment, the antenna 1d illustrated in Fig. 14(d) and Fig. 18 is configured to have a loop antenna 18g formed from the periphery of a frame of a conductive plate 10c cut out from inside. In the second embodiment, the conductive plate 23 is similarly cut out from inside, but the main purpose of the punching process is not to form a loop antenna. Therefore, in the second embodiment, the size of the periphery frame defining the hollow space 24 (also called a cutout or notch), the thickness of the frame, etc. may differ from those in the first embodiment.

[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 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 have antenna patterns for two different frequencies. 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 an antenna for receiving power, and the inverted-F antenna 60 can be used as an antenna for data communication.

[0115] Specifically, the antenna 20 according to the second embodiment can configure a power transmission / reception antenna in the 920 MHz band using the loop antenna 50, and a data communication antenna in the 2.4 GHz band using the inverted-F antenna 60. However, the bands of the antennas are not limited to this example. For example, the loop antenna 50 may provide a power reception antenna in the 900 MHz band, and the inverted-F antenna 60 may provide a data communication antenna in the 5.6 GHz band.

[0116] The antenna 20 illustrated in Figures 32(A) and (B) allows the use of two different types of antennas 50 and 60, thereby expanding the range of applications and contributing to reducing the antenna design burden on the user. In particular, the antenna 20 is suitable for application to applications based on wireless power transmission. A wireless sensor network requires a power receiving antenna and a data communication antenna. For example, IoT sensing using wireless power supply may require simultaneous use of two bands, a 920 MHz band for wireless power supply and a 2.4 GHz band for data communication. The antennas illustrated in Figs. 32(A) and (B) can provide these two antennas and are therefore suitable for application in this field.

[0117] Furthermore, the antenna 20 according to the second embodiment can be manufactured compactly by integrating these two antennas, which allows the antenna, rectenna, and / or module to be miniaturized, making it possible to apply the antenna to a wide variety of fields. 32(A) and (B), the first conductive plate 21 and the second conductive plate 22 each have a predetermined width dimension W3 and a predetermined length dimension L3, and secure a predetermined area A3 in the two-dimensional direction. Using this area A3, it is possible to mount an electronic circuit or 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 substrate, and refers to a printed wiring board (PWB) with electronic components attached thereto 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 can include, but is not limited to, a power receiving circuit, a power storage circuit, a sensor, a power storage device, and a microcontroller.

[0119] The antenna 20 illustrated in Figures 32(A) and (B) can be configured as a dual-band antenna (or a multi-band antenna) and can be used anywhere. In particular, even if the conductive plate 22 is installed on a metal surface or a conductor, the antenna 20 can be configured as a loop antenna in which a current flows in a loop in the space between the conductive plates 21 and 22, and the reception efficiency does not decrease significantly. Therefore, the antenna 20 can be easily installed on a metal surface or the surface of a conductive device or sensor, greatly improving usability. The basic structure of the antenna 20 has been conceptually illustrated above with reference to FIGS.

[0120] 34A and 34B are diagrams illustrating an example of mounting an antenna according to the second embodiment. In particular, the electronic circuit layer 44 (see FIG. 33) disposed above the first conductive plate 21 is illustrated more specifically in FIGS. 34(A) and (B). The configurations illustrated in Figures 32(A) and 32(B) do not necessarily have to strictly correspond to the configurations illustrated in Figures 34(A) and 34(B). For example, depending on the three-dimensional shape of the electronic circuit, the coverlay 45 illustrated in Figure 33 can be partially omitted. Furthermore, the electronic circuit may be arranged not only on the upper surface of the first conductive plate 21, but also by utilizing a part of the third conductive plate 23 and / or the second conductive plate 22 (not shown). The coverlay 45 and the like will be described later.

[0121] The antenna 20 shown in Fig. 34(A) can be made relatively small by the wavelength shortening effect when a core material is inserted, and can be made to be, for example, small enough to fit in an adult's hand. The core material and other details will be described later. For example, the antenna 20 may have a longitudinal dimension L3 illustrated in FIG. 32(A) of approximately 40 mm to 60 mm. Moreover, the antenna 20 may have a plate thickness of each conductive plate of several mm, or of approximately 5 mm to 8 mm. However, each dimension of the antenna 20 is not limited to the numerical range exemplified above.

[0122] In FIGS. 34(A) and (B), the electronic circuits mounted on the antenna 20 may include, for example, a power source, a sensor driving circuit, and / or a wireless communication circuit. When configuring the antenna 20 as a dual-band antenna, it is conceivable that the power supply voltage is received from the loop antenna 50 (e.g., 920 MHz) and the data acquired by the sensor is transmitted by radio waves from the inverted-F antenna 60 (e.g., 2.4 GHz). In this case, the connection must be made by wire. In this way, when a PCB (electronic circuit) is provided on the antenna 20, an increase in the height dimension can be expected by the thickness of the PCB.

[0123] Therefore, instead of the PCB, a flexible printed circuit board (FPC: Flexible Printed Circuits) can be used when constructing the antenna 20. The FPC has flexibility and can be formed using, for example, a thin insulating material (plastic film). For example, the antenna 20 may be configured using a two-layer FPC, in which the first layer is a 920 MHz band antenna (loop antenna 50), and the second layer is configured as a rectifier circuit, a power supply, a sensor control circuit, a wireless communication circuit, and a 2.4 GHz band antenna (inverted-F antenna 60). Preferably, a PCB or FPC is optionally used to construct antenna 20 that is relatively small and has a low profile (reduced height).

[0124] Next, the internal shape of the antenna 20 will be described. In the first embodiment, as illustrated in Fig. 11 etc., the first conductive plate 10a, the second conductive plate 10b and the third conductive plate 10c are configured to have a substantially U-shape in cross section and are hollow inside, which is advantageous in terms of reducing the weight, number of parts, cost and effort required for processing the product. 32(A) and (B), the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 are configured to have a substantially U-shape in cross section, and the inside can be made hollow. In this case, there is an advantage in terms of suppressing the weight of the product and ensuring the performance of the loop antenna 50.

[0125] Here, when the inside shape of the antenna 20 is hollow, it is advisable to fix the distance between the two parallel conductive plates 21, 22 to maintain the shape of the product and ensure its strength. Therefore, in Example 2, a rigid core material 30 made of a dielectric is further inserted between the two parallel conductive plates 21, 22, thereby improving the shape and strength of the product and reducing the size of the loop antenna 50 by utilizing the wavelength shortening effect.

[0126] 32(C) and (D) show an example of a core material 30 that can be inserted into the antenna shape shown in FIG. 32(A) and (B). 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 FIG. 32(A) is formed as a substantially rectangular parallelepiped as a whole, and has a predetermined width dimension W3, length dimension L3, and height dimension H3. Similarly, the core material 30 shown in FIG. 32(C) has a body 31 formed generally in a rectangular parallelepiped shape, with a predetermined width dimension W4, longitudinal dimension L4, and height dimension H4.

[0127] The dimensions W4, L4, and H4 of the core material 30 can be arbitrarily determined so that the core material 30 can be filled inside the antenna 20. In general, when the dielectric constant (ε, epsilon) of the core material 30 is high, the dimensions (any of W3, L3, and H3) of the antenna 20 can be shortened due to the wavelength shortening effect, compared to when the core material 30 is not used, thereby enabling the antenna 20 to be miniaturized. This miniaturization effect is not limited to dual-band antennas, but is also applicable to antennas 20 configured as single-band antennas. It is not necessary for the main body 31 of the core material 30 to be provided over the entire area of ​​the internal shape of the antenna 20. If necessary, the core material 30 may be filled only in a part of the internal shape of the antenna 20.

[0128] Moreover, the body 31 of the core material 30 is not limited to being solid. If necessary, the body 31 can be perforated. If necessary, a hollow space may be provided inside the body 31. Providing a hollow space allows the overall body to be made lighter, and improves the power receiving efficiency, i.e., the radiation efficiency. Furthermore, efficiency can be improved by devising a hollow shape to make the space wider in the center and narrower at the tip of the antenna. Furthermore, the main body 31 of the core material 30 is not limited to being a single part, but may be composed of two or more parts as necessary.

[0129] The core material 30 is preferably a dielectric material. For example, the core material 30 can be made of plastic. Plastic is a type of dielectric material. Plastic is an organic polymeric material with plasticity, and is sometimes called synthetic resin. Plastic is an advantageous material for mass production because it is easy to process into complex shapes and is inexpensive.

[0130] More preferably, the core material 30 can be made of acrylic. Acrylic is a type of plastic, and refers to acrylic resin and acrylic fiber. It is also called acrylic glass. Acrylic is not only highly transparent and aesthetically pleasing, but is also a relatively hard material. Acrylic is considered to be relatively weak against impact, but by making the acrylic thicker, it is possible to increase the impact resistance.

[0131] Alternatively, the core material 30 can be made of polycarbonate, which is a type of plastic, and is particularly a material made from polycarbonate resin. Alternatively, the core material 30 may be made of polytetrafluoroethylene (PTFE; fluororesin). For example, the core material 30 may be made of Teflon (registered trademark). Alternatively, the core material is not limited to plastic, acrylic, polycarbonate, PTFE, etc., and other materials having a high dielectric constant may be used. In addition, since Teflon has a low dielectric loss, the use of Teflon improves radiation efficiency compared to other core materials.

[0132] Therefore, the strength of the antenna 20 can be improved by configuring the conductive plates 21, 22, and 23 to be wound around the core material 30. For example, the antenna 20 may be configured by winding the FPC around the core material 30. Since the FPC is flexible, it can be easily wound around the core material 30 that has a curved surface as well as a flat surface.

[0133] By forming the antenna 20 uniformly in the width direction, it is possible to improve production efficiency when manufacturing a large number of antennas 20, for example, as illustrated in Fig. 41. For example, multiple sets of antennas and circuit boards are molded in parallel on an FPC (see the three solid and dashed line reference symbols 20), the FPC on which these multiple sets of antennas and circuit boards are mounted is wound around a long core material, and then the FPC together with the core material is cut for each set of antennas and circuit board (see the single solid line reference symbol 20), thereby making it possible to efficiently manufacture a plurality of antennas 20.

[0134] The core material 30 may be processed separately from the antenna 20, which is a substantially rectangular parallelepiped consisting of the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23, and then inserted and bonded inside the antenna 20. For example, an epoxy resin adhesive or the like may be used as the adhesive. Alternatively, the core material 30 may be injection molded in any manner.

[0135] In this manner, by inserting the core material 30 between the two conductive plates 21, 22 spaced apart from each other, the shape of the product is maintained and strength of the product is 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 30. However, when the core material 30 is inserted inside the antenna 20, the power receiving efficiency of the loop antenna 50 may decrease due to the dielectric loss caused by the material.

[0136] Therefore, when using the core material 30 inside the antenna 20, it is preferable to use a material with as little dielectric loss as possible in order to avoid a decrease in the functions of the loop antenna 50 and the inverted F-shaped antenna 60. For example, the above-mentioned plastics, acrylic, polycarbonate, 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 preferable.

[0137] FIG. 33 is a diagram showing an example of a cross-sectional configuration of the side surface 26 of the first conductive plate 21 of FIG. 32(B). 33, the first conductive plate 21 has a multi-layer structure made up of a plurality of layers 41 to 45, and is, for example, a two-layer FPC. A two-layer FPC means that the circuit uses two layers of copper foil. The multi-layer structure of the first conductive plate 21 is not limited to the five layers shown as an example. A multi-layer structure with a smaller or larger number of layers is possible. The second conductive plate 22 and the third conductive plate 23 can also be multi-layered, but their configurations can be different from that of the first conductive plate 21.

[0138] For example, the bottom layer 41 of the first conductive plate 21 is a coverlay. A coverlay corresponds to a protective layer. The coverlay may be made of any material to provide electrical, mechanical, chemical and / or thermal protection to its surroundings. For example, the second-lowest layer 42 of the first conductive plate 21 is a conductive layer. This conductive layer is made of, for example, copper foil. The copper foil forms the first conductive plate 21 and is used to configure the 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 made of a material that has particularly excellent electrical insulation properties, and is 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 by this copper foil, or an electronic circuit, battery, sensor, etc., separately molded in this copper foil are electrically connected. Also, an inverted-F antenna 60 can be molded from the copper foil of layer 44 in a form connected to this electronic circuit. For example, the fifth layer 45 from the bottom of the first conductive plate 21 is a coverlay. The material of the layers 42 and 44 is not limited to copper, but may be other conductive materials.

[0140] Moreover, by using a multi-layered FPC rather than just the five-layered one shown in Fig. 33, it becomes possible to form a more complicated electronic circuit on the conductive plate 21. Also, by increasing the number of layers, a ground layer can be provided, and by separating the antenna ground from the circuit ground, it becomes possible to further suppress interference. In this way, the conductive plates 21, 23, 22, the inverted F antenna 60, and the circuit are integrally molded using an FPC, and then wrapped around a core material to form a dual antenna having the loop antenna 50 and the inverted F antenna 60, thereby making it possible to easily manufacture the antenna 20 of this embodiment.

[0141] Layer 44 of the electronic circuit arranged above first conductive plate 21 and layer 42 of loop antenna 50 arranged below it are insulated from each other by insulating layer 43 except for some contact points. Therefore, even if an electronic circuit is stacked above first conductive plate 21, it is designed not to impair the function of loop antenna 50 formed by the same first conductive plate 21. In addition, a loop antenna 50 is formed using the copper foil of layer 42 of the two-layer FPC, and an inverted-F antenna 60 is formed using the copper foil of layer 44. Since each is insulated by a polyimide layer 43 between them, each antenna can be driven independently and the performance of each antenna is maintained.

[0142] Although layer 43 provides insulation between layers 42 and 44, high frequency components may pass through. However, as described above, inverted-F antenna 60 is made of the second conductive layer of the FPC in the multi-layer structure, and is disposed in hollow space 24 formed by hollowing out a portion of layer 42. Therefore, since inverted-F antenna 60 is disposed in a location with low current density, interference between loop antenna 50 and inverted-F antenna 60 is suppressed.

[0143] Moreover, the loop antenna 50 is disposed inside the antenna 20 (see reference numeral 50 in FIG. 32(A)). That is, the antenna 20 has a substantially U-shape in cross section, and the electric field of the loop antenna 50 is generated inside the U-shape (substantially C-shape or substantially U-shape). FIG. 43 is an example of a diagram showing the results of a simulation of the electric field of the 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, when the antenna illustrated in FIGS. 32(A) and (B) is placed, for example, with the first conductive plate 21 on top and the second conductive plate 22 on the bottom, the function of the loop antenna 50 is not impaired regardless of the material of the installation surface. The same applies when the antenna is placed upside down.

[0144] To configure a completely wireless sensor module, it is advisable to configure not only the power supply but also the data communication section for transmitting sensor data wirelessly. If a PCB is installed on one side of the antenna to provide power, drive the sensor, and perform wireless communication, the antenna for wireless communication can be configured as a pattern antenna on the PCB. However, when a pattern antenna of an electronic circuit is formed on the first conductive plate 21, a correspondingly large area is required in the two-dimensional direction.

[0145] In contrast, in the antenna 20 according to the second embodiment, when the loop antenna 50 is configured along the side surfaces of the conductive plates 21, 22, and 23 extending in a substantially U-shape, an antenna for a data communication band (for example, an inverted-F antenna 60) is configured using a part of the area of ​​the conductive plates 21, 22, and 23, thereby realizing miniaturization of the entire antenna. As a result, a pattern antenna on the same plane as the circuit board is no longer necessary, and it is accordingly possible to make more extensive use of the upper surface of the first conductive plate 21.

[0146] As shown in the antenna mounting examples in Figures 34(A) and (B), various mounting methods are possible for an antenna 50 for wireless power supply in the 920 MHz band, for example, and an antenna 60 for data communication in the 2.4 GHz band, for example. For example, referring to Figure 34(B), a hollow space 24 is provided on the surface of a first conductive plate 21 of an antenna 20, and an inverted-F antenna 60 is disposed therein. 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 antenna 60 is disposed therein. 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 one FPC, it is possible to reduce the size of the antenna 20 and the number of assembly steps.

[0147] Next, a modification of the loop antenna 50 of the antenna 20 will be described. FIG. 35 is an example diagram showing a variation of the antenna and the core material that can be applied therein. The shape of the loop antenna 50 is based on the external shape of the conductive plates consisting of the first conductive plate 21, the second conductive plate 22, and the 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 substantially parallel to each other, and are connected at an angle of approximately 90 degrees at the end side by the third conductive plate 23. The performance of the loop antenna can 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 end sides by the third conductive plate 23 at an angle greater than 90 degrees and with more corners.

[0148] 35(A) and (B), the third conductive plate 23 is bent into a polygonal shape as illustrated by the reference numerals 26 and 27. At the opposite ends, the first conductive plate 21 and the second conductive plate 22 are similarly bent into a polygonal shape as illustrated by the reference numerals 28 and 29. Therefore, the antenna 20 as a whole has a body that is substantially octagonal in cross section. Therefore, the shape of the loop antenna 50 is changed from the approximate square shape shown in Figures 32(A) and (B) to the approximate octagon shape shown in Figures 35(A) and (B). By making the shape of the loop antenna 50 closer to a circle (or an ellipse), it is possible to expand the range of designs and to expect improvement in the performance of the antenna.

[0149] 34(A) and (B) again, the first conductive plate 21 and the second conductive plate 22 extend substantially parallel to each other, and are connected at their ends in a curved (or arc) shape by the third conductive plate 23. In this case, by making the external shape of the loop antenna 50 closer to a circle (or an ellipse), it is possible to expand the range of designs and to improve the performance of the antenna. In this case, the third conductive plate 23 may extend in a curved shape (arc shape) as a whole, or, as particularly illustrated in Figures 34(A) and (B), the third conductive plate 23 may extend in a partially curved shape at both ends and partially extend straight in the center.

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

[0151] When filling the inside of the antenna 20 with the core material 30, the shapes of the conductive plates 21, 22, and 23 may be modified so as to enhance the holding effect. 35(A) and (B), for example, the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23 have a generally octagonal shape as a whole. In this case, the third conductive plate 23 is bent in multiple stages (see reference numerals 26 and 27). Correspondingly, the first conductive plate 21 and the second conductive plate 22 each have their end portion folded back inward (see reference numerals 28 and 29).

[0152] It is also preferable that the external shape of the body 31 of the core material 30 housed inside the antenna 20 is matched to the internal shape of the antenna 20. For example, in the case of the example shown in Figures 35(C) and (D), the corners of the body 31 of the core material 30 may be chamfered (see Nos. 36, 37, 38, and 39). The holding force of the core material may be increased by forming the antenna 20 and the body 31 of the core material 30 into a polygonal shape in cross section. Furthermore, the first conductive plate 21, the second conductive plate 22 and the third conductive plate 23 may have convex or concave portions at any desired locations, and corresponding concave or convex portions may be provided in the main body 31 of the core material 30 to engage the core material at that location, thereby increasing the holding force of the core material.

[0153] Next, a modification of the inverted-F antenna 60 will be described. 36(A) to (D) show modified examples of the inverted-F antenna 60 shown in FIGS. 32(A) and (B). 36(A), the inverted-F antenna 60 is mainly composed of a power feeder 61, a short-circuiting line 62, and a main body 63. The power feeder 61, the short-circuiting line 62, and the main body 63 are each adjustable in thickness, length, position, shape, etc. according to the embodiment. For example, the thicknesses of the power supply line 61, the short-circuit line 62, and the main body portion 63 may be adjusted. For example, the length of the main body portion 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 antenna 60 can be adjusted according to the embodiment. For example, as shown in FIG. 36(A), an inverted-F antenna 60 can have a main body 63 configured in a simple line shape (monopole antenna shape). For example, as illustrated in Figure 36(B), the inverted-F antenna 60 can be configured so that, instead of configuring the main body 63 in a simple line shape, it is bent further inward at approximately 90 degrees from the state shown in Figure 36(A) (see symbol 64). For example, as shown in FIG. 36(C), the inverted-F antenna 60 can be configured such that the main body 63 is further folded inward at approximately 90 degrees from the state shown in FIG. 36(B) (see reference numeral 65).

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

[0156] Furthermore, the inverted-F antenna 60 can be installed anywhere on the antenna 20. Referring to Figures 34(A), (B), 36(A) to (C), etc., the inverted-F antenna 60 is disposed in a hollow space 24 provided on the side (third conductive plate 23) of the rectangular parallelepiped antenna shape. With reference to FIG. 36(D) and other figures, the inverted-F antenna 60 is disposed in a hollow space 24 provided on the upper surface (first conductive plate 21) of the rectangular parallelepiped antenna shape.

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

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

[0159] In this way, the inverted-F antenna 60 or the chip antenna can be attached anywhere, such as to the side or top surface of the antenna 20. However, preferably, an installation area for an electronic circuit (PCB or FPC) needs to be secured on the top surface of the antenna 20, as described above. For this reason, when attaching an inverted-F antenna to the top surface of the antenna 20, the size of the top surface may be made larger accordingly, compared to when the antenna is attached to the side surface. For example, referring to Fig. 36(C), almost the entire area (see area A3) of the top surface of a rectangular parallelepiped antenna having dimensions of length L3, width W3, and height H3 is reserved as the installation area for electronic circuits. In this case, the area of ​​A3 can be approximated as L3 x W3.

[0160] Also, referring to Fig. 36(D), when an inverted F-shaped antenna or a chip antenna is attached to the top surface of a rectangular parallelepiped antenna, the rectangular parallelepiped antenna is configured to be more elongated in order to secure the installation area of ​​the electronic circuit (see area A5). For example, the rectangular parallelepiped antenna has the 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 in particular is increased to L5. The value of width W3 may be increased to W5. Preferably, the value of A5 is approximately the same as the value of A3.

[0161] As described above, the antenna 20 according to the second embodiment preferably has a body of a substantially rectangular parallelepiped shape, and its cross section is substantially U-shaped. This substantially U-shaped shape may include any mode 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 mode includes a straight mode (see FIG. 32(A)) of the third conductive plate 23 connecting the first conductive plate 21 and the second conductive plate 22, a substantially polygonal mode (see FIG. 35(A)), and a substantially curved (arc-shaped) mode (see FIG. 34(A)).

[0162] However, the shape of the antenna 20 according to the second embodiment 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 according to the first embodiment illustrated in FIG. For example, the antenna 20 can be configured in a columnar shape similar to the antenna 1f according to the first embodiment illustrated in FIG. For example, the antenna 20 can be configured in any other shape, such as a polyhedron, a triangular prism, a polygonal prism, a circular cylinder, an elliptical cylinder, or the like.

[0163] As described above, the antenna 20 according to the second embodiment forms the loop antenna 50 by using the first conductive plate 21, the second conductive plate 22, and the third conductive plate 23. 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 according to the second embodiment is not limited to this shape. For example, the antenna 20 can be configured with slots provided in the first conductive plate 10a and / or the second conductive plate 10b, similar to the antenna 1e according to the first embodiment illustrated in FIG. 14(e). In this case, as illustrated in FIG. 18, it is also possible to provide 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 the second embodiment has been described above with reference to FIGS. The antenna 20 according to the second embodiment 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 used to configure a power receiving antenna of a first frequency (e.g., 920 MHz), and the inverted-F antenna 60 can be used to configure a data communication antenna of 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 chip antenna. Furthermore, the antenna 20 according to the second embodiment may 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 the second embodiment may be configured as a multi-band antenna to simultaneously realize 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, another loop antenna may be added to the loop antenna 50 and the inverted-F antenna 60. Alternatively, a linear antenna such as a monopole antenna or a dipole antenna may be added to the loop antenna 50 and the inverted-F antenna 60.

[0167] In this manner, the antenna 20 according to the second embodiment is capable of receiving one or more bands, and can be configured as an antenna, a rectenna, or a circuit module (for example, an antenna module or a sensor module, etc.). Next, with reference to Figs. 37 and 38, an implementation example in which the antenna 20 is used to feed power to a sensor and operate it will be described.

[0168] FIG. 37 is a diagram illustrating an implementation example in which the antenna according to the second embodiment is used to feed power to a sensor. A transmitter 70 having a transmission function is shown on the left surrounded by a dotted line, and a receiver 80 having a receiving function is shown on the right surrounded by a dotted line. The transmitter 70 and the receiver 80 are spaced apart from each other at a predetermined distance. For example, the transmitter 70 and the receiver 80 are spaced apart from each other at a distance of about 1 m. In this example, when the distance between the transmitter and the receiver is 1 m, charging of about 1 mW to 3 mW or about 1 mW to 2 mW is assumed. However, this numerical range is merely an example.

[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 and unnecessary frequency components removed, if necessary. The transmitting antenna 72 then emits radio waves to the outside. The transmitting antenna 72 is controlled by a microcomputer (controller) 73. The microcomputer (controller) 73 controls the transmission of the transmitting antenna 2 based on a feedback signal from a data transceiver 74, which is based on data received via a data transmitting / receiving antenna 75.

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

[0171] The receiving function, which is composed of a rectifier circuit 82 and a power management unit 83, is controlled by a microcomputer 85 mounted on a part of the PCB or FPC, charges a battery 84, and drives an arbitrary 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 a circuit formed as part of the PCB or FPC. Alternatively, the sensor 86 may be externally connected to the PCB or FPC. The type of the sensor 86 is arbitrary, and may be, for example, a heat sensor, a temperature sensor, an optical sensor, a humidity sensor, a vibration sensor, or the like.

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

[0173] In this way, the antenna 20 can be modularized and is particularly suitable to be configured as a sensor module. The antenna 20 can support two frequency bands while taking advantage of the fact that it can be installed on a metal surface, and therefore is not subject to restrictions due to the material of the installation surface and can be used anywhere, which makes it possible to accommodate miniaturization of the sensor module in particular.

[0174] FIG. 38 is an example of a diagram showing a simulation result of the radio wave efficiency of two antennas. Figure 38 illustrates the simulation results of the radio wave efficiency of the receiving antenna 20 shown in Figure 39, which is equipped with a 2450 MHz (2.45 GHz) data antenna and a 918 MHz power supply antenna, under the usage conditions illustrated in Figure 37. In Fig. 38, the horizontal axis indicates frequency and the vertical axis indicates efficiency (where 1 is 100%). The upper part of Fig. 38 shows the simulation results of the loop antenna 50, and the lower part shows the simulation results of the inverted-F antenna 60. Note that this simulation result corresponds to the electromagnetic field simulation result under ideal conditions (conditions where there are no obstacles blocking the reception of energy) with the distance from the power transmission source to the antenna 1 being 1 m as described above.

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

[0176] Therefore, even if the antenna 20 is configured as a dual-band antenna, mutual interference between the antennas and a decrease in efficiency are avoided. In particular, it was confirmed that the characteristics of the 920 MHz band are not significantly deteriorated on the loop antenna 50 side. Also, it was confirmed that the characteristics of the 2.4 GHz band are not significantly deteriorated on the inverted-F antenna 60 side. Therefore, the antenna 20 of the second embodiment realizes a practical power receiving antenna by using the loop antenna 50, and realizes a practical data communication antenna by using the inverted-F antenna 60.

[0177] As described above, the antenna 20 is configured as a dual-band antenna in which multiple antennas are arranged three-dimensionally. In this case, it has been confirmed that even if a single band is changed to a dual band, an antenna shape can be obtained in which the characteristics of both antennas are less degraded. Therefore, the antenna 20 is expected to achieve overall miniaturization and to exhibit good antenna performance.

[0178] As described above, the antenna 20 according to the second embodiment can supply the received energy to the sensor 86, and can also transmit the energy to any object such as a robot, a device, or a PC. In particular, when applied to FA (Factory Automation), the antenna 20 may be applied to equipment instead of the sensor 86. Furthermore, application to building management is also possible, in which case the antenna 20 may be applied to any member used in close proximity to the human body, such as an employee ID card. Furthermore, the targets of power transmission may also be mobile phones, PDAs (personal digital assistants), wireless microphones, wireless USBs, wireless theaters, wireless televisions, wireless cameras, wireless headphones, wireless mice, wireless keyboards, wireless routers, wireless printers, and the like.

[0179] Next, with reference to Figs. 39 and 40, an implementation example in which the antenna 20 is used to supply power to a device including a sensor to operate it will be described. FIG. 39 is a diagram showing an implementation example in which an antenna is used to supply power to a sensor placed in a device. 39, there is shown a conceptual example in which an antenna 20 is attached to one side of a device 90 shown by a dotted line, making it possible to feed power to a sensor installed in the device 90. This device 90 can be used in place of the sensor 86 shown in FIG. As described above, the loop antenna 50 of the antenna 20 is formed inside the antenna 20, and is designed so that the performance of the antenna is not impaired by the material of the installation surface. Therefore, even if the antenna 20 is directly attached to the metal surface of the device 90, the loop antenna 50 can continue to function.

[0180] In this case as well, the antenna 20 constitutes a power transmitting antenna of a first frequency (e.g., 918 MHz) by a loop antenna 50 made up of a first conductive plate 21, a second conductive plate 22, and a third conductive plate 23. For example, the loop antenna 50 makes it possible to supply power to a device 90. Furthermore, the antenna 20 constitutes a data communication antenna of a second frequency (for example, 2.45 G) by the inverted-F antenna 60. For example, the inverted-F antenna 60 makes it possible to transmit information indicating the state of the device 90 and information measured by a sensor to the outside.

[0181] FIG. 40 is an example of a diagram showing a simulation result of the receiving strength of two antennas. 40(A) and (B) show simulation results of the power receiving state of each antenna in a three-dimensional space in a state where the x-axis direction of the device 90 in Fig. 39 is placed up and the yz plane is placed down (i.e., the device 90 in Fig. 39 is rotated 90 degrees clockwise around the y-axis). Note that this simulation result corresponds to the electromagnetic field simulation result under ideal conditions (conditions where there are no obstacles blocking the reception of energy) with the distance from the power transmission source to the antenna 20 set to 1 m. In Fig. 40(A), the darker the color (the closer to black from gray), the better the power receiving condition. As can be seen from the figure, it was confirmed that the loop antenna 50 can receive energy relatively evenly along the entire length of the antenna 20 composed of the conductive plates 21, 22, and 23.

[0182] 40(B) shows a simulation result of the power receiving state of the inverted-F antenna 60 in a three-dimensional space. Note that this simulation result corresponds to an electromagnetic field simulation result under ideal conditions (when there are no obstacles blocking the reception of energy) with the distance from the power transmission source to the antenna 20 being 1 m. 40(B), similarly, the darker the color (from gray to black), the more favorable the power receiving condition. As can be seen from the figure, since the inverted-F type antenna 60 is biased toward one end of the antenna 20, it was confirmed that energy can be transmitted and received over the entire area of ​​the device 90, even though it is biased toward one end of the entire length of the antenna. In addition, when estimating the power receiving power of the antenna used in this simulation, it was estimated that it is possible to supply about 7.26mW, -21.39dB, and charge the battery with about 3.5mW under the conditions of a power transmission output of 1W and a transmission distance of 1m. However, it should be understood that these figures are merely examples and are not limiting.

[0183] In this way, the antenna 20 realizes a dual-band antenna of the loop antenna 50 (e.g., 918 MHz) and the inverted-F antenna 60 (e.g., 2.45 GHz) by combining antenna patterns of two frequency bands. Furthermore, the antenna 20 can be configured as a multi-band antenna with three or more bands by making it possible to transmit and receive radio waves of other frequencies in addition to the dual bands.

[0184] As described above, the antenna 20 according to the second embodiment integrates antennas for two frequencies, the loop antenna 50 and the inverted-F antenna 60. Although these two antennas are constructed as an integrated unit, they function in such a way that the performance of each antenna is not significantly impaired during use. In addition, 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 the loop antenna 50 and the inverted-F antenna 60 alone, for the following reasons. Since the loop antenna 50 shares a common ground with the power receiving antenna itself, the antenna size is increased and efficiency is improved. In addition, the inverted-F antenna 60 has a hollow space 24 provided for the loop antenna 50, and current passes through both sides of the cut-out window, which contributes to improving the radiation pattern and slightly increasing the radiation efficiency.

[0185] Furthermore, the antenna 20 may be designed so that the installation positions of the loop antenna 50 and the inverted F-shaped antenna 60 are devised to reduce the effect of mutual interference between the antennas and suppress a decrease in the efficiency of each antenna. In addition, the efficiency of each antenna may be improved by, for example, adjusting the impedance of each antenna or matching each antenna so that the efficiency of each antenna is appropriate. For example, a U.FL connector or any matching circuit suitable for use in small devices that require high-frequency transmission may be used. The influence of interference can be reduced by installing the inverted-F antenna 60 at a position far from the feeder 25. Also, the influence of interference can be reduced by installing it at a position where the current of the power receiving antenna 50 is small (at the node position of the λ / 4 resonance).

[0186] The antenna 20 according to the second embodiment has been described above with reference to FIGS. The antenna 20 according to the second embodiment can be implemented in various ways. Aspect 1 In its simplest implementation, the antenna 20 can be configured as an antenna including at least the loop antenna 50. The antenna 20 can be configured as a single-band antenna consisting of the loop antenna 50. In some implementations, the loop antenna 50 may be further combined with a rectifier (or rectifier circuit 82, etc.).

[0187] Aspect 2 The implementation of the antenna 20 includes at least a combination of the loop antenna 50 and a rectifier (or a rectifier circuit 82), and the impedance of the antenna can be adjusted to obtain high efficiency. In this case, matching with variations in the size and shape of the antenna 20, frequency compatibility, etc. may be performed.

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

[0189] Aspect 4 An inverted-F antenna 60 may be further added to the third embodiment. In this case, the inverted-F antenna 60 allows application to high frequencies, for example, to the 2.4 GHz band. In this case, the antenna pattern portion of the inverted-F antenna 60 may be adjusted in various ways (see Figs. 36(A) to (C)). Also, the mounting position of the inverted-F antenna 60 may be adjusted in various ways (see Figs. 36(B) and (D)). Various adjustments can be made so that the antenna pattern portion of the inverted-F antenna 60 can have an appropriate shape.

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

[0191] Aspect 6 In each of the first to fifth embodiments, a core material 30 may be further combined inside the antenna 20. In this case, the size, shape, and characteristics of each antenna may be adjusted by adjusting the material, size, shape, and the like of the core material. In this case, the antenna 20 may utilize an FPC.

[0192] As described above, the present invention provides an antenna, rectenna, and circuit module that can receive one or more bands, is small and low-profile, and has few restrictions on its installation location, making it possible to provide antenna modules, sensor modules, and the like that are compatible with a wide range of small sensing applications.

[0193] In the first embodiment, various types of power receiving antennas 1, 1A, and 1a to 1h have been described with reference to FIGS. 1 to 31 and 42. FIG. In the second embodiment, various configurations of the power receiving antenna 20 have been described with reference to FIGS. The first and second embodiments may be implemented independently of each other, or may be implemented in combination with each other. For example, the core material 30 and the inverted-F antenna 60 according to the second embodiment can be applied to the power receiving antennas 1, 1A, and 1a to 1h according to the first embodiment. Similarly, the description of the first embodiment can be applied to the second embodiment.

[0194] The communication band used for power supply is not limited to the 920 MHz band, but may be, for example, the UHF band, such as the 868 MHz band used in Europe and the 915 MHz band in the United States, or any other frequency band belonging to the UHF band. Furthermore, the communication band for data communication is not limited to the 2.4 GHz band, and a frequency band in the range of (±10%) around 2.4 GHz may be used. For example, the 2.45 GHz band may be used. A communication band in the range of around 5.7 GHz may also be used. While a high frequency band is required for high-speed data communication, a lower frequency band can be used for power supply compared to data communication.

[0195] The present invention is not limited to the above-described embodiments, and includes various modified examples. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration. The above-described embodiments disclose at least the configurations 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; a second conductive plate at least partially opposed to the first conductive plate; a feeder that connects a first end of the first conductive plate and a second end of the second conductive plate and is provided on approximately the same plane as the first conductive plate; a conductive member connecting a first other end portion of the first conductive plate opposite the first end portion and a second other end portion of the second conductive plate opposite the second end portion; a first antenna comprising: A receiving antenna for use in wireless power supply comprising:

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

3. A receiving antenna as described in Claim 2, characterized in that the second conductive plate and the plate-shaped conductive member are integrally molded.

4. A receiving antenna as described in claim 2, characterized in that the second conductive plate and the conductive member are constructed in a state in which a single conductive plate is folded.

5. 5. The power receiving antenna according to claim 4, wherein the one conductive plate is configured with a part thereof cut out.

6. the first conductive plate has a central portion in a longitudinal direction thereof protruding in a stepped shape toward the second conductive plate; The second conductive plate has a central portion in a longitudinal direction that protrudes in a stepped shape toward the first conductive plate.

6. The power receiving antenna according to claim 1, wherein the power receiving antenna is a power receiving antenna.

7. 6. The power receiving antenna according to claim 1, wherein the plate-shaped conductive plate is configured with a portion cut out.

8. 8. The power receiving antenna according to claim 7, wherein at least one of the first conductive plate and the second conductive plate is provided with a slot.

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

10. 10. The power receiving antenna according to claim 9, wherein a gap is provided between the tip of the protrusion and the second conductive plate.

11. 6. The power receiving antenna according to claim 1, wherein a dielectric core material is filled between the first conductive plate and the second conductive plate.

12. a cut-out area is provided in the first conductive plate, and a second antenna is disposed therein; The receiving antenna according to any one of claims 1 to 5.

13. The first antenna functions as a loop antenna. The receiving antenna according to any one of claims 1 to 5.

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

15. The first antenna is an antenna for receiving power. The receiving antenna according to any one of claims 1 to 5.

16. The first antenna is driven in a frequency range of about 920 MHz. The receiving antenna according to any one of claims 1 to 5.

17. The second antenna is an inverted-F antenna. The receiving antenna according to claim 12.

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

19. The second antenna operates in a frequency range of about 2.4 GHz. The receiving antenna according to claim 12.

20. 6. The power receiving antenna according to claim 1, wherein a dielectric core material is filled between the first conductive plate and the second conductive plate.

21. The first conductive plate is formed of a first conductive layer of a flexible printed circuit board (FPC), and the inverted-F antenna is formed 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 any one of claims 1 to 5.

23. a width of the first conductive plate and a 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 20% longer than the length at which the frequency band of radio waves to be received is a resonant frequency. The receiving antenna according to any one of claims 1 to 5.

24. a width of the first conductive plate and a 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 shorter by 10 to 30%, preferably by about 20%, than the length at which the frequency band of radio waves to be received is a resonant frequency. The receiving antenna according to any one of claims 1 to 5.

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