Metaloop rectification antenna of coplanar integrated solar cell

Abstract

The invention discloses a metaloop rectification antenna of a coplanar integrated solar cell. The metaloop rectification antenna comprises a dielectric substrate, an annular metal layer is arranged on the upper surface of the dielectric substrate, and a metal grounding plate is arranged on the lower surface of the dielectric substrate; a solar cell is arranged in the middle of the annular metal layer; a rectifying circuit is arranged on the lower surface of the metal grounding plate; the annular metal layer is connected with a rectification circuit, and the solar cell and the output end of the rectification circuit are connected with a load. Since the current distribution is only concentrated on the ring and the solar cell is placed in the center of the ring without influencing the performance of the antenna, the rectification antenna and the solar cell can collect radio frequency energy and light energy at the same time without interfering with each other. The resonant frequency of the antenna can be changed by adjusting the interdigital structures and the using number of the metamaterial units, the current passing through the antenna loop has a negative phase constant, the height of the antenna is effectively reduced, and the area of the antenna is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of rectennas, and in particular to a metaloop rectenna with coplanar integrated solar cells. Background Art

[0002] With the continuous growth of global energy demand, many problems have begun to appear in the energy structure dominated by fossil fuels, so people are in urgent need of finding some clean energy to replace fossil fuels. The environment in which people live is always full of energy from microwave signals, sunlight, wind flow, water flow and various vibrations. The effective collection and utilization of these energies has gradually become a feasible and effective solution to solve the world energy crisis. In the collection of environmental energy, people have found that the collection and utilization of a single energy source is often accompanied by many limitations. Once these energies in the environment fluctuate, it is bound to affect the power supply. In order to make the collected energy stable enough, people began to combine the collection devices of multiple different energy sources, thus obtaining a hybrid energy collection device that can collect multiple energies at the same time. Since the ubiquitous radio frequency energy and light energy in today's life are the first choice for people to collect environmental energy, how to combine the rectifying antennas that collect these two energies with solar cells has become the focus of people's research.

[0003] Since the 1990s, many scholars have explored RF-Solar hybrid energy harvesting technology. Since the energy in the environment is often small and people's demand for miniaturization and integration of electronic devices is increasing, how to balance the contradiction between the mutual influence between the rectenna and the solar cell and the miniaturization and integration of the entire system has become the focus of research and design.

[0004] The prior art "A Partially Transparent GSM Band Loop RF-Solar Energy Harvester" discloses a partially transparent GSM band ring energy harvester. The energy harvester uses a zigzag square ring antenna designed on a transparent acrylic plate, and light can pass through the transparent part in the center of the antenna ring to illuminate the solar cell below the antenna. However, due to the high profile of the antenna, the solar cell is placed at the bottom of the entire system. Therefore, the collection system not only has a high profile, but the antenna part also has a certain shielding of the solar cell, which limits its application scenarios. The prior art "Circularly Polarized Broadside Beam Radiated From a Large, Low-Profile Metaloop Antenna" proposes a low-profile metaloop antenna. However, the antenna is large in size and is not conformally integrated with the solar cell, and is only used for communication. The prior art "An Optically Transparent Metantennafor RF Wireless Energy Harvesting" proposes a new transparent metasurface antenna based on ITO material. The antenna is transparent as a whole, achieving a balance between electrical properties and light transmittance. However, the antenna is large in size, and the substrate still blocks part of the light, affecting the collection efficiency of the solar cell. The prior art "A compact hybrid solarand electromagnetic energy harvester at 2.45GHz microstrip rectenna" proposes a hybrid energy harvester that places a mesh antenna on a solar cell. The collection system places the rectifier circuit on the back of the solar cell, with a high degree of integration. However, the gain of the rectenna is low, and it blocks part of the solar cell. Summary of the invention

[0005] The purpose of the present invention is to provide a metaloop rectenna with coplanar integrated solar cells, which solves the above technical problems and realizes hybrid energy collection without interference between radio frequency energy and solar energy, as well as miniaturization and integration of the entire system.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A metaloop rectifier antenna with coplanar integrated solar cells comprises a dielectric substrate, wherein an annular metal layer is provided on the upper surface of the dielectric substrate and a metal grounding plate is provided on the lower surface;

[0008] A solar cell is provided in the middle of the annular metal layer, and a rectifier circuit is provided on the lower surface of the metal ground plate;

[0009] The annular metal layer is connected to a rectifier circuit, and the output ends of the solar cell and the rectifier circuit are both connected to a load.

[0010] In a specific embodiment, the annular metal layer is formed by a plurality of metamaterial units closely surrounding the solar cell and connected in sequence to form an I-shaped shape, with a gap left at the ends of the ends. The end of the annular metal layer serves as an output port for the energy collected by the antenna. The periodically arranged metamaterial units can obtain left-handed material properties, generate resonance and effectively reduce the height of the antenna.

[0011] In a specific embodiment, the metamaterial unit includes a g-shaped metal patch, metal interdigital patches are arranged on both sides of the g-shaped metal patch, and two interdigital capacitors are formed between the g-shaped metal patch and the metal interdigital patches.

[0012] In a specific embodiment, a first through hole is provided at the upper end of the L-shaped metal patch, and the L-shaped metal patch is connected to the metal ground plate through the first through hole to achieve a ground short circuit effect.

[0013] In a specific embodiment, the solar cell includes a film and a solar cell body, the solar cell body is wrapped in the film, and pins are provided at both ends of the solar cell body for outputting the collected energy.

[0014] In a specific embodiment, the rectifier circuit includes a first matching branch, a rectifier diode circuit and a pass filter connected in sequence, and the pass filter is used to filter and suppress high-order harmonics.

[0015] In a specific embodiment, the rectifier diode circuit includes a capacitor C1, one end of the capacitor C1 is connected to the third matching branch, and then a diode D1 is connected in parallel, and the diode D1 is connected in series with the second matching branch.

[0016] In a specific embodiment, a third through hole is provided at the end of the annular metal layer, a second through hole is provided at the input end of the first matching branch, and the annular metal layer is connected to the rectifier circuit through the third through hole and the second through hole in sequence.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention has the characteristic that a solar cell can be placed in the center of the ring without affecting the antenna performance because its current distribution is only concentrated on the ring. Therefore, the rectenna and the solar cell can collect radio frequency energy and light energy at the same time without interfering with each other. The resonant frequency of the antenna can be changed by adjusting the interdigital structure and the number of metamaterial units used. The current passing through the antenna ring has a negative phase constant and satisfies -1<β / k 0 <0, effectively reducing the height of the antenna. Since the gain of the electrically large loop antenna is mainly related to the circumference of the antenna ring, the antenna ring can be bent according to the shape of the solar cell used, reducing the area of ​​the antenna. The present invention simultaneously achieves the purpose of non-interference between the rectifying antenna and the solar cell and miniaturization and integration of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 is a top view schematic diagram of the antenna structure of the present invention;

[0021] Figure 3 It is a schematic diagram of the structure of the metamaterial unit of the present invention;

[0022] Figure 4 It is a schematic structural diagram of the annular metal layer of the present invention;

[0023] Figure 5 It is a schematic structural diagram of a solar cell of the present invention;

[0024] Figure 6 It is a structural schematic diagram of a rectifier circuit of the present invention;

[0025] Figure 7 is a dispersion diagram of the metamaterial unit of the present invention;

[0026] Figure 8 It is a schematic diagram of simulation results of the S parameters of the antenna of the present invention changing with frequency;

[0027] Fig. 9 It is a schematic diagram of simulation results showing that the rectification efficiency of the rectification circuit of the present invention varies with frequency.

[0028] As shown in the figure:

[0029] 1. dielectric substrate, 2. annular metal layer, 3. solar cell, 4. metal ground plate, 5. first through hole, 6. via hole, 7. metal interdigital patch, 8. letter-shaped metal patch, 9. interdigital capacitor, 12. first matching branch, 13. rectifier diode circuit, 14. pass-through filter, 15. second through hole, 16. third through hole, 17. second matching branch, 18. third matching branch, 301. solar cell body, 302. film, 304. pin. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] See also Figure 1 - Figure 2 A metaloop rectifier antenna with a coplanar integrated solar cell comprises a dielectric substrate 1, wherein an annular metal layer 2 is provided on the upper surface of the dielectric substrate 1, and a metal grounding plate 4 is provided on the lower surface.

[0032] The dielectric substrate 1 is cylindrical, made of Rogers RT / duroid 5880 (tm), with a radius of 60 mm and a thickness of 0.508 mm. The diameter of the dielectric substrate 1 is larger than the length and width of the annular metal layer 2, in order to increase the metal grounding layer to increase reflection and improve the gain of the antenna.

[0033] A solar cell 3 is provided in the middle of the annular metal layer 2, and a rectifier circuit is provided on the lower surface of the metal ground plate 4;

[0034] The annular metal layer 2 is connected to a rectifier circuit, and the output end of the solar cell 3 is connected to a load.

[0035] The annular metal layer 2 is composed of 31 metamaterial units that are closely connected around the solar cell 3 to form an I-shaped shape, and a gap is left at the ends of the annular metal layer 2. Since the gain of the annular metal layer 2 is related to its circumference rather than its area, this shape can be used to reduce the area of ​​the antenna as much as possible without changing the length, thereby miniaturizing the antenna. The length of the 31 metamaterial units will resonate at 2.45GHz. A third through hole 16 is provided at the end of the annular metal layer 2 as an output port for the energy collected by the antenna, which is used to connect the annular metal layer 2 to the rectifier circuit.

[0036] The metamaterial unit includes an I-shaped metal patch 8, and metal finger patches 7 are arranged on both sides of the I-shaped metal patch 8. The fingers arranged on the metal finger patches 7 match the fingers arranged on the I-shaped metal patch 8, and two finger capacitors 9 are formed between the matched I-shaped metal patch 8 and the metal finger patches 7. The I-shaped metal patches 8 are all arranged with their backs to the solar cell 3, that is, the first through hole 5 is arranged outside the I-shaped shape. The periodically arranged metamaterial unit can obtain the same properties as the left-handed material, that is, it can generate resonance and effectively reduce the height of the antenna.

[0037] like Figure 3-Figure 4 As shown, the specific dimensions of the metamaterial unit are p=10mm, w=4.5mm, L=6mm, r=0.4mm, and d=1.6mm. The letter-shaped metal patch 8 is provided with a first through hole 5, and a via hole 6 matching the first through hole 5 is provided on the dielectric substrate 1 at a position corresponding to the first through hole 5. The letter-shaped metal patch 8 is connected to the metal ground plate 4 through the first through hole 5 to achieve a ground short circuit effect.

[0038] like Figure 5 As shown, the solar cell 3 is located in the center of the area surrounded by the annular metal layer 2. The solar cell 3 includes a film 302 and a solar cell body 301. The solar cell body 301 is wrapped in the film 302. A metal grid is also provided inside the solar cell body 301. Pins 304 are provided at both ends of the solar cell body 301. In this embodiment, a 50mm×10mm solar cell is selected for integration with the antenna. The solar cell body 301 has a thickness of 0.55mm and a dielectric constant of 5.95. The PET film 302 has a thickness of 0.2mm and a dielectric constant of 2.893. Pins 304 are used to output the collected energy, and both the pins and the metal grid are made of pec material.

[0039] like Figure 6 As shown, the rectifier circuit includes a first matching branch 12, a rectifier diode circuit 13 and a pass filter 14 which are connected in sequence.

[0040] The rectifier diode circuit 13 includes a capacitor C1, one end of which is connected to the third matching branch 18, and then connected in parallel with a diode D1, and the diode D1 is connected in series with a second matching branch 17. The direct-through filter 14 includes a microstrip line and a fan-shaped open branch, which can be regarded as a parallel capacitor to filter and suppress high-order harmonics.

[0041] The annular metal layer 2 is connected to the rectifier circuit in sequence through the third through hole 16 and the second through hole 15. The output end of the rectifier circuit is connected to a load.

[0042] Figure 7 The dispersion curve of the metamaterial unit is shown in FIG. 1 . In this embodiment, the β / k corresponding to the resonant frequency of 2.45 GHz is 0 = -0.61, where β is the phase constant of the current passing through the antenna loop, k 0 is the free space wave number; the metaloop antenna designed in this way meets the characteristics of left-handed materials and large electric loops.

[0043] Figure 8The curve of S parameter variation of metaloop antenna integrated with solar cell with frequency shows that the antenna can work well when |S11| is less than -10dB at 2.45GHz.

[0044] Fig. 9 The curve of the rectification efficiency of the rectification circuit at 2.45GHz versus input power shows that the rectification circuit has a rectification efficiency of 63% at an input of 0dBm, and can effectively convert the AC power collected by the antenna into DC power.

[0045] The present invention can work normally in three situations:

[0046] The first case: When there is only light in the environment, the solar cell will absorb the light and connect the DC power to the load that needs to be powered.

[0047] The second situation: When there is only RF signal in the environment, the antenna will absorb RF energy and transmit AC power to the rectifier circuit, and then connect the DC power obtained in the rectifier circuit to the load that needs energy.

[0048] The third situation: When there is light and RF signals in the environment at the same time, since the rectifying antenna and the solar cell do not interfere with each other, the two will respectively connect the collected DC power to the load that needs energy.

Claims

1. A metaloop rectenna with coplanar integrated solar cells, characterized in that: It comprises a dielectric substrate (1), wherein the upper surface of the dielectric substrate (1) is provided with an annular metal layer (2), and the lower surface is provided with a metal grounding plate (4); A solar cell (3) is provided in the middle of the annular metal layer (2), and a rectifier circuit is provided on the lower surface of the metal ground plate (4); The annular metal layer (2) is connected to a rectification circuit, and the solar cell (3) and the output end of the rectification circuit are both connected to a load.

2. The metaloop rectenna of a coplanar integrated solar cell according to claim 1, characterized in that: The annular metal layer (2) is composed of a plurality of metamaterial units connected in sequence around a solar cell (3) to form an I-shaped shape, with a gap left at the ends of the folded ends.

3. The metaloop rectenna of a coplanar integrated solar cell according to claim 2, characterized in that: The metamaterial unit comprises a letter-shaped metal patch (8), metal interdigital patches (7) are arranged on both sides of the letter-shaped metal patch (8), and two interdigital capacitors (9) are formed between the letter-shaped metal patch (8) and the metal interdigital patches (7).

4. The metaloop rectenna with coplanar integrated solar cell according to claim 3, characterized in that: A first through hole (5) is provided at the upper end of the letter-shaped metal patch (8), and the letter-shaped metal patch (8) is connected to the metal grounding plate (4) through the first through hole (5).

5. The metaloop rectenna with coplanar integrated solar cell according to claim 1, characterized in that: The solar cell (3) comprises a film (302) and a solar cell body (301); the solar cell body (301) is wrapped in the film (302); and pins (304) are provided at two ends of the solar cell body (301).

6. The metaloop rectenna with coplanar integrated solar cell according to claim 1, characterized in that: The rectifier circuit comprises a first matching branch (12), a rectifier diode circuit (13) and a straight-through filter (14) which are connected in sequence.

7. The metaloop rectenna with coplanar integrated solar cell according to claim 6, characterized in that: The rectifier diode circuit (13) comprises a capacitor C1, one end of which is connected to a third matching branch node (18), and then a diode D1 is connected in parallel, and a second matching branch node (17) is connected in series to the diode D1.

8. The metaloop rectenna with coplanar integrated solar cell according to claim 6, characterized in that: A third through hole (16) is provided at the end of the annular metal layer (2), a second through hole (15) is provided at the input end of the first matching branch (12), and the annular metal layer (2) is connected to the rectifier circuit via the third through hole (16) and the second through hole (15) in sequence.

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