Ultra-wideband dual-circularly-polarized rectifying antenna

Abstract

The invention discloses an ultra-wide-band dual-circular-polarization rectifying antenna. The ultra-wide-band dual-circular-polarization rectifying antenna is composed of a receiving antenna and a rectifying circuit. According to the receiving antenna, the ultra-wideband dual-circular polarization is realized through dual-port feeding and the ultra-wideband characteristic of the monopole antenna. The rectifying circuit adopts a two-stage cascade voltage doubling rectifying structure, so that the sensitivity of the impedance of the rectifying circuit to the working frequency is lower, and a high-efficiency rectifying effect in an ultra-wideband frequency band is realized. And the two are connected together through an SMA joint. The receiving antenna is used for receiving radio frequency energy in the environment, the energy is transmitted to the rectifying circuit through the output port, the rectifying circuit rectifies the radio frequency energy and converts the radio frequency energy into direct current energy, and direct current voltage is output on a load of the rectifying circuit. Therefore, higher energy conversion efficiency is realized in a wide frequency range.

Description

Technical Field

[0001] The present application relates to a microwave rectenna, and in particular to an ultra-wideband dual circularly polarized rectenna. Background Art

[0002] With the continuous development of society, the limited reserves of fossil energy used in production and daily life will eventually lead to energy shortages. Therefore, the development and utilization of renewable energy sources with minimal environmental impact has become a research priority for scientific research institutions worldwide. In recent years, wireless power transfer (WPT) technology has attracted increasing attention from academia and industry. This energy transmission method plays a key role when traditional wired energy transmission is inconvenient or impossible. It not only expands the use range of certain electronic devices but also enables the implementation of certain device applications, making it a promising technology. In recent years, battery-powered electronic devices, including various wireless sensors, have achieved tremendous success. However, their dependence on batteries remains a drawback. This is mainly due to the limited battery life and the need for rapid charging for continuous operation. The need for wired charging of traditional batteries limits their application. However, wireless power transfer meets the needs of economic and social development. It can resolve many of the contradictions caused by wired transmission and significantly change existing production and lifestyles, making them more convenient and efficient. Compared to traditional contact-based power supply methods, WPT does not require batteries for energy storage, nor does it require traditional wires or sockets. Instead, it uses radio frequency (RF) energy to transmit energy from the transmitter to the receiver. The receiver and transmitter do not require physical contact, and transmission is not limited by distance or location. This flexibility makes it an ideal solution for charging various electronic devices that are difficult to directly power manually. Therefore, with the rapid development of domestic semiconductor and microwave integrated circuit technologies, microwave energy transmission technology is no longer limited to the development and research of space solar energy, but has also begun to be widely used in all aspects of production and life. For example, microwaves can be used to drive drones, operate wireless radio frequency identification systems, and enable the normal operation of miniaturized wearable electronic devices.

[0003] WPT can be categorized into near-field and far-field wireless energy transmission based on the length of the transmission wavelength. Near-field wireless energy transmission is divided into electromagnetic induction, resonant coupling, and electric field coupling. Far-field wireless energy transmission is divided into laser transmission and microwave power transfer (MPT). Near-field wireless energy transmission typically has an effective range of a few centimeters to meters, and its operating frequency typically ranges from several hundred kHz to tens of MHz. Far-field wireless energy transfer technology can achieve transmission distances in the kilometer range, operating at frequencies in the gigahertz range. It exhibits strong directionality and energy concentration, but its transmission efficiency needs improvement. Far-field wireless energy transmission is divided into laser transmission and microwave power transfer (MPT). Laser energy transmission technology has strict requirements for the operating environment and requires an obstacle-free transmission path, resulting in limited practical application. A microwave power transmission system primarily consists of three components: microwave energy transmission, spatial propagation, wireless energy reception, and rectification and conversion. DC energy is converted into microwave energy through a microwave energy generator, and then transmitted to the transmission space through a transmitting antenna. The rectenna acts as a receiving antenna to receive the microwave energy in the space. The microwave energy is then converted into DC energy in the rectenna to power the load.

[0004] One of the key performance indicators of wireless energy transfer systems is transmission efficiency. Therefore, the receiving rectenna is a crucial component of an MPT system, and its energy conversion efficiency is the most important parameter for evaluating its performance. In practical applications, the energy conversion efficiency of the rectifier circuit is low due to the limited conduction voltage and high-order harmonics of the rectifier diode. Furthermore, for the receiving antenna, environmental electromagnetic signals often span multiple frequency bands and are subject to polarization reversal and mismatch during propagation, which also reduces the energy conversion efficiency of the rectenna. To effectively receive signals across multiple frequency bands and polarizations, broadband circularly polarized rectennas have become a hot topic among researchers. Broadband circularly polarized receiving antennas can reduce signal fading caused by multipath propagation, improving signal reliability and stability. They also avoid polarization loss caused by mismatches between the signal polarization and the transmitting antenna. Compared to linearly polarized receiving antennas, circularly polarized receiving antennas are better able to receive signals from different directions, thus offering greater compatibility. In practical applications, different devices and systems often use different polarization schemes and operate at different frequencies, such as GSM1800 (1.8 GHz), LTE 2.1 GHz, and WLAN / Wi-Fi (2.45 GHz and 5.8 GHz). Ultra-wideband circularly polarized receiving antennas can adapt to this diversity. Therefore, researching a high-efficiency, ultra-wideband circularly polarized rectenna is of great practical value.

[0005] To enable rectennas to operate across different frequency bands, researchers at home and abroad have proposed various methods for their design. In the paper "ZXDu, SFBo, YFCao, JHOu, and XYZhang, "Broadband circularly polarized rectenna with wide dynamic-power-range for efficient wireless power transfer," IEEE Access, vol. 8, pp. 80561–80571, 2020," researchers proposed a broadband circularly polarized rectenna based on an impedance compression network. This network suppresses the diode's second harmonic, meeting the requirements of broadband and circular polarization and achieving high energy conversion efficiency across a wide frequency band. In the paper "C. Song, Y. Huang, J. Zhou, J. Zhang, S. Yuan, and P. Carter, "A high-efficiency broadband rectenna for ambient wireless energy harvesting," IEEE Trans. Antennas Propag., vol. 63, no. 8, pp. 3486-3495, May 2015," researchers designed a cross-dipole rectenna with harmonic suppression to suppress the diode's second harmonic. They also incorporated two matching networks into the rectifier circuit to achieve broadband impedance matching, extending the rectenna's operating bandwidth and achieving broadband high efficiency. However, both approaches share a common drawback: the rectenna's feed network is complex, the circuit area is large, and the production cost is high. In the paper "P. Lu, C. Song, and KM Huang, "A two-port multipolarization rectenna with orthogonal hybrid coupler for simultaneous wireless information and power transfer (SWIPT)," IEEE Trans. Antennas Propag., vol. 68, no. 10, pp. 6893-6905, Oct. 2020," researchers designed a rectenna with dual circular polarization, achieving this through dual-port feeding using an orthogonal coupler. However, this rectenna suffers from narrow bandwidth, low energy conversion efficiency, and complex fabrication. Summary of the Invention

[0006] The purpose of this application is to provide an ultra-wideband dual circularly polarized rectenna to address at least one of the problems of the prior art rectennas, namely, narrow bandwidth, low energy conversion efficiency, complex processing, and large circuit area.

[0007] The present invention provides an ultra-wideband dual circularly polarized rectenna, comprising:

[0008] A receiving antenna and a rectifier circuit, wherein the receiving antenna and the rectifier circuit are connected together via an SMA connector;

[0009] The receiving antenna includes a first dielectric substrate, a first metal floor, a main radiation patch and a first microstrip structure; the first metal floor, the first microstrip structure and the main radiation patch are all printed on the upper surface of the first dielectric substrate;

[0010] The rectifier circuit includes a second microstrip structure, a second dielectric substrate, and a second metal floor. The second microstrip structure is printed on the upper surface of the second dielectric substrate, and the second metal floor is printed on the lower surface of the second dielectric substrate.

[0011] Optionally, the first metal floor is a square ring-shaped metal floor, and the square ring-shaped metal floor is formed by opening a square hole in the center of the square metal floor;

[0012] Two rectangular grooves are etched on two adjacent sides of the square annular metal floor, and two rectangular gaps are etched on the other two sides of the square annular metal floor. The two rectangular gaps form a first port and a second port respectively.

[0013] Optionally, the main body of the primary radiation patch is composed of a square patch with two cut corners;

[0014] The cut corners are formed by cutting off two isosceles triangles from two opposite corners of the square patch;

[0015] Two U-shaped branches are provided at one of the cut corners.

[0016] Optionally, the first microstrip structure is composed of a first microstrip main line, a second microstrip main line, and a third microstrip main line, wherein one end of the first microstrip main line and the second microstrip main line are respectively connected to the main radiation patch, and the other ends of the first microstrip main line and the second microstrip main line are respectively connected to the first port and the second port;

[0017] The third microstrip main line is arranged at the center of another cut angle opposite to the cut angle where the U-shaped branch of the main radiation patch is located, one end of the third microstrip main line is connected to the main radiation patch, and the other end of the third microstrip main line is connected to the first metal floor.

[0018] Optionally, the rectifier circuit further includes a T-type broadband matching network and a two-stage Cascade voltage-doubler rectifier structure;

[0019] The second microstrip structure is composed of a T-type broadband matching network and a microstrip line in a two-stage Cascade voltage doubler rectifier structure;

[0020] The T-type broadband matching network includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, and a fifth microstrip line;

[0021] in,

[0022] The first microstrip line is perpendicular to the second microstrip line and the third microstrip line, and the fourth microstrip line is parallel to the fifth microstrip line;

[0023] The first microstrip line is located on the left side of the second microstrip line and the third microstrip line;

[0024] The second microstrip line is perpendicular to the fourth microstrip line, and the second microstrip line is located on the left side of the fourth microstrip line;

[0025] The third microstrip line is perpendicular to the fifth microstrip line, and the third microstrip line is located on the left side of the fifth microstrip line.

[0026] Optionally, the rectifier circuit further includes a patch component, and the patch component includes a first diode, a second diode, a third diode, and a fourth diode;

[0027] The first diode is vertically connected to the second diode, and the second diode is located on the left side of the first diode;

[0028] The third diode is vertically connected to the fourth diode, and the fourth diode is located on the left side of the third diode.

[0029] Optionally, the patch component further includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a first resistor;

[0030] The two-stage Cascade voltage multiplier rectifier structure further includes a sixth microstrip line, a seventh microstrip line, an eighth microstrip line, a ninth microstrip line, a tenth microstrip line, an eleventh microstrip line, a twelfth microstrip line, a thirteenth microstrip line, a fourteenth microstrip line, a fifteenth microstrip line, a sixteenth microstrip line, a seventeenth microstrip line, an eighteenth microstrip line, and a nineteenth microstrip line;

[0031] The first capacitor is located between the fourth microstrip line and the sixth microstrip line, and the fourth microstrip line is located on the left side of the sixth microstrip line;

[0032] The second capacitor is located between the fifth microstrip line and the seventh microstrip line, and the fifth microstrip line is located on the left side of the seventh microstrip line;

[0033] The first diode is located between the sixth microstrip line and the eighth microstrip line, the sixth microstrip line is parallel to the eighth microstrip line, and the eighth microstrip line is located on the right side of the sixth microstrip line;

[0034] The second diode is located between the sixth microstrip line and the ninth microstrip line, the sixth microstrip line is parallel to the ninth microstrip line, and the ninth microstrip line is located on the right side of the sixth microstrip line;

[0035] The third diode is located between the seventh microstrip line and the tenth microstrip line, the seventh microstrip line is parallel to the tenth microstrip line, and the tenth microstrip line is located on the right side of the seventh microstrip line;

[0036] The fourth diode is located between the seventh microstrip line and the eleventh microstrip line, the seventh microstrip line is parallel to the eleventh microstrip line, and the eleventh microstrip line is located on the right side of the seventh microstrip line;

[0037] The eighth microstrip line, the ninth microstrip line, the tenth microstrip line, and the eleventh microstrip line are parallel. The twelfth microstrip line is perpendicular to the eighth microstrip line and is located on the right side of the eighth microstrip line.

[0038] The thirteenth microstrip line is perpendicular to the ninth microstrip line and the tenth microstrip line, and the thirteenth microstrip line is located on the right side of the ninth microstrip line and the tenth microstrip line;

[0039] The fourteenth microstrip line (14) is perpendicular to the eleventh microstrip line (11), and the eleventh microstrip line is located on the left side of the fourteenth microstrip line.

[0040] Optionally, the third capacitor is located between the twelfth microstrip line and the thirteenth microstrip line, and an end of the twelfth microstrip line is connected to the second metal ground through a metal via;

[0041] The fourth capacitor is located between the thirteenth microstrip line and the fourteenth microstrip line. The fifth capacitor is located between the fourteenth microstrip line and the fifteenth microstrip line, and an end of the fifteenth microstrip line is connected to the second metal ground through a metal via;

[0042] The sixteenth microstrip line is perpendicular to the twelfth microstrip line and the seventeenth microstrip line, and the sixteenth microstrip line is located on the right side of the twelfth microstrip line;

[0043] The nineteenth microstrip line is perpendicular to the fourteenth microstrip line and the eighteenth microstrip line, and the nineteenth microstrip line is located on the right side of the fourteenth microstrip line;

[0044] The first resistor is located between the seventeenth microstrip line and the eighteenth microstrip line.

[0045] Optionally, the ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the axial ratio bandwidth of the ultra-wideband dual circularly polarized rectenna is 1.35-3.37 GHz.

[0046] Optionally, the ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the operating bandwidth of the ultra-wideband dual circularly polarized rectenna is 1.35-3.37 GHz.

[0047] Optionally, the ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the operating input power of the ultra-wideband dual circularly polarized rectenna is 18 dBm.

[0048] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows: the receiving antenna of the above-mentioned scheme realizes ultra-wideband dual circular polarization through dual-port feeding and the ultra-wideband characteristics of the monopole antenna. The rectifier circuit uses a two-stage cascade voltage-doubling rectifier structure, which makes the impedance of the rectifier circuit less sensitive to the operating frequency, and realizes a high-efficiency rectification effect within the ultra-wideband band. The two are connected together through an SMA connector. The broadband dual circular polarization receiving antenna is used to receive radio frequency energy in the environment, and transmit the energy to the rectifier circuit through the output port. The rectifier circuit rectifies the radio frequency energy, converts the radio frequency energy into DC energy, and outputs a DC voltage on the rectifier circuit load. Thus, higher energy conversion efficiency is achieved within a wide frequency range. In addition, the technical solution of the present invention proposes a two-stage cascade voltage-doubling rectifier structure to expand the operating frequency range of the rectifier circuit, and only a simple T-type broadband matching network is required to achieve matching between the rectifier circuit and the input source. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a receiving antenna provided in an embodiment of the present application;

[0050] Figure 2 A schematic diagram of a rectifier circuit provided in an embodiment of the present application;

[0051] Figure 3 A schematic diagram of simulation and testing of the axial ratio of a receiving antenna provided in an embodiment of the present application;

[0052] Figure 4 A directional pattern of a receiving antenna provided in an embodiment of the present application tested in a microwave darkroom;

[0053] Figure 5 A schematic diagram of return loss simulation and test results of a rectifier circuit provided in an embodiment of the present application;

[0054] Figure 6 A schematic diagram of the energy conversion efficiency simulation and test results of a rectenna provided in an embodiment of the present application; DETAILED DESCRIPTION

[0055] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0056] It should be noted that when an element is referred to as being “fixed on” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0057] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0058] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0059] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] like Figure 1As shown, an embodiment of the present invention provides an ultra-wideband dual circularly polarized rectenna, comprising a receiving antenna comprising a square first dielectric substrate with a thickness h of 0.762 mm and a width W1 of 60 mm. Preferably, the first dielectric substrate is made of FR4, having a dielectric constant εr of 4.4 and a loss tangent tanδ of 0.02. The receiving antenna also comprises a first metal floor, a first microstrip structure, and a main radiating patch, wherein the first metal floor, the first microstrip structure, and the main radiating patch are all printed on the top surface of the first dielectric substrate. The first metal floor of the receiving antenna is a square ring-shaped metal floor of the same size as the top surface of the first dielectric substrate, formed by a square hole in the center of the square metal floor, with a side length of W2 = 40 mm. Two rectangular grooves are etched on two adjacent sides of the square ring-shaped metal floor, wherein the rectangular grooves have a length Ux = 9.4 mm and a width Uy = 5 mm. Two rectangular slots are etched on the other two sides of the square ring-shaped metal floor. The slots have a width of g = 0.5 mm and a length of W1 - W2 = 20 mm. The two slots form a first port and a second port, respectively. The first port and the second port form a coplanar waveguide (CPW) port.

[0061] Please continue to see Figure 1 The main body of the main radiation patch provided in this embodiment is composed of a square patch with two cut corners; the cut corners are formed by cutting off two isosceles triangles from two opposite corners of the square patch; and two U-shaped branches are provided at one of the cut corners. As one of the preferred embodiments, the main radiation patch is a square radiation patch with a side length of W4=26mm, and the diagonal angle of the square radiation patch in the -45° direction is cut, and the size of the cut corner is Cl=8.5mm. When port 1 is used for feeding, port 2 is connected to a 50Ω load, and the phase c of the horizontal electric field of the receiving antenna leads the phase of the vertical electric field by 90°, thereby achieving the characteristic of left-hand circular polarization. When port 2 is used for feeding, port 1 is connected to a 50Ω load, and the phase of the horizontal electric field of the antenna lags the phase of the vertical electric field by 90°, thereby achieving the characteristic of right-hand circular polarization. The embodiment of the present invention further adds two U-shaped branches at the cut corner position where the current density of the square radiation patch is the largest, which can further widen the working bandwidth of the antenna. The U-shaped branch has a length of Ux = 9.4 mm and a width of Uy = 5 mm. Two rectangular grooves are etched in the first metal floor to reduce coupling between the U-shaped branch and the metal floor, achieving a better matching effect. The two rectangular grooves have the same dimensions as the U-shaped branch.

[0062] Please continue to see Figure 1The first microstrip structure of the embodiment of the present invention is specifically composed of a first microstrip main line, a second microstrip main line and a third microstrip main line, wherein one end of the first microstrip main line and the second microstrip main line are respectively connected to the main radiation patch, and the other ends of the first microstrip main line and the second microstrip main line are respectively connected to the first port and the second port; the third microstrip main line is arranged at the center of another cut angle opposite to the cut angle where the U-shaped branch of the main radiation patch is located, one end of the third microstrip main line is connected to the main radiation patch, and the other end of the third microstrip main line is connected to the first metal floor, wherein the line width of the third microstrip main line is W5=1.3mm, and the isolation of the two feeding ports of the receiving antenna can be improved through the third microstrip main line.

[0063] like Figure 2 As shown, an embodiment of the present invention provides a broadband, miniaturized, and highly efficient rectifier circuit, primarily composed of a T-type broadband matching network I and a two-stage Cascade voltage-doubler rectifier structure II, connected sequentially from left to right. The second microstrip structure comprises the T-type broadband matching network I and the microstrip lines within the two-stage Cascade voltage-doubler rectifier structure II. The design steps of the present invention are to first design the two-stage Cascade voltage-doubler rectifier structure II, and finally design the T-type broadband matching network I. The rectifier circuit in this embodiment has an operating bandwidth of 0.1 GHz to 4 GHz, and a signal source port impedance of 50 Ω. As a preferred embodiment, the rectifier circuit further includes patch components, comprising a first diode 22, a second diode 23, a third diode 24, and a fourth diode 25. The first diode 22 is vertically connected to the second diode 23, with the second diode 23 located to the left of the first diode 22. The third diode 24 is vertically connected to the fourth diode 25, with the fourth diode 25 located to the left of the third diode 24. As a preferred embodiment, the patch component further includes a first capacitor 20 , a second capacitor 21 , a third capacitor 26 , a fourth capacitor 27 , a fifth capacitor 28 and a first resistor 29 .

[0064] As one of the preferred embodiments, the two-stage Cascade voltage doubler rectifier structure II is composed of a first capacitor 20 for blocking DC and passing AC, a second capacitor 21, a rectifier part, a harmonic suppression structure and a load end.

[0065] As one of the preferred embodiments, the rectifier portion of the two-stage Cascade voltage multiplier rectifier structure II consists of four diodes and six microstrip lines. The four diodes are a first diode 22, a second diode 23, a third diode 24, and a fourth diode 25. The six microstrip lines are a sixth microstrip line 6, a seventh microstrip line 7, an eighth microstrip line 8, a ninth microstrip line 9, a tenth microstrip line 10, and an eleventh microstrip line 11. The anode of the first diode 22 is connected to the eighth microstrip line 8, and the cathode is connected to the sixth microstrip line 6. The anode of the second diode 23 is connected to the sixth microstrip line 6, and the cathode is connected to the ninth microstrip line 9. The anode of the third diode 24 is connected to the seventh microstrip line 7, and the cathode is connected to the tenth microstrip line 10. The anode of the fourth diode 25 is connected to the eleventh microstrip line 11, and the cathode is connected to the seventh microstrip line 7.

[0066] As one of the preferred embodiments, the harmonic suppression part of the two-stage Cascade voltage multiplier rectifier structure (II) is composed of three capacitors and six microstrip lines. The three capacitors are a third capacitor (26), a fourth capacitor 27, and a fifth capacitor 28. The six microstrip lines are a twelfth microstrip line 12, a thirteenth microstrip line 13, a fourteenth microstrip line 14, a fifteenth microstrip line 15, a sixteenth microstrip line 16, and a nineteenth microstrip line 19.

[0067] Among them, the third capacitor 26 is connected to the twelfth microstrip line 12 and the thirteenth microstrip line 13 respectively. The twelfth microstrip line 12 is vertically connected to the eighth microstrip line 8 and the sixteenth microstrip line 16, and the end of the twelfth microstrip line 12 is connected to the underlying metal floor through a metalized via. The fourth capacitor 27 is connected to the thirteenth microstrip line 13 and the fourteenth microstrip line 14 respectively. The thirteenth microstrip line 13 is vertically connected to the ninth microstrip line 9 and the tenth microstrip line 10. The fifth capacitor 28 is connected to the fourteenth microstrip line 14 and the fifteenth microstrip line 15 respectively. The fourteenth microstrip line 14 is vertically connected to the eleventh microstrip line 11 and the nineteenth microstrip line 19. The end of the fifteenth microstrip line 15 is connected to the underlying metal floor through a metalized via.

[0068] As one of the preferred embodiments, the load end of the two-stage Cascade voltage multiplier rectifier structure (II) is composed of a first resistor 29 and the seventeenth microstrip line 17 and the eighteenth microstrip line 18. The seventeenth microstrip line 17 is vertically connected to the sixteenth microstrip line 16. The eighteenth microstrip line 18 is vertically connected to the nineteenth microstrip line 19. The two ends of the first resistor 29 are connected to the seventeenth microstrip line 17 and the eighteenth microstrip line 18. The selection of the first resistor 29 will affect the rectification efficiency of the rectifier circuit. This embodiment uses the source impedance pull simulation method to determine that the load is 1200Ω, ensuring that the rectifier circuit has a high rectification efficiency.

[0069] The T-type broadband matching network I is composed of a first microstrip line 1, a second microstrip line 2, a third microstrip line 3, a fourth microstrip line 4, and a fifth microstrip line 5. The first microstrip line 1 is perpendicular to the second microstrip line 2 and the third microstrip line 3, and the fourth microstrip line 4 is parallel to the fifth microstrip line 5. The first microstrip line 1 is located to the left of the second microstrip line 2 and the third microstrip line 3. The second microstrip line 2 is perpendicular to the fourth microstrip line 4 and is located to the left of the fourth microstrip line 4. The third microstrip line 3 is perpendicular to the fifth microstrip line 5 and is located to the left of the fifth microstrip line 5.

[0070] In one preferred embodiment, the left end of the first microstrip line 1 is connected to the input signal source port P, and the right end is vertically connected to the second microstrip line 2 and the third microstrip line 3. The left end of the fourth microstrip line 4 is vertically connected to the second microstrip line 2, and the right end is connected to the first capacitor 20. The left end of the fifth microstrip line 5 is vertically connected to the third microstrip line 3, and the right end is connected to the second capacitor 21.

[0071] The structure of a broadband high-efficiency rectifier circuit in this embodiment is as follows: Figure 2As shown below, it is only a preferred embodiment of the present invention. The dielectric substrate used in this example is Arlon-AD255C, which has a thickness of 0.762 mm, a relative dielectric constant of 2.55, and a loss tangent of 0.0018. The specific circuit dimensions are as follows: the length of the first microstrip line 1 is 2.9 mm, the width is 2.2 mm; the length of the second microstrip line 2 is 2 mm, the width is 0.9 mm; the length of the third microstrip line 3 is 2 mm, the width is 0.9 mm; the length of the fourth microstrip line 4 is 1.2 mm, the width is 0.9 mm; the length of the fifth microstrip line 5 is 1.2 mm, the width is 0.9 mm; the length of the sixth microstrip line 6 is 2.5 mm, the width is 0.8 mm; the length of the seventh microstrip line 7 is 2.5 mm, the width is 0.8 mm; the length of the eighth microstrip line 8 is 1.5 mm, the width is 0.8 mm; the length of the ninth microstrip line 9 is 1.1 mm, the width is 0.8 mm; the length of the tenth microstrip line 10 is 1.1 mm, the width is 0.8 mm; the length of the eleventh microstrip line 11 is 1.5 mm, the width is 0.8 mm; the length of the twelfth microstrip line 1 2 has a length of 3.3 mm and a width of 0.8 mm; the thirteenth microstrip line 13 has a length of 3.6 mm and a width of 0.8 mm; the fourteenth microstrip line 14 has a length of 2.1 mm and a width of 0.8 mm; the fifteenth microstrip line 15 has a length of 2.4 mm and a width of 0.8 mm; the sixteenth microstrip line 16 has a length of 3.3 mm and a width of 0.8 mm; the seventeenth microstrip line 17 has a length of 2.7 mm and a width of 0.8 mm; the eighteenth microstrip line 18 has a length of 2.7 mm and a width of 0.8 mm; the nineteenth microstrip line 19 has a length of 3.3 mm and a width of 0.8 mm; the first capacitor 20 has a length of 47 pF; the second capacitor 21 has a length of 47 pF; the third capacitor 26 has a length of 330 pF; the fourth capacitor 27 has a length of 330 pF; the fifth capacitor 28 has a length of 330 pF; and the load resistor 29 has a length of 1200 Ω. The overall size of the circuit is 15mm×10mm.

[0072] See Figure 3 The simulation and test results of the axial ratio of the receiving antenna described in this embodiment of the present invention at 1 GHz to 4 GHz are shown. The vertical axis represents the axial ratio in dB. Although there is a certain frequency offset between the simulation and test results, the axial ratio bandwidth is generally consistent. This indicates that the antenna exhibits broadband circular polarization characteristics.

[0073] See Figure 4 This is the directivity pattern of the receiving antenna according to an embodiment of the present invention tested in a microwave anechoic chamber at 2.4 GHz. The ordinate represents the directivity coefficient in dBic. The difference between left-hand circular polarization and right-hand circular polarization in the +z or -z directions is 10 dB, meaning the cross-polarization is less than -10 dB. This indicates that the antenna exhibits dual circular polarization characteristics.

[0074] See Figure 5Simulation and test results of the return loss of the rectifier circuit according to an embodiment of the present invention from 0 GHz to 4.5 GHz at an input power of 18 dBm. The vertical axis in the figure represents the return loss in dB. Although there is a certain frequency offset between the simulation and test results, the bandwidth range is generally consistent.

[0075] See Figure 6 Simulation and test results of the energy conversion efficiency of the rectenna embodiment of the present invention at 1 GHz to 4 GHz at an input power of 18 dBm. The vertical axis in the figure represents the energy conversion efficiency in percent. As can be seen, the rectenna achieves a rectification efficiency of 55% near the operating frequency. The slight difference between the measured and simulated results in the figure is due to circuit processing errors and is within an acceptable range.

[0076] In summary, the present invention proposes an ultra-wideband dual circularly polarized rectenna. The rectenna expands the bandwidth by adding U-shaped branches and realizes dual circular polarization by dual-port coplanar waveguide feeding. The secondary Cascade voltage-doubling rectifier structure is adopted to improve the energy conversion efficiency, so that the disclosed rectenna can achieve high energy conversion efficiency within an ultra-wideband. At the same time, compared with the existing broadband dual circularly polarized rectenna, the above scheme has a wider axial ratio bandwidth, a simpler structure, a smaller size, and a lower cost.

[0077] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An ultra-wideband dual circularly polarized rectenna, characterized in that: include: A receiving antenna and a rectifier circuit, wherein the receiving antenna and the rectifier circuit are connected together via an SMA connector; The receiving antenna includes a first dielectric substrate, a first metal floor, a main radiation patch and a first microstrip structure; the first metal floor, the first microstrip structure and the main radiation patch are all printed on the upper surface of the first dielectric substrate; The rectifier circuit includes a second microstrip structure, a second dielectric substrate, and a second metal floor. The second microstrip structure is printed on the upper surface of the second dielectric substrate, and the second metal floor is printed on the lower surface of the second dielectric substrate.

2. The ultra-wideband dual circularly polarized rectenna according to claim 1, wherein: The first metal floor is a square ring-shaped metal floor, and the square ring-shaped metal floor is formed by opening a square hole in the center of the square metal floor; Two rectangular grooves are etched on two adjacent sides of the square annular metal floor, and two rectangular gaps are etched on the other two sides of the square annular metal floor. The two rectangular gaps form a first port and a second port respectively.

3. The ultra-wideband dual circularly polarized rectenna according to claim 1, wherein: The main body of the main radiation patch is composed of a square patch with two cut corners; The cut corners are formed by cutting off two isosceles triangles from two opposite corners of the square patch; Two U-shaped branches are provided at one of the cut corners.

4. The ultra-wideband dual circularly polarized rectenna according to claim 2, wherein: The first microstrip structure is composed of a first microstrip main line, a second microstrip main line, and a third microstrip main line, wherein one end of the first microstrip main line and the second microstrip main line are respectively connected to the main radiation patch, and the other ends of the first microstrip main line and the second microstrip main line are respectively connected to the first port and the second port; The third microstrip main line is arranged at the center of another cut angle opposite to the cut angle where the U-shaped branch of the main radiation patch is located, one end of the third microstrip main line is connected to the main radiation patch, and the other end of the third microstrip main line is connected to the first metal floor.

5. The ultra-wideband dual circularly polarized rectenna according to claim 1, wherein: The rectifier circuit also includes a T-type broadband matching network and a two-stage Cascade voltage multiplier rectifier structure; The second microstrip structure is composed of a T-type broadband matching network and a microstrip line in a two-stage Cascade voltage doubler rectifier structure; The T-type broadband matching network includes a first microstrip line, a second microstrip line, a third microstrip line, a fourth microstrip line, and a fifth microstrip line; in, The first microstrip line is perpendicular to the second microstrip line and the third microstrip line, and the fourth microstrip line is parallel to the fifth microstrip line; The first microstrip line is located on the left side of the second microstrip line and the third microstrip line; The second microstrip line is perpendicular to the fourth microstrip line, and the second microstrip line is located on the left side of the fourth microstrip line; The third microstrip line is perpendicular to the fifth microstrip line, and the third microstrip line is located on the left side of the fifth microstrip line.

6. The ultra-wideband dual circularly polarized rectenna according to claim 5, wherein: The rectifier circuit further includes a patch component, and the patch component includes a first diode, a second diode, a third diode, and a fourth diode; The first diode is vertically connected to the second diode, and the second diode is located on the left side of the first diode; The third diode is vertically connected to the fourth diode, and the fourth diode is located on the left side of the third diode.

7. The ultra-wideband dual circularly polarized rectenna according to claim 6, wherein: The patch component further includes a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor and a first resistor; The two-stage Cascade voltage multiplier rectifier structure further includes a sixth microstrip line, a seventh microstrip line, an eighth microstrip line, a ninth microstrip line, a tenth microstrip line, an eleventh microstrip line, a twelfth microstrip line, a thirteenth microstrip line, a fourteenth microstrip line, a fifteenth microstrip line, a sixteenth microstrip line, a seventeenth microstrip line, an eighteenth microstrip line, and a nineteenth microstrip line; The first capacitor is located between the fourth microstrip line and the sixth microstrip line, and the fourth microstrip line is located on the left side of the sixth microstrip line; The second capacitor is located between the fifth microstrip line and the seventh microstrip line, and the fifth microstrip line is located on the left side of the seventh microstrip line; The first diode is located between the sixth microstrip line and the eighth microstrip line, the sixth microstrip line is parallel to the eighth microstrip line, and the eighth microstrip line is located on the right side of the sixth microstrip line; The second diode is located between the sixth microstrip line and the ninth microstrip line, the sixth microstrip line is parallel to the ninth microstrip line, and the ninth microstrip line is located on the right side of the sixth microstrip line; The third diode is located between the seventh microstrip line and the tenth microstrip line, the seventh microstrip line is parallel to the tenth microstrip line, and the tenth microstrip line is located on the right side of the seventh microstrip line; The fourth diode is located between the seventh microstrip line and the eleventh microstrip line, the seventh microstrip line is parallel to the eleventh microstrip line, and the eleventh microstrip line is located on the right side of the seventh microstrip line; The eighth microstrip line, the ninth microstrip line, the tenth microstrip line, and the eleventh microstrip line are parallel. The twelfth microstrip line is perpendicular to the eighth microstrip line and is located on the right side of the eighth microstrip line. The thirteenth microstrip line is perpendicular to the ninth microstrip line and the tenth microstrip line, and the thirteenth microstrip line is located on the right side of the ninth microstrip line and the tenth microstrip line; The fourteenth microstrip line (14) is perpendicular to the eleventh microstrip line (11), and the eleventh microstrip line is located on the left side of the fourteenth microstrip line.

8. The ultra-wideband dual circularly polarized rectenna according to claim 7, wherein: The third capacitor is located between the twelfth microstrip line and the thirteenth microstrip line, and an end of the twelfth microstrip line is connected to the second metal ground through a metal via; The fourth capacitor is located between the thirteenth microstrip line and the fourteenth microstrip line. The fifth capacitor is located between the fourteenth microstrip line and the fifteenth microstrip line, and an end of the fifteenth microstrip line is connected to the second metal ground through a metal via; The sixteenth microstrip line is perpendicular to the twelfth microstrip line and the seventeenth microstrip line, and the sixteenth microstrip line is located on the right side of the twelfth microstrip line; The nineteenth microstrip line is perpendicular to the fourteenth microstrip line and the eighteenth microstrip line, and the nineteenth microstrip line is located on the right side of the fourteenth microstrip line; The first resistor is located between the seventeenth microstrip line and the eighteenth microstrip line.

9. The ultra-wideband dual circularly polarized rectenna according to any one of claims 1 to 8, characterized in that: The ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the axial ratio bandwidth of the ultra-wideband dual circularly polarized rectenna is 1.35-3.37 GHz.

10. The ultra-wideband dual circularly polarized rectenna according to any one of claims 1 to 8, characterized in that: The ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the operating bandwidth of the ultra-wideband dual circularly polarized rectenna is 1.35-3.37 GHz.

11. The ultra-wideband dual circularly polarized rectenna according to any one of claims 1 to 8, characterized in that: The ultra-wideband dual circularly polarized rectenna is applied to a wireless energy transmission system, wherein the operating input power of the ultra-wideband dual circularly polarized rectenna is 18 dBm.

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