Metamaterial cladding rectification antenna based on shunt-feed network and radio frequency energy collection system

Abstract

The invention relates to a shunt-feed network-based metamaterial cladding rectifier antenna and a radio frequency energy collection system. The metamaterial cladding rectifying antenna based on the shunt-feed network comprises a dielectric substrate, a ground plane, a radiation patch and a feed port. The split-ring resonators are arranged in a 2 * 2 array, and the arrangement mode can achieve the purpose of efficient integration. The metamaterial cladding structure formed by the split-ring resonators can reduce the coupling effect between the patch array elements, and the miniaturization of the antenna is realized. Moreover, through the arrangement of the split-ring resonators, the gain of the antenna and the internal current of the patch array elements can be improved, and the collection of electromagnetic energy in the space is facilitated. Finally, feed is realized through the shunt-feed network and the feed port, and the structure is simplified. The radio frequency energy collection system can efficiently convert radio frequency energy into direct current, further improves the energy conversion efficiency under the action of the matching circuit, the rectification circuit and the filter circuit, and can meet the energy supply demand of the low-power-consumption power sensor.

Description

Technical Field

[0001] The present invention relates to the technical field of radio frequency energy collection, and in particular to a metamaterial clad rectenna based on a parallel-feed network and a radio frequency energy collection system. Background Art

[0002] Power sensors are measuring devices that can convert electrical energy parameters such as current and voltage in power systems into standard signal outputs. Power sensors play a vital role in the operation and monitoring of power systems. And with the continuous development of smart grids, power sensors are also of great significance in the construction of smart grids.

[0003] However, the development of power sensors is currently limited by energy supply issues. Chemical batteries and wired cables are two traditional energy supply methods. Sensors powered by batteries have a short working life, and batteries need to be replaced regularly, which is difficult to replace at high potentials. The operation and maintenance costs are high. Cable energy transmission is limited by environmental factors such as terrain, so its application range is limited. If on-site energy replenishment can be achieved, the power supply problem can be well solved. Therefore, RF energy harvesting technology has continued to become a hot topic for research by experts and scholars. Its advantages are that it is not affected by environmental factors, the energy source is relatively stable, the space loss is small, and the transmission power is flexible. It is a self-powered technology that solves the energy supply problem of low-power sensors.

[0004] However, most existing RF energy harvesting antennas are large in size, not conducive to on-site installation, have low gain, and cannot effectively receive RF energy in the surrounding environment. In addition, the RF rectification circuit has low conversion efficiency and cannot ensure the stable operation of low-power power sensors. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a metamaterial clad rectenna and a radio frequency energy collection system based on a parallel-feed network to solve the above technical problems.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: a metamaterial clad rectenna based on a parallel feed network, comprising: a dielectric substrate, a ground plane, a radiating patch and a feeding port; one side of the dielectric substrate is connected to the ground plane, and at least one radiating patch is connected to the other side of the dielectric substrate; each of the radiating patches comprises a parallel feed network and at least two patch array elements, and each patch array element is respectively connected to the parallel feed network; the patch array element is connected to an open resonant ring arranged in a 2×2 array; the output end of the parallel feed network of each radiating patch is connected to the feeding port.

[0007] The beneficial effects of the present invention are as follows: the open resonant rings are arranged in a 2×2 array, and this arrangement can achieve the purpose of efficient integration. The metamaterial cladding structure formed by the open resonant rings can reduce the coupling between the patch array elements and realize the miniaturization of the antenna. In addition, by setting the open resonant rings, the gain of the antenna and the internal current of the patch array elements can also be improved, which is conducive to the collection of electromagnetic energy in space. Finally, feeding is achieved through the parallel feeding network and the feeding port, and the structure is simplified.

[0008] Based on the above technical solution, the present invention can also be improved as follows.

[0009] Furthermore, the dielectric substrate is provided with two layers, and the two layers of the dielectric substrate are overlapped and connected together.

[0010] The beneficial effect of adopting the above further solution is that providing two layers of dielectric substrates can reduce the influence of the metamaterial structure on the patch array elements.

[0011] Furthermore, the dielectric substrate is a FR-4 epoxy glass cloth laminate with a thickness of 0.8 mm and a relative dielectric constant of 4.4.

[0012] The beneficial effect of adopting the above further solution is that the dielectric substrate is made of FR-4 material, which has the characteristics of low cost and high use value.

[0013] Furthermore, each of the patch array elements is a rectangular structure, and all the patch array elements are distributed on the dielectric substrate in equal rows and columns.

[0014] The beneficial effect of adopting the above further solution is that the distribution of patch array elements in equal rows and columns can make the antenna closer to a square patch antenna, thereby achieving higher radiation efficiency.

[0015] Furthermore, the parallel-feed network includes a two-way power divider and a microstrip line, and a port of the two-way power divider is connected to the patch array element, an adjacent two-way power divider or the feeding port through the microstrip line.

[0016] Furthermore, the open resonant ring includes a first open metal ring and a second open metal ring, the first open metal ring and the second open metal ring are both regular hexagonal structures, the first open metal ring is surrounded by the second open metal ring, and the opening direction of the first open metal ring is opposite to the opening direction of the second open metal ring.

[0017] Furthermore, the inscribed circle diameter of the first open metal ring is 1.8 mm, the inscribed circle diameter of the second open metal ring is 4 mm, the thickness of the first open metal ring and the second open metal ring are both 0.3 mm, and the opening lengths of the first open metal ring and the second open metal ring are both 0.6 mm.

[0018] Furthermore, each of the patch array elements, the ground plane and the open resonant ring is a copper sheet with a thickness of 0.035 mm.

[0019] In order to solve the above technical problems, the present invention also proposes a radio frequency energy harvesting system, comprising the metamaterial clad rectenna based on the parallel feed network as described above, and a matching circuit, a rectifier circuit and a filter circuit connected in sequence to the metamaterial clad rectenna based on the parallel feed network.

[0020] The beneficial effects of the present invention are as follows: the RF energy collection system can efficiently convert RF energy into DC, and under the action of matching circuits, rectification circuits and filtering circuits, the energy conversion efficiency is further improved, which can meet the energy supply requirements for low-power power sensors.

[0021] Furthermore, the matching circuit is a single-branch impedance matching circuit, the rectifying circuit is a double voltage rectifying circuit, and the filtering circuit is a microstrip line ladder impedance low-pass filtering circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a metamaterial cladding rectenna based on a parallel-feed network of the present invention;

[0023] Figure 2 It is a schematic diagram of the metamaterial-clad rectenna open resonant ring based on the parallel-feed network of the present invention before cladding;

[0024] Figure 3 This is a schematic diagram of the arrangement of a 2×2 array of split resonant rings;

[0025] Figure 4 This is a schematic diagram of the arrangement of a 1×2 array of split resonant rings;

[0026] Figure 5 Schematic diagram of uniform arrangement of split resonant rings;

[0027] Figure 6 This is a comparison chart of the return loss of three arrangements of split resonant rings;

[0028] Figure 7 The gain pattern of the metamaterial-clad rectenna based on the parallel-feed network of the present invention;

[0029] Figure 8 This is a circuit diagram of the radio frequency energy collection system of the present invention;

[0030] Fig. 9 It is a schematic diagram of a microstrip line stepped impedance low-pass filter circuit of a radio frequency energy harvesting system of the present invention;

[0031] Fig.10is an output voltage diagram of the radio frequency energy harvesting system of the present invention;

[0032] Fig.11 This is a diagram of the rectification efficiency of the radio frequency energy harvesting system of the present invention.

[0033] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0034] 1. Dielectric substrate; 2. Ground plane; 3. Feed port; 4. Patch array element; 5. Two-way power divider; 6. Microstrip line; 7. First open metal ring; 8. Second open metal ring; 9. Matching circuit; 10. Rectification circuit; 11. Filter circuit. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] Embodiment 1

[0037] like Figure 1 As shown, this embodiment provides a metamaterial clad rectenna based on a parallel feed network, comprising: a dielectric substrate 1, a ground plane 2, a radiating patch and a feeding port 3; one side of the dielectric substrate 1 is connected to the ground plane 2, and at least one radiating patch is connected to the other side of the dielectric substrate 1; each of the radiating patches comprises a parallel feed network and at least two patch array elements 4, and each patch array element 4 is respectively connected to the parallel feed network; the patch array element 4 is connected to an open resonant ring (SRR) arranged in a 2×2 array; the output end of the parallel feed network of each of the radiating patches is connected to the feeding port 3.

[0038] The open resonant rings are arranged in a 2×2 array, which can achieve the purpose of efficient integration. The metamaterial cladding structure formed by the open resonant ring can reduce the coupling between the patch array elements 4 and realize the miniaturization of the antenna. In addition, by setting the open resonant ring, the gain of the antenna and the internal current of the patch array element 4 can also be improved, which is conducive to the collection of electromagnetic energy in space. Finally, feeding is achieved through the parallel feeding network and the feeding port 3, which simplifies the structure.

[0039] Optionally, in an embodiment, the dielectric substrate 1 is provided with two layers, and the two layers of the dielectric substrate 1 are overlapped and connected together.

[0040] The two layers of dielectric substrates 1 are made of the same material, shape, size, etc. The two layers of dielectric substrates 1 are both 0.8 mm thick, 114.6 mm long, and 123.6 mm wide. The two layers of dielectric substrates 1 can reduce the influence of the metamaterial structure on the patch array element 4.

[0041] Optionally, in the embodiment, the dielectric substrate 1 is a FR-4 epoxy glass cloth laminate with a thickness of 0.8 mm and a relative dielectric constant of 4.4. The dielectric substrate 1 is made of FR-4 material, which has the characteristics of low cost and high use value.

[0042] Optionally, in an embodiment, each of the patch array elements 4 is a rectangular structure, and all the patch array elements 4 are distributed in equal rows and columns on the dielectric substrate 1. The length of the patch array element 4 is set to 10.8 mm, and the width is set to 15.8 mm. The distribution of the patch array elements 4 in equal rows and columns can make the antenna closer to a square patch antenna, thereby achieving higher radiation efficiency.

[0043] Optionally, in an embodiment, the parallel feed network includes a bisection power divider 5 and a microstrip line 6, and a port of the bisection power divider 5 is connected to the patch array element 4, an adjacent bisection power divider 5 or the feed port 3 through the microstrip line 6. The position of the feed port 3 is reasonably set. For example, when two parallel feed networks are included, the feed port 3 can be set at the center of the dielectric substrate 1, and the two parallel feed networks are distributed on both sides of the feed port 3. By reasonably setting the position of the feed port 3, the loss of the microstrip line 6 is reduced.

[0044] Optionally, in an embodiment, the open resonant ring includes a first open metal ring 7 and a second open metal ring 8, the first open metal ring 7 and the second open metal ring 8 are both regular hexagonal structures, the first open metal ring 7 is enclosed in the second open metal ring 8, and the opening direction of the first open metal ring 7 is opposite to the opening direction of the second open metal ring 8.

[0045] Optionally, in an embodiment, the diameter of the inscribed circle of the first open metal ring 7 is 1.8 mm, the diameter of the inscribed circle of the second open metal ring 8 is 4 mm, the thickness of the first open metal ring 7 and the second open metal ring 8 are both 0.3 mm, and the opening lengths of the first open metal ring 7 and the second open metal ring 8 are both 0.6 mm.

[0046] Optionally, in an embodiment, each of the patch array element 4 , the ground plane 2 and the open resonant ring is a copper sheet with a thickness of 0.035 mm.

[0047] The following is described in conjunction with specific embodiments:

[0048] like Figure 2As shown, two radiating patches are provided, each of which includes a parallel feed network and a 2×4 patch array element 4. The two radiating patches are arranged in parallel, and the patch array elements 4 in the two radiating patches are arranged together into a 4×4 array. For each parallel feed network, 7 bisection power dividers 5 are included to connect the patch array elements 4 and finally converge to the feed port 3. The feed port 3 is arranged between the two parallel feed networks, that is, at the center of the dielectric substrate 1, to simplify the structure. At present, the application of the intelligent Internet is becoming more and more extensive, and the number of devices using the 5.8GHz frequency band is gradually increasing. Therefore, the operating frequency of the antenna is optimized and adjusted to 5.8GHz through electromagnetic simulation software.

[0049] like Figures 3 to 5 As shown, three structures of 2×2SRR, 1×2SRR and SRR uniform distribution are selected for coating respectively. Through research, it can be seen that the metamaterial coating structure is very important for the energy collection performance of the antenna, and different coating structures have different degrees of influence.

[0050] like Figure 6 As shown in the figure, the return loss of three metamaterial cladding structures, 2×2SRR, 1×2SRR and SRR uniform distribution, is obtained through Ansoft HFSS electromagnetic simulation results. When the cladding structure is 2×2SRR and 1×2SRR, it can be seen that the resonance point of the antenna is still at 5.8GHz, and the return loss values ​​here are -23.08dB and -18.82dB respectively, and the bandwidth of the 2×2SRR cladding structure less than -10dB is significantly larger than that of 1×2SRR, which is 990MHz. When the cladding structure is SRR uniform distribution, it can be seen that the return loss curve is significantly shifted to the right near 5.8GHz, and the return loss value at 5.8GHz is significantly larger than the first two cladding structures. And refer to Figure 7 It can be seen that the maximum gain of the 2×2SRR cladding structure can reach 13.32dB i. Therefore, the 2×2SRR has the best effect when used as a cladding structure and can achieve the purpose of efficient integration.

[0051] Embodiment 2

[0052] like Figure 8 As shown, this embodiment provides a radio frequency energy harvesting system, including the metamaterial clad rectenna based on the parallel feed network described in Example 1, and a matching circuit 9, a rectifier circuit 10 and a filter circuit 11 connected in sequence to the metamaterial clad rectenna based on the parallel feed network.

[0053] Optionally, in an embodiment, the matching circuit 9 is a single-branch impedance matching circuit, the rectifier circuit 10 is a double voltage rectifier circuit, and the filter circuit 11 is a microstrip line 6-step impedance low-pass filter circuit.

[0054] The single-branch matching circuit 9 has a smaller size than the double-branch matching circuit. The single-branch matching circuit 9 includes two sections of microstrip lines 6 , has lower loss, and can achieve good impedance matching between the antenna and the subsequent rectifier circuit 10 .

[0055] The rectifier circuit 10 adopts a double voltage rectifier circuit structure, and its circuit structure includes two identical capacitors, a diode and three microstrip lines 6. Half-wave rectifier circuit, double voltage rectifier circuit and full-bridge rectifier circuit are three common rectifier circuits 10. Compared with the full-bridge rectifier circuit, under the same input power condition, the output voltage of the double voltage rectifier circuit is higher, because the diode in the full-bridge rectifier circuit consumes more energy. And the rectification efficiency of the double voltage rectifier circuit is higher than the conversion efficiency of the other two rectifier circuits 10 under different input powers.

[0056] The filter circuit 11 adopts a microstrip line ladder impedance low-pass filter circuit, including five sections of microstrip lines 6 converted from capacitors and inductors and a section of microstrip line 6 connected to the rectifier circuit 10. It is introduced at the rear end of the rectifier circuit 10, and the nonlinear high-order harmonics generated by the diode are effectively reduced, and the circuit rectification conversion efficiency is greatly improved. Fig. 9 This is a circuit diagram of a microstrip line 6-step impedance low-pass filter, which is a low-pass filter composed of prototype components, including capacitor C 1 , C 3 and C 5 , and the inductor L 2 and L 4 .

[0057] like Fig.10 and Fig.11 As shown, the analysis of the output voltage and rectification efficiency shows that within the input power range greater than 28dBm, a stable output voltage of 6.5V can be obtained, and the maximum efficiency is achieved at 16.7dBm, which is 56.14%, and can ultimately meet the energy supply requirements for low-power power sensors.

[0058] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0062] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A metamaterial cladding rectenna based on a parallel-feed network, characterized in that: include: A dielectric substrate (1), a ground plane (2), a radiation patch and a feeding port (3); One side of the dielectric substrate (1) is connected to the ground plane (2), and the other side of the dielectric substrate (1) is connected to at least one radiating patch; each of the radiating patches comprises a parallel feed network and at least two patch array elements (4), and each patch array element (4) is respectively connected to the parallel feed network; the patch array elements (4) are connected to open resonant rings arranged in a 2×2 array; and the output end of the parallel feed network of each of the radiating patches is connected to the feeding port (3).

2. According to the metamaterial cladding rectenna based on the parallel-feed network of claim 1, it is characterized in that: The dielectric substrate (1) is provided with two layers, and the two layers of the dielectric substrate (1) are superimposed and connected together.

3. The metamaterial cladding rectenna based on the parallel-feed network according to claim 1, characterized in that: The dielectric substrate (1) is a FR-4 epoxy glass cloth laminate with a thickness of 0.8 mm and a relative dielectric constant of 4.

4.

4. According to the metamaterial cladding rectenna based on the parallel-feed network of claim 1, it is characterized in that: Each of the patch array elements (4) is a rectangular structure, and all the patch array elements (4) are distributed on the dielectric substrate (1) in equal rows and columns.

5. The metamaterial cladding rectenna based on a parallel-feed network according to claim 1, characterized in that: The parallel feed network comprises a halved power divider (5) and a microstrip line (6), and a port of the halved power divider (5) is connected to the patch array element (4), an adjacent halved power divider (5) or the feeding port (3) via the microstrip line (6).

6. The metamaterial cladding rectenna based on a parallel-feed network according to claim 1, characterized in that: The open resonant ring comprises a first open metal ring (7) and a second open metal ring (8); the first open metal ring (7) and the second open metal ring (8) are both regular hexagonal structures; the first open metal ring (7) is enclosed in the second open metal ring (8); the opening direction of the first open metal ring (7) is opposite to the opening direction of the second open metal ring (8).

7. The metamaterial cladding rectenna based on a parallel-feed network according to claim 6, characterized in that: The inscribed circle diameter of the first open metal ring (7) is 1.8 mm, the inscribed circle diameter of the second open metal ring (8) is 4 mm, the thickness of the first open metal ring (7) and the second open metal ring (8) are both 0.3 mm, and the opening lengths of the first open metal ring (7) and the second open metal ring (8) are both 0.6 mm.

8. The metamaterial cladding rectenna based on a parallel-feed network according to claim 1, characterized in that: Each of the patch array elements (4), the ground plane (2) and the open resonant ring are copper sheets with a thickness of 0.035 mm.

9. A radio frequency energy harvesting system, characterized in that: It comprises the metamaterial clad rectenna based on a parallel-feed network as claimed in any one of claims 1 to 8, and a matching circuit (9), a rectifier circuit (10) and a filter circuit (11) connected in sequence to the metamaterial clad rectenna based on a parallel-feed network.

10. The radio frequency energy harvesting system according to claim 9, characterized in that: The matching circuit (9) is a single-branch impedance matching circuit, the rectification circuit (10) is a double voltage rectification circuit, and the filtering circuit (11) is a microstrip line ladder impedance low-pass filtering circuit.

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