Space electromagnetic energy harvesting metamaterial antennas, antenna arrays and conversion systems

Abstract

The present invention discloses a space electromagnetic energy collection metamaterial antenna, antenna array and conversion system. The antenna includes a first dielectric substrate, a radiation layer, a grounding plate and a coaxial cable. The radiation layer and the grounding plate are respectively laid on the upper and lower sides of the first dielectric substrate. The radiation layer is a W-shaped patch composed of four open-loop resonators back to back. A feeding hole that runs through the first dielectric substrate is provided. The feeding hole is located at the center of the radiation layer. The feeding layer is laid on the inner wall of the feeding hole. The feeding layer is electrically connected to the radiation layer. The grounding plate is provided with an avoidance position near the feeding hole. The W-shaped radiation layer is formed by four open-loop resonators back to back, so that the antenna structure as a whole presents the properties of a magnetic single negative electromagnetic metamaterial, and has good directivity, wide frequency band, small standing wave ratio, and is easy to match impedance, so that electromagnetic energy in more frequency bands can be collected, and it is easy to form impedance matching with a rectifier amplifier circuit to meet the requirements of collecting space electromagnetic energy.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a space electromagnetic energy collection metamaterial antenna, an antenna array and a conversion system. Background Art

[0002] With the development of modern society, the Internet of Things technology has made great progress. The scope of industries involved has also expanded from traditional logistics and retail industries to meteorology, industry, agriculture, and medical industries. It has even penetrated into our lives. Technologies such as smart homes and autonomous driving are all based on the Internet of Things. As the basic equipment in the Internet of Things system, wireless sensors need to be able to work stably for a long time. For a complex and large wireless sensor network, the energy supply problem of each wireless sensor node is an urgent problem to be solved.

[0003] Battery power is the most commonly used power supply method, but wireless sensor nodes are scattered, and when maintenance and replacement are required, there are problems such as difficulty in replacement, high labor costs and low replacement efficiency. Therefore, collecting energy from the environment has become a research hotspot, and collecting electromagnetic energy from space is an environmental energy collection technology that cannot be ignored. This method is to collect electromagnetic signals in space through antennas, and then convert the electromagnetic energy into alternating current, and then convert it into direct current through rectification and amplification steps to power the sensor. Since the space we live in is full of electromagnetic energy of different frequency bands, the collection of electromagnetic energy can be completed anywhere. This method is green and pollution-free, reduces the emission of carbon dioxide and chemical substances in batteries, and protects the environment.

[0004] However, the inventors of this application found that the above technology has at least the following problems in the process of implementing the technical solution of the invention in the embodiment of this application:

[0005] Most of the existing antennas for collecting electromagnetic energy are large in size, which is not conducive to on-site installation and affects the use of wireless sensors. In addition, the energy collection efficiency is not very high and the stable operation of wireless sensors cannot be guaranteed. Summary of the invention

[0006] The purpose of the present invention is to provide a space electromagnetic energy collection metamaterial antenna to solve the technical problems mentioned in the background technology. The purpose of the present invention is achieved through the following technical solutions:

[0007] The invention discloses a space electromagnetic energy collection metamaterial antenna, comprising a first dielectric substrate, a radiation layer, a grounding plate and a coaxial cable, wherein the radiation layer is laid on the upper side of the first dielectric substrate, and is a W-shaped patch composed of four open-ring resonators arranged back to back; a feeding hole penetrating from top to bottom is provided on the first dielectric substrate, the feeding hole is located at the center of the radiation layer, a feeding layer is laid on the inner wall of the feeding hole, and the feeding layer is electrically connected to the radiation layer; the grounding plate is laid on the lower side of the first dielectric substrate, and a avoidance position is arranged on the grounding plate near the feeding hole; the inner conductor of the coaxial cable is electrically connected to the feeding layer, and the outer conductor of the coaxial cable is electrically connected to the grounding plate.

[0008] Furthermore, the first dielectric substrate is a rectangular plate made of FR4 material, and the relative dielectric constant of the first dielectric substrate is 4.4.

[0009] Furthermore, the ground plate is a copper sheet having the same size as the first dielectric substrate, and the thickness of the ground plate is 0.017 mm.

[0010] Furthermore, the coaxial cable is connected to an SMA connector, and the SMA connector is an N female connector.

[0011] The present invention also discloses an antenna array having any of the above-mentioned metamaterial antennas, including a second dielectric substrate and a combiner, wherein the metamaterial antenna array is arranged on the upper side of the second dielectric substrate, the combiner is laid on the lower side of the second dielectric substrate, and through holes are opened on the second dielectric substrate, the through holes correspond to the feeding holes one by one, and the feeding layer is electrically connected to the combiner through the through holes.

[0012] The present invention also discloses a conversion system having the above antenna array, including a matching circuit, a rectifying circuit, and a power management circuit. The antenna array is electrically connected to the matching circuit, the rectifying circuit is electrically connected to the matching circuit, and the power management circuit is electrically connected to the rectifying circuit.

[0013] The technical solution provided in the embodiments of the present application has at least the following technical effects or advantages:

[0014] By forming a W-shaped radiation layer with four open-ring resonators back to back, the antenna structure as a whole presents the properties of a magnetic single negative electromagnetic metamaterial, which has good directivity, wide bandwidth, small standing wave ratio, and is easy to match impedance. It can collect electromagnetic energy in more frequency bands and easily form impedance matching with the rectifier amplification circuit to meet the requirements of collecting electromagnetic energy in space. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings in the specification, which constitute a part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 This is a schematic diagram of the structure of the metamaterial antenna in Example 1 of the present application;

[0017] Figure 2 This is a cross-sectional view of the metamaterial antenna in Example 1 of the present application;

[0018] Figure 3 This is the equivalent circuit diagram of the metamaterial antenna in Example 1 of the present application;

[0019] Figure 4 This is a graph showing the amplitudes of the parameters S11 and S21 of the metamaterial antenna in Example 1 of the present application;

[0020] Figure 5 This is a diagram of the effective dielectric constant of the metamaterial antenna in Example 1 of the present application;

[0021] Figure 6 This is the effective magnetic permeability diagram of the metamaterial antenna in Example 1 of the present application;

[0022] Figure 7 This is a front view schematic diagram of the antenna array of Example 2 of the present application;

[0023] Figure 8 This is a schematic diagram of the back side of the antenna array of Embodiment 2 of the present application;

[0024] Fig. 9 This is the schematic diagram of the conversion system circuit of Example 3 of the present application.

[0025] Fig.10 This is a structural diagram of the matching circuit of Example 3 of the present application.

[0026] Fig.11 This is a structural diagram of the rectifier circuit of Example 3 of the present application.

[0027] Fig.12 This is a structural diagram of the power management circuit of Example 3 of the present application.

[0028] Markings in the attached figure: 1, radiation layer; 2, first dielectric substrate; 3, grounding plate; 31, avoidance position; 4, feeding hole; 5, feeding layer; 6, second dielectric substrate; 7, combiner. DETAILED DESCRIPTION

[0029] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings and specific implementation methods of the specification. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] The purpose of the present invention is to provide a metamaterial antenna for collecting space electromagnetic energy to solve the technical problems mentioned in the background technology. The purpose of the present invention is achieved through the following technical solutions:

[0032] like Figure 1 , Figure 2 The shown space electromagnetic energy collection metamaterial antenna comprises a radiation layer 1, a first dielectric substrate 2, a grounding plate 3 and a coaxial cable (not shown). The radiation layer 1 is a copper metal layer laid on the upper surface of the first dielectric substrate 2. The radiation layer 1 is a W-shaped structure composed of four open-ring resonators back to back. The radiation layer 1 is located at the center of the first dielectric substrate 2. The first dielectric substrate 2 is a rectangular plate made of FR4 material. The first dielectric substrate 2 is provided with a feeding hole 4 that passes through from top to bottom. The feeding hole 4 is located at the center of the radiation layer 1. The inner wall of the feeding hole 4 is plated with a conductive feeding layer 5, and the feeding layer 5 is connected to the radiation layer 1. The grounding plate 3 is a copper sheet laid on the lower surface of the first dielectric substrate 2. The grounding plate 3 is provided with an avoidance position 31 near the feeding hole 4, so that the grounding plate 3 is not connected to the feeding layer 5. The inner conductor of the coaxial cable is electrically connected to the feeding layer 5, the outer conductor of the coaxial cable is electrically connected to the grounding plate 3, and the other end of the coaxial cable is connected to the SMA connector, which is an N female connector. Realize the feeding of metamaterial antenna.

[0033] Specifically, the length of the radiation layer 1 is 28.98 mm, the width is 28 mm, the gap at the opening of the radiation layer is 2 mm, the width of the microstrip line of the radiation layer 1 is 7.02 mm, and the lengths of the microstrip lines on both sides of the radiation layer 1 are 8 mm, 14 mm, and 8 mm from top to bottom, respectively; the length of the first dielectric substrate 2 is 57.96 mm, the width is 28 mm, and the relative dielectric constant is 4.4; the radius of the feeding hole 4 is 0.6 mm; the length of the ground plate 3 is 57.96 mm, the width is 28 mm, and the thickness is 0.017 mm, and the avoidance position 31 is a circle with a radius of 1.6 mm.

[0034] like Figure 3 As shown, the equivalent circuit of the metamaterial antenna of the embodiment of the present application is a double-loop mirror-symmetrical design. This type of design can make the antenna exhibit metamaterial properties. The antenna with metamaterial properties is conducive to the miniaturization of the antenna and the improvement of gain.

[0035] Figure 4 The following is a curve diagram of the input return loss S11 and the forward transmission coefficient S21 parameters of the metamaterial antenna of the present application embodiment. Figure 4 It can be seen that the resonant frequency of the metamaterial antenna is 2.45 GHz, and it has a wide bandwidth near the resonant frequency. It can be seen that the metamaterial antenna has good characteristics and can effectively collect electromagnetic waves in the communication frequency band, meeting the requirements of wireless energy harvesting devices for electromagnetic energy collection.

[0036] Figure 5 This is a graph of the effective dielectric constant of the metamaterial antenna of the present application. The data is derived from the above S11 and S21 parameters, and then the above two parameters are inverted using the Smith algorithm using MATLAB software to successfully obtain the effective dielectric constant curve of the antenna. Figure 5 The solid line is the real part, and the dotted line is the imaginary part. It can be clearly seen that around 2.45 GHz, the imaginary part of the effective dielectric constant is negative.

[0037] Figure 6 This is a graph of the effective magnetic permeability of the metamaterial antenna of the embodiment of the present application. Similar to the above, after inversion of the Smith algorithm, the effective magnetic permeability curve of the antenna is successfully obtained. Figure 6 The solid line is the real part, and the dotted line is the imaginary part. It can be clearly seen that near 2.45 GHz, the imaginary part of the effective permeability is negative.

[0038] Through the values ​​of the above effective dielectric constant and effective magnetic permeability curves, it can be concluded that the antenna of the embodiment of the present application meets the properties of a metamaterial antenna.

[0039] Specifically, the Smith algorithm is as follows:

[0040]

[0041]

[0042]

[0043] μ=n*Z

[0044] Where: n is the refractive index, Z is the wave impedance, k is the wave number, d is the thickness of the substrate through which the electromagnetic wave passes, ε is the effective dielectric constant, and μ is the effective magnetic permeability. The effective dielectric constant and effective magnetic permeability of the antenna can be inverted by calculating the above formula.

[0045] Example 2

[0046] like Figure 7 , Figure 8As shown, an antenna array with the above-mentioned metamaterial antenna includes a radiation layer 1, a first dielectric substrate 2, a grounding plate 3, a second dielectric substrate 6 and a combiner 7 arranged in sequence. 16 W-shaped radiation layers 1 are laid on the first dielectric substrate 2 in a 4×4 array. The radiation layer 1, the first dielectric substrate 2, the grounding plate 3, and the second dielectric substrate 6 are all provided with penetrating feeding holes 4. The feeding holes 4 correspond to the center of the radiation layer 1 one by one. The feeding holes 4 are plated with conductive feeding layers 5. The feeding layers 5 realize the electrical connection between the radiation layer 1 and the combiner 7. Among them, the grounding plate 3 is provided with an avoidance position 31 at the feeding hole 4 to avoid the electrical connection between the feeding layer 5 and the grounding plate 3. A guide outlet is provided on the side of the antenna array. The inner conductor of the coaxial cable is connected to the combiner 7, and the outer conductor is connected to the grounding plate 3. The collected energy is combined and output on the side of the antenna array.

[0047] Example 3

[0048] like Fig. 9 As shown, a conversion system with the above-mentioned antenna array includes a matching circuit, a rectifier circuit, a power management circuit and a load, the antenna array is electrically connected to the matching circuit, the rectifier circuit is electrically connected to the matching circuit, the power management circuit is electrically connected to the rectifier circuit, and the load is electrically connected to the power management circuit.

[0049] like Fig.10 As shown in the figure, the matching circuit adopts a double-branch structure. The double-branch structure is not limited to a single matching path but has countless matching paths to achieve the matching of the initial impedance to the target impedance. This also makes it have certain advantages in the flexibility of component parameter selection and working bandwidth.

[0050] like Fig.11 As shown, the rectifier circuit adopts a single-stage voltage doubler rectifier circuit. It has a high conversion efficiency and the output is also twice that of the half-wave rectifier structure. At the same time, the overall output voltage is twice the input voltage, which can better collect low-voltage energy.

[0051] like Fig.12 As shown in the figure, the power management circuit uses the TPS6120 low input voltage synchronous boost converter. The input port of the chip is connected to the output port of the rectifier circuit. At low load current, the converter can be switched to power saving mode to maintain high efficiency over a large load current range. When the DC voltage output by the rectifier circuit reaches the minimum threshold of the chip input, the chip starts and charges C2 through the DC boost circuit inside the chip. When Vout is greater than 1.8V, the OUT port starts to discharge until VOUT drops to the stop voltage. It can be used for battery power supply.

[0052] The purpose of the matching circuit is to make the characteristic impedance of the transmission line equal to the equivalent load impedance, to achieve maximum energy transmission, and thus to maximize the transmission of the collected energy to the load end. The rectifier circuit is responsible for converting high-frequency AC small signals into DC power with a higher voltage. Since the ambient RF energy is usually of very low energy level and usually cannot provide long-term continuous operation for the load, we need to use the power management circuit to store the collected power in energy storage elements, such as supercapacitors or lithium batteries, and perform appropriate management to enable the load to work periodically.

[0053] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0054] By forming a W-shaped radiation layer with four open-ring resonators back to back, the antenna structure as a whole presents the properties of a magnetic single negative electromagnetic metamaterial, which has good directivity, wide bandwidth, small standing wave ratio, and is easy to match impedance. It can collect electromagnetic energy in more frequency bands and easily form impedance matching with the rectifier amplification circuit to meet the requirements of collecting electromagnetic energy in space.

[0055] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0056] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0057] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0058] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A space electromagnetic energy collection metamaterial antenna, comprising a first dielectric substrate, a radiation layer, a ground plate and a coaxial cable, characterized in that: The radiation layer is laid on the upper side of the first dielectric substrate, and the radiation layer is a W-shaped patch composed of four open-ring resonators back to back; a feeding hole is opened on the first dielectric substrate and runs through from top to bottom, and the feeding hole is located at the center of the radiation layer. A feeding layer is laid on the inner wall of the feeding hole, and the feeding layer is electrically connected to the radiation layer; the grounding plate is laid on the lower side of the first dielectric substrate, and the grounding plate is equal in size to the first dielectric substrate, and a avoidance position is arranged on the grounding plate near the feeding hole; the inner conductor of the coaxial cable is electrically connected to the feeding layer, and the outer conductor of the coaxial cable is electrically connected to the grounding plate.

2. The space electromagnetic energy harvesting metamaterial antenna according to claim 1, characterized in that: The first dielectric substrate is a rectangular plate made of FR4 material, and the relative dielectric constant of the first dielectric substrate is 4.

4.

3. The space electromagnetic energy harvesting metamaterial antenna according to claim 1, characterized in that: The grounding plate is a copper sheet, and the thickness of the grounding plate is 0.017 mm.

4. The space electromagnetic energy harvesting metamaterial antenna according to claim 1, characterized in that: The coaxial cable is connected to an SMA connector, and the SMA connector is an N female connector.

5. An antenna array having the metamaterial antenna according to any one of claims 1 to 4, characterized in that: The invention comprises a second dielectric substrate and a combiner, wherein the metamaterial antenna array is arranged on the upper side of the second dielectric substrate, the combiner is laid on the lower side of the second dielectric substrate, a through hole is opened on the second dielectric substrate, the through hole corresponds to the feeding hole one by one, and the feeding layer is electrically connected to the combiner through the through hole.

6. A conversion system having an antenna array as claimed in claim 5, characterized in that: It includes a matching circuit, a rectifying circuit, and a power management circuit. The antenna array is electrically connected to the matching circuit, the rectifying circuit is electrically connected to the matching circuit, and the power management circuit is electrically connected to the rectifying circuit.

Images