Circularly polarized polarization selective wireless energy harvesting rectifier

Abstract

This invention discloses a circularly polarized selective wireless energy harvesting rectifier, comprising a metasurface module, a power combining module, and a rectification module. The metasurface module includes multiple absorbing units arranged in a periodic array. Each absorbing unit includes a resonant structure on the front side of a dielectric substrate and a metallized via penetrating the substrate. The resonant structure is a conductive ring with two offset openings, one of which contains a capacitive element. The power combining module includes a power combining network disposed on the back side of the dielectric layer of the power combining network. The input terminal of the rectification module is connected to the output terminal of the power combining module. This rectifier simultaneously solves the two core problems of polarization mismatch and bandwidth limitation. It integrates polarization selection, wideband energy harvesting, and high-efficiency rectification functions. Its core function is to efficiently selectively absorb and convert right-hand circularly polarized waves while generating strong reflection of left-hand circularly polarized waves to suppress interference.

Description

Technical Field

[0001] This invention relates to an electromagnetic energy harvesting rectifier, specifically a circularly polarized polarization-selective wireless energy harvesting rectifier. Background Technology

[0002] In recent years, Wireless Energy Harvesting (WEH) technology has developed rapidly, attracting significant attention from academia and industry as a core technology enabling 5G communication and the Internet of Things. While short-range wireless power transfer technologies such as magnetic induction coupling and magnetic resonance coupling have been gradually commercialized, microwave radiating wireless power supply technology for long-range applications still faces multiple challenges related to efficiency, stability, and integration. Especially in complex electromagnetic environments, energy transmission is highly susceptible to polarization mismatch, frequency shift, and multipath interference, severely limiting the energy conversion efficiency at the receiver. Therefore, developing rectifier antenna technology that combines high efficiency, polarization selectivity, and wide bandwidth has become a key path to overcome the bottlenecks in long-range WEH technology.

[0003] The concept of WEH (Power Receiver) was proposed relatively early, but it has only gradually become practical in recent years with the development of micro-nano fabrication, semiconductor technology, and metamaterials. In low-power applications such as 5G, IoT, and wearable devices, WEH can provide an ideal power supply solution for continuous online operation. However, traditional rectifier antennas, which use a cascaded design of discrete antennas and rectifier circuits, suffer from problems such as large size, high loss, and complex impedance matching. More seriously, traditional rectifier antennas are extremely sensitive to polarization mismatch. Because they are mostly based on linear polarization design, even a small change in polarization direction can cause a sharp drop in energy reception efficiency of more than 50% in dynamic scenarios such as mobile terminals or complex electromagnetic environments, becoming a key bottleneck affecting the practical application of this technology.

[0004] To address polarization sensitivity, existing technologies largely employ circularly polarized antenna schemes; however, their implementation still faces significant bottlenecks. For instance, circularly polarized antennas based on sequential rotation feeding or multi-feed structures generally suffer from high design complexity and integration difficulties. While some metasurface rectification schemes have improved integration, they often struggle to achieve effective circular polarization selectivity or experience significant performance degradation when encountering oppositely polarized waves or co-channel interference. Furthermore, existing solutions generally do not adequately prioritize bandwidth performance; most designs fail to cover a sufficient frequency range while maintaining high conversion efficiency, making them unsuitable for complex application scenarios involving frequency drift or the coexistence of multiple frequency bands in real-world environments.

[0005] Against this backdrop, this invention proposes a circularly polarized selective wireless energy harvesting rectifier. The core of this rectifier lies in its deep integration of selective capture of circularly polarized waves with efficient rectification via an asymmetric metasurface structure, forming an integrated energy harvesting system. This system not only selectively captures circularly polarized wave energy of specific directions (e.g., right-handed), effectively suppressing reverse-rotation waves and co-channel interference, but also achieves a wide bandwidth of 1.3 GHz at a center frequency of 5.8 GHz through impedance optimization at the structural level. This effectively improves the system's tolerance to frequency drift and adaptability to complex electromagnetic environments, providing a practical technical path for constructing a highly reliable and adaptive next-generation wireless energy harvesting system. Summary of the Invention

[0006] To address the application requirements of frequency drift or multi-band signals in practical environments, this invention provides a circularly polarized selective wireless energy harvesting rectifier. This rectifier integrates polarization selection, wideband energy harvesting, and high-efficiency rectification. Its core function is the efficient selective absorption and energy conversion of right-hand circularly polarized waves, while simultaneously generating strong reflection of left-hand circularly polarized waves to suppress interference. Within the operating frequency band of 5.3–6.6 GHz (1.3 GHz bandwidth), the overall rectification efficiency remains stable at over 60%. This design effectively improves the stability and reliability of the system in complex electromagnetic environments by simultaneously solving the two core challenges of polarization mismatch and bandwidth limitation, effectively overcoming the shortcomings of traditional solutions in terms of efficiency, bandwidth, and anti-interference capabilities.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a circularly polarized polarization-selective wireless energy harvesting rectifier, comprising a metasurface module, a power combining module and a rectifier module;

[0008] The metasurface module includes multiple absorbing units arranged in a periodic array for polarization-selective absorption of circularly polarized electromagnetic waves with a specific rotation direction. Each absorbing unit includes a resonant structure on the front side of a dielectric substrate and a metallized via penetrating the dielectric substrate. The metallized via connects the resonant structure to the input port of the power combining module. The resonant structure is a conductive ring with two position biasing openings. The two position biasing openings include a capacitive opening trench located on the lower right side of the conductive ring and a resistive opening trench located on the bottom right side of the conductive ring. A capacitive element is loaded in the capacitive opening trench, and metallized vias are symmetrically arranged on both sides of the resistive opening trench.

[0009] The power combining module includes a power combining network disposed on the back side of the dielectric layer of the power combining network, wherein the dielectric layer of the power combining network is disposed on the back side of the absorbing unit, and the power combining network is composed of multiple cascaded dual-channel power combining units; each dual-channel power combining unit includes two impedance transformation transmission segments, two port transition segments, and a backbone transmission segment connected thereto; the multiple dual-channel power combining units are connected step-by-step through several node compensation segments and several backbone connection segments; the two port transition segments of each dual-channel power combining unit are electrically connected to two metallized vias of an absorbing unit; the power combining module is used to perform equal-phase combining of the radio frequency energy output from each absorbing unit and then output it;

[0010] The rectifier module, whose input terminal is connected to the output terminal of the power combining module, is used to convert the combined radio frequency energy into DC energy.

[0011] This invention enables the metasurface module to distinguish between circularly polarized waves of different rotational directions by setting two offset openings on the conductive ring of the absorbing unit and loading a capacitive element in one of the openings. This structural design allows the rectifier to preferentially receive circularly polarized waves of the target rotational direction while suppressing interference signals of the opposite rotational direction, laying the foundation for stable operation in complex electromagnetic environments.

[0012] The asymmetrical design of the offset positions of the capacitive and resistive opening trenches enables the absorbing unit to exhibit different response characteristics to circularly polarized waves with different directions of rotation. The capacitive opening with a loaded capacitor further enhances this selectivity. This structural design allows the metasurface module to exhibit high absorption characteristics for right-handed circularly polarized waves while strongly reflecting left-handed circularly polarized waves, achieving polarization-selective absorption.

[0013] The power combining network is located on the back of the dielectric layer of the power combining network, behind the absorbing units, and does not occupy additional planar space. The power combining network adopts a multi-stage cascaded structure of two-way power combining units, which can gradually converge the RF energy of multiple absorbing units to the output of the power combining module. Each two-way power combining unit includes two impedance transformation transmission segments, two port transition segments, and a main transmission segment connected to them. With the help of node compensation segments and main connection segments, the phase of each branch signal is consistent when it arrives at the combining point. This structural design avoids the complex structure of additional matching circuits and multiple rectifier inputs required when each absorbing unit outputs alone, and reduces the connection loss and impedance matching difficulty caused by distributed output. At the same time, equiphase combining ensures that the RF energy of multiple channels can be efficiently combined, improves the equivalent power level input to the rectifier module, reduces the combining loss caused by phase inconsistency, and helps to improve the overall energy conversion efficiency. The impedance transformation transmission segments are preferably one-quarter of the guide wavelength electrical length near the operating frequency, and their physical length is determined after optimization through electromagnetic simulation. Preferably, each absorbing unit includes a loss-absorbing thin film, a loss-dielectric layer, and an intermediate metal layer stacked from top to bottom. The resonant structure is a square conductive ring in the form of a metal pattern etched on the loss-absorbing thin film. The power combining network dielectric layer is disposed on the back side of the intermediate metal layer. The conductive ring pattern on the loss-absorbing thin film is used to capture electromagnetic energy; the intermediate metal layer acts as a reflector. By precisely designing the thickness of the loss-dielectric layer and the conductive ring pattern on the loss-absorbing thin film, a resonant cavity effect is formed between the loss-absorbing thin film and the intermediate metal layer, thereby significantly improving the absorption efficiency of electromagnetic waves in a specific frequency band. Metallized vias guide the captured radio frequency energy from the resonant structure and send it to the power combining module, realizing efficient energy transmission.

[0014] Preferably, the characteristic impedance of the impedance transformation transmission line segment is 70–75Ω and the line width W5 is 0.9–1.2mm; the characteristic impedance of the main transmission line segment is 50Ω and the line width W4 is 1.8–2.2mm; and the line width W3 of the port transition line segment is 0.6–1.0mm. The main transmission line segment uses a 50Ω characteristic impedance for easy matching with standard RF interfaces. The impedance transformation transmission line segment uses a 70–75Ω characteristic impedance to perform impedance transformation, matching the output impedance of the absorbing unit with the main transmission line. The port transition line segment uses a thinner line width to achieve a smooth transition from the pad or via to the transmission line. These parameters are optimized to maintain low transmission loss within the operating frequency band, ensuring the efficiency of multi-path energy combining.

[0015] Preferably, the plurality of absorbing units are arranged in a 4×4 array with a periodic side length P1 of 9–11 mm; the thickness H1 of the loss dielectric layer is the same as the thickness H5 of the power combining network dielectric layer, and H1 = H5 = 1.4–1.7 mm; the thickness H2 of the loss absorption film and the thickness H3 of the intermediate metal layer are the same as the thickness H4 of the power combining module, and H2 = H3 = H4 = 0.03–0.04 mm; the length Px of the conductive ring and The width of each layer (Py) is 8.5–8.8 mm. The linewidth of the conductive ring in the x-direction (Wx) is 3–3.5 mm, and the linewidth in the y-direction (Wy) is 1.4–1.7 mm. The gap width of the capacitive opening trench (Wc) is 1–1.6 mm. The opening width of the resistive opening trench (Wr) is 0.2–0.6 mm. The radius (r) of the metallized via is 0.3–0.6 mm. The capacitive element is a surface-mount capacitor with a capacitance of 0.1–0.3 pF. The parameters such as the periodic side length, layer thickness, conductive ring size, opening size, and via radius are all optimized within a certain range, enabling the 4×4 array-scale absorbing unit to maintain an absorption rate of over 85% for right-hand circularly polarized waves in the 5.3–6.6 GHz frequency band (reaching 97% at 5.8 GHz). The capacitance value range of 0.1–0.3 pF ensures the realization of circular polarization selectivity. The combination of these dimensional parameters enables the rectifier to maintain stable absorption performance over a wide frequency range.

[0016] Preferably, the rectifier module sequentially includes an impedance matching section, a rectification section, and a filtering section disposed on the dielectric substrate. The impedance matching section includes a first microstrip line stub and a second microstrip line stub disposed on the first connection section. The rectification section employs a voltage doubler rectifier circuit. The rectification section includes a DC filter capacitor and a Schottky diode disposed on the second connection section. The first connection section is electrically connected to the second connection section via the DC filter capacitor. The filtering section includes a sector-shaped harmonic suppression unit, a filter capacitor, a grounding via, and a load connection terminal disposed on the third connection section. The sector-shaped harmonic suppression unit cooperates with the grounding via to suppress harmonic components. The load connection terminal is used to lead out the rectified DC output. The impedance matching section uses the above-mentioned dual-stub microstrip line structure for impedance matching, which can achieve good matching effect over a wide frequency range. The voltage doubler rectifier circuit uses a Schottky diode, which is suitable for low-power RF energy rectification. The sector-shaped harmonic suppression unit cooperates with the grounding via to effectively filter out harmonic components generated during rectification and reduce energy loss. The load connection terminal is used to output smooth DC power. This circuit design enables the rectifier module to maintain a rectification efficiency of over 50% in the 5.3–7.5 GHz range.

[0017] Preferably, the rectifier module has a linewidth W of 2.7–2.9 mm; the first microstrip line stub has a width W1 of 1.8–2 mm and a length L8 of 11–12 mm; the second microstrip line stub has a width W2 of 2.1–2.3 mm and a length L9 of 13–14 mm; the distance between the first and second microstrip line stubs is L2 = 9.8–10.1 mm; and the distance between the second microstrip line stub and the DC filter capacitor is L3 = 6.9–7 mm. The distance L4 between the DC filter capacitor and the Schottky diode is 8.8–9 mm; the width Wi of the sector-shaped harmonic suppression unit is 1.5–1.7 mm, the length L is 3.9–4.1 mm, and the rotation angle A is 65–75°; the radius of the grounding via is equal to the radius of the metallized via; the capacitance of the DC filter capacitor is 680 nF, the capacitance of the filter capacitor is 470 nF, and the Schottky diode is HSMS286C. The width, length, and spacing of the first and second microstrip line stubs are optimized to ensure good matching of the dual-stub matching network over a wide frequency band. The size and angle of the sector-shaped harmonic suppression unit are optimized for second and third harmonics. The 680 nF DC filter capacitor is used for DC blocking and RF passing, and the 470 nF filter capacitor is used for smoothing DC output. The HSMS286C Schottky diode is suitable for RF rectification in the 2–8 GHz frequency band. The combination of these parameters and component selections enables the rectifier module to achieve a rectification efficiency of approximately 70% around 5.8GHz.

[0018] Preferably, the loss dielectric layer, power combining network dielectric layer, and dielectric substrate are all made of FR4 dielectric material, which has a relative permittivity of 4.3 and a loss tangent of 0.025. FR4 dielectric material possesses excellent high-frequency performance and mechanical strength. The use of FR4 dielectric material in the loss dielectric layer of the metasurface module, the power combining network dielectric layer, and the dielectric substrate of the rectifier module facilitates standardized procurement and processing. The use of FR4 dielectric material allows the entire rectifier to be manufactured using standard PCB processes, reducing manufacturing costs and process complexity.

[0019] Preferably, the power combining module and the rectifier module are connected via a coaxial connector. Using a coaxial connector (such as an SMA connector) facilitates independent debugging and performance measurement of the power combining module and the rectifier module during the R&D and testing phases. After debugging, the decision to retain the connector or switch to a direct connection can be made based on actual application requirements. This design improves development and testing flexibility and helps shorten the R&D cycle.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) Achieved selective absorption and anti-interference capability for circularly polarized waves with specific rotation directions: The core of the rectifier in this invention lies in the structural design of its metasurface module. Each absorbing unit adopts a conductive ring with two offset openings, and a capacitive element is loaded in one of the openings. This asymmetric structure enables the metasurface module to produce differentiated responses to circularly polarized waves with different rotation directions. According to simulation results, in the 5.3-6.6 GHz frequency band, the absorption rate of this structure for right-hand circularly polarized waves can be maintained above 85%, and the absorption rate reaches 97% at the center frequency of 5.8 GHz; while for non-target left-hand circularly polarized waves, strong reflection occurs, accompanied by polarization conversion. This characteristic enables the rectifier to effectively capture the energy of the target band, while suppressing reverse-rotation waves and co-channel interference, solving the problem of a significant decrease in receiving efficiency caused by polarization mismatch in complex electromagnetic environments for traditional linearly polarized antennas.

[0022] (2) Possesses wideband operating characteristics and strong environmental adaptability: The rectifier of this invention can achieve stable energy harvesting and conversion in the frequency range of 5.3 to 6.6 GHz, with a relative bandwidth of approximately 21.8%. Within this frequency band, through the synergistic effect of the wideband absorption characteristics of the metasurface module and the wideband matching design of the rectifier module, the overall rectification efficiency of the rectifier remains above 60%, demonstrating excellent wideband operating capability. This wideband characteristic gives it high tolerance to frequency deviations, enabling it to maintain stable DC output in real-world environments with fluctuating signal frequencies or coexistence of multiple frequency bands. Compared to the sensitivity of traditional narrowband rectifier antennas to frequency changes, this design offers improved adaptability and reliability in complex electromagnetic environments. Attached Figure Description

[0023] Figure 1 Here are simplified schematic diagrams of the rectifier structures in Examples 1 and 2;

[0024] Figure 2 This is a front view of the absorbing metasurface module of the rectifier in Example 1;

[0025] Figure 3 This is a side view of the absorbing metasurface module of the rectifier in Example 1, after being enlarged by scale.

[0026] Figure 4 This is a front view of the absorbing unit in Example 1;

[0027] Figure 5 This is the network view of the power combining module in Example 1;

[0028] Figure 6 This is a magnified view of the power combining module network in Example 1, with dimension parameters labeled.

[0029] Figure 7 This is a view of the rectifier module in Example 1;

[0030] Figure 8 This is a view of the rectifier module in Example 1 with dimension parameters labeled;

[0031] Figure 9 The above is a simulation curve of the S-parameters of the absorbing unit in Example 1 when a circularly polarized electromagnetic wave is incident perpendicularly along the -Z direction.

[0032] Figure 10 The simulation curves of the absorption efficiency of the absorbing unit in Examples 1 and 2 when the circularly polarized electromagnetic wave is incident perpendicularly along the -Z direction are shown.

[0033] Figure 11 The simulation curve of the rectification efficiency of the rectifier module in Example 1 is shown.

[0034] Figure 12 Simulation curves of the rectification efficiency of the rectifiers in Example 1 and Example 2;

[0035] Figure 3 , 4 The dimensions in sections 6 and 8 are all marked in red.

[0036] Figures 1 to 7 The specific reference numerals in the attached figures are as follows:

[0037] 1-Metasurface module, 2-Absorbing unit, 3-Rectifying module, 4-Loss absorption film, 5-Loss dielectric layer, 6-Metallized via, 7-Intermediate metal layer, 8-Capacitive element, 9-First conductive sheet, 10-Second conductive sheet, 11-Power combining module, 12-Main transmission line segment, 13-Impedance transformation transmission line segment, 14-Port transition line segment, 15-Capacitive opening trench, 16-Resistive opening trench, 17-Impedance matching section, 18-Rectifying section, 19- Filtering section, 20-First microstrip line stub, 21-Second microstrip line stub, 22-DC filter capacitor, 23-Schottky diode, 24-Filter capacitor, 25-Grounding via, 26-Load connection terminal, 27-SMA connector, 28-Power combining network dielectric layer, 29-Node compensation section, 30-Backbone connection section, 31-Fan-shaped harmonic suppression unit, 32-First connection section, 33-Second connection section, 34-Third connection section, 35-Output terminal, 36-Dielectric board. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0039] Example 1: Circularly polarized polarization-selective wireless energy harvesting rectifier, such as Figures 1 to 8As shown, the rectifier includes a metasurface module 1, a power combining module 11, and a rectifier module 3. The metasurface module 1 includes 16 absorbing units 2 arranged in a 4×4 array for polarization-selective absorption of circularly polarized electromagnetic waves with a specific rotation direction. Each absorbing unit 2 includes a resonant structure on the front side of the dielectric substrate and a metallized via 6 penetrating the substrate. The metallized via 6 connects the resonant structure to the input port of the power combining module 11. The resonant structure is a conductive ring with two offset openings. The power combining module 11 has 16 input ports connected to each absorbing unit 2 via the metallized via 6, and is used to combine the RF energy output from each absorbing unit 2 in equal phase before outputting it through its output terminal 35. The rectifier module 3 has its input terminal connected to the output terminal 35 of the power combining module 11 via a coaxial connector, and is used to convert the combined RF energy into DC energy. In this example 1, the coaxial connector is specifically an SMA connector 27.

[0040] In Example 1, each absorbing unit 2 includes a loss-absorbing thin film 4, a loss-dielectric layer 5, and an intermediate metal layer 7 stacked from top to bottom. The resonant structure is a square conductive ring in the form of a metal pattern etched on the loss-absorbing thin film 4. The two biased openings include a capacitive opening trench 15 located on the lower right side of the conductive ring and a resistive opening trench 16 located on the bottom right side of the conductive ring. A capacitive element 8 is loaded in the capacitive opening trench 15. Metallized vias 6 are symmetrically arranged on both sides of the resistive opening trench 16. The capacitive opening trench 15 and the resistive opening trench 16 divide the conductive ring into a first conductive sheet 9 and a second conductive sheet 10. The capacitive element 8 is electrically connected to the first conductive sheet 9 and the second conductive sheet 10, respectively. A metallized via 6 is provided on each of the first conductive sheet 9 and the second conductive sheet 10.

[0041] In Example 1, the power combining module 11 adopts symmetrical wiring on the left and right and top and bottom. Specifically, it includes a power combining network disposed on the back of the power combining network dielectric layer 28. The power combining network dielectric layer 28 is disposed on the back of the intermediate metal layer 7. The power combining network is composed of multiple levels of cascaded two-way power combining units. Each two-way power combining unit includes two impedance transformation transmission segments 13, two port transition segments 14, and a trunk transmission segment 12 connected to them. The multiple levels of two-way power combining units are connected step by step through several node compensation segments 29 and several trunk connection segments 30. Finally, the output terminal 35 of the power combining module 11 outputs to achieve consistent electrical length of each branch. The two port transition segments 14 of each two-way power combining unit are electrically connected to the two metallized through holes 6 of an absorbing unit 2.

[0042] In Example 1, the rectifier module 3 sequentially includes an impedance matching section 17, a rectification section 18, and a filtering section 19 disposed on the dielectric substrate 36. The impedance matching section 17 includes a first microstrip line stub 20 and a second microstrip line stub 21 disposed on the first connection section 32. The rectification section 18 adopts a voltage doubler rectifier circuit and includes a DC filter capacitor 22 and a Schottky diode 23 disposed on the second connection section 33. The first connection section 32 is electrically connected to the second connection section 33 via the DC filter capacitor 22. The filtering section 19 includes a sector harmonic suppression unit 31, a filter capacitor 24, a grounding via 25, and a load connection terminal 26 disposed on the third connection section 34. The sector harmonic suppression unit 31 and the grounding via 25 cooperate to suppress harmonic components. The load connection terminal 26 is used to lead out the rectified DC output.

[0043] In Example 1, the characteristic impedance of impedance transformation transmission segment 13 is 70–75Ω, and the line width W5 is 0.9–1.2 mm; the characteristic impedance of trunk transmission segment 12 is 50Ω, and the line width W4 is 1.8–2.2 mm; the line width W3 of port transition segment 14 is 0.6–1.0 mm; the length La of impedance transformation transmission segment 13 and the length Lb of port transition segment 14 satisfy La = Lb = 0.3–0.6 mm; the length Lc of node compensation segment 29 is 1.7–1.9 mm; the length Ld = Le = Lf = 3.9–4.1 mm at different locations of trunk connection segment 30. The impedance transformation transmission segment 13 is preferably one-quarter of the guide wavelength electrical length near the operating frequency, and its physical length is determined through electromagnetic simulation optimization.

[0044] In Example 1, the periodic side length P1 of the 16 absorbing units 2 is 9–11 mm; the thickness H1 of the loss dielectric layer 5 is the same as the thickness H5 of the power combining network dielectric layer 28, and H1 = H5 = 1.6 mm; the thickness H2 of the loss absorption film 4, the thickness H3 of the intermediate metal layer 7, and the thickness H4 of the power combining module 11 are the same, and H2 = H3 = H4 = 0.03–0.04 mm; the thickness of the dielectric plate 36 is 1.0 mm; the conductive ring... The length Px and width Py of the conductive ring are both 8.5-8.8 mm. The linewidth Wx of the conductive ring in the x direction is 3-3.5 mm, and the linewidth Wy in the y direction is 1.4-1.7 mm. The gap width Wc of the capacitive open groove 15 is 1-1.6 mm. The opening width Wr of the resistive open groove 16 is 0.2-0.6 mm. The radius r of the metallized through hole 6 is 0.3-0.6 mm. The capacitive element 8 is a surface-mount capacitor with a capacitance of 0.3 pF.

[0045] In Example 1, the linewidth W of the rectifier module 3 is 2.7–2.9 mm; the width W1 of the first microstrip stub 20 is 1.8–2 mm, and the length L8 is 11–12 mm; the width W2 of the second microstrip stub 21 is 2.1–2.3 mm, and the length L9 is 13–14 mm; the distance L1 between the first microstrip stub 20 and the input terminal of the rectifier module 3 is 3.1–3.4 mm; the distance L2 between the first microstrip stub 20 and the second microstrip stub 21 is 9.8–10.1 mm; the distance L3 between the second microstrip stub 21 and the DC filter capacitor 22 is 6.9–7.1 mm; and the distance L4 between the DC filter capacitor 22 and the Schottky diode 23 is 8.8 mm. ~9mm; the distance L5 between Schottky diode 23 and filter capacitor 24 is 3.1~3.4mm; the distance L6 between filter capacitor 24 and sector harmonic suppression unit 31 is 9~9.2mm; the distance L7 between sector harmonic suppression unit 31 and load connection terminal 26 is 4.1~4.3mm; the width Wi of sector harmonic suppression unit 31 is 1.5~1.7mm, the length L is 3.9~4.1mm, and the rotation angle A is 65~75°; the radius of grounding via 25 is equal to the radius of metallized via 6; the capacitance value of DC filter capacitor 22 is 680nF, the capacitance value of filter capacitor 24 is 470nF, and the model of Schottky diode 23 is HSMS286C.

[0046] In Example 1, the loss dielectric layer 5, the power combining network dielectric layer 28, and the dielectric substrate 36 are all made of FR4 dielectric material, with a relative permittivity of 4.3 and a loss tangent of 0.025.

[0047] The circularly polarized polarization-selective wireless energy harvesting rectifier in Example 2 has the same structure as the rectifier in Example 1, except that some parameters are different. Specifically, in Example 2, Wr=0.2mm, Wc=1.2mm, and the capacitive element 8 has a capacitance of 0.1pF.

[0048] Figure 9 This is a simulation curve of the S-parameters of the absorbing unit 2 of the energy harvesting rectifier in Example 1 when a circularly polarized electromagnetic wave is incident perpendicularly along the -Z direction. The incident electric field is along the y-direction and the incident magnetic field is along the x-direction. For specific directions, please refer to [reference needed]. Figure 2 The diagram shows a three-dimensional coordinate system. Because of the intermediate metal layer 7 in the structure, the transmission term within the operating frequency band can be ignored. Figure 9The S-parameters in the figure represent reflection coefficients. S-- represents the coefficient curves for left-hand circularly polarized wave incident and reflection, S+- represents the coefficient curves for left-hand circularly polarized wave incident and reflection, S++ represents the coefficient curves for right-hand circularly polarized wave incident and reflection, and S-+ represents the coefficient curves for right-hand circularly polarized wave incident and reflection. Circular polarization selectivity is achieved by setting a capacitive opening trench 15 at the lower right of the annular structure of the loss-absorbing thin film 4 and loading a chip capacitor. Figure 9 As can be seen, when a right-hand circularly polarized wave is incident, the absorption unit 2 exhibits S++≤-10 dB and S-+ significantly less than -10 dB in the frequency range of 5.3–6.6 GHz, indicating that the reflection is effectively suppressed. However, when a left-hand circularly polarized wave is incident, although S--≤-10 dB, S+- is close to 1 (or approximately 0 dB), indicating strong reflection of the left-hand circularly polarized incident wave, thus exhibiting polarization-selective absorption characteristics for the right-hand circularly polarized wave, with a relative bandwidth of 21.8%.

[0049] Figure 10 The simulation curves show the absorption efficiency of the absorbing unit 2 in Examples 1 and 2 when the circularly polarized electromagnetic wave is incident perpendicularly along the -Z direction. Figure 10 In this text, "Example 1A+" represents the absorption efficiency of the absorbing unit in Example 1 under right-hand circularly polarized wave irradiation, "Example 1A-" represents the absorption efficiency of the absorbing unit in Example 1 under left-hand circularly polarized wave irradiation, and "Example 1CD" represents the circular dichroism (CD) of the absorbing unit in Example 1. "Example 2A+" represents the absorption efficiency of the absorbing unit in Example 2 under right-hand circularly polarized wave irradiation, "Example 2A-" represents the absorption efficiency of the absorbing unit in Example 2 under left-hand circularly polarized wave irradiation, and "Example 2CD" represents the circular dichroism (CD) of the absorbing unit in Example 2. Circular dichroism refers to the physical phenomenon where a material or structure exhibits a difference in absorption rate to right-hand circularly polarized waves (RCP) and left-hand circularly polarized waves (LCP).

[0050] based on Figure 9 The S-parameters shown yielded the absorptivity curves. Example 1 exhibits a significant absorption peak at 5.8 GHz, with S++ and S-+ being significantly suppressed, achieving an absorption efficiency of approximately 97% for right-hand circularly polarized waves. Within the frequency range of 5.3–6.6 GHz, the absorptivity for right-hand circularly polarized waves remains above 85%. The absorption efficiency for left-hand circularly polarized waves is approximately 35%, remaining around 30% within the 5.3–6.6 GHz frequency range, demonstrating polarization selectivity. The CD value represents the absolute value of the difference in absorptivity between the two circularly polarized waves for this absorbing unit 2. Example 2, by adjusting the aperture width and capacitance value, achieves the same polarization selectivity characteristics, obtaining a wider rectified bandwidth while reducing the peak absorptivity.

[0051] Figure 11 This is a simulation curve of the rectification efficiency of rectifier module 3 in Example 1. When the input power is 14 dBm, broadband impedance matching is achieved through the double-stub impedance matching section 17, rectification is performed using a voltage doubler rectifier circuit, and broadband harmonic suppression is achieved using a fan-shaped harmonic suppression unit 31 and a filter capacitor 24, thereby improving the rectification efficiency over a wide frequency range. Figure 11 It can be seen that the rectification efficiency remains above 50% in the frequency range of 5.3 to 7.5 GHz, and can reach about 70% near 5.8 GHz. Figure 12 The figures show the simulation curves of the overall rectification efficiency of the energy harvesting rectifiers in Examples 1 and 2. Figure 12 It can be seen that the overall rectification efficiency of Examples 1 and 2 remains above 60% in the frequency range of 5.3 to 6.6 GHz.

Claims

1. A circularly polarized polarization-selective wireless energy harvesting rectifier, characterized in that, Includes metasurface modules, power combining modules, and rectifier modules; The metasurface module includes multiple absorbing units arranged in a periodic array for polarization-selective absorption of circularly polarized electromagnetic waves with a specific rotation direction. Each absorbing unit includes a resonant structure on the front side of a dielectric substrate and a metallized via penetrating the dielectric substrate. The metallized via connects the resonant structure to the input port of the power combining module. The resonant structure is a conductive ring with two position biasing openings. The two position biasing openings include a capacitive opening trench located on the lower right side of the conductive ring and a resistive opening trench located on the bottom right side of the conductive ring. A capacitive element is loaded in the capacitive opening trench, and metallized vias are symmetrically arranged on both sides of the resistive opening trench. The power combining module includes a power combining network disposed on the back side of the dielectric layer of the power combining network, wherein the dielectric layer of the power combining network is disposed on the back side of the absorbing unit, and the power combining network is composed of multiple cascaded dual-channel power combining units; each dual-channel power combining unit includes two impedance transformation transmission segments, two port transition segments, and a backbone transmission segment connected thereto; the multiple dual-channel power combining units are connected step-by-step through several node compensation segments and several backbone connection segments; the two port transition segments of each dual-channel power combining unit are electrically connected to two metallized vias of an absorbing unit; the power combining module is used to perform equal-phase combining of the radio frequency energy output from each absorbing unit and then output it; The rectifier module, whose input terminal is connected to the output terminal of the power combining module, is used to convert the combined radio frequency energy into DC energy.

2. The circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 1, characterized in that, Each of the absorbing units includes a loss-absorbing thin film, a loss-dielectric layer and an intermediate metal layer stacked from top to bottom. The resonant structure is a square conductive ring in the form of a metal pattern etched on the loss-absorbing thin film. The power combining network dielectric layer is disposed on the back side of the intermediate metal layer.

3. The circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 1, characterized in that, The characteristic impedance of the impedance transformation transmission line segment is 70-75Ω and the line width W5 is 0.9-1.2mm; the characteristic impedance of the trunk transmission line segment is 50Ω and the line width W4 is 1.8-2.2mm; and the line width W3 of the port transition line segment is 0.6-1.0mm.

4. A circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 2, characterized in that, The multiple absorbing units are arranged in a 4×4 array periodically, with a periodic side length P1 of 9–11 mm; the thickness H1 of the loss dielectric layer is the same as the thickness H5 of the power combining network dielectric layer, and H1 = H5 = 1.4–1.7 mm; the thickness H2 of the loss absorption film, the thickness H3 of the intermediate metal layer, and the thickness H4 of the power combining module are the same, and H2 = H3 = H4 = 0.03–0.04 mm; the length Px and width Py of the conductive ring are both 8.5–8.8 mm; the linewidth Wx of the conductive ring in the x-direction is 3–3.5 mm, and the linewidth Wy in the y-direction is 1.4–1.7 mm; the gap width Wc of the capacitive open trench is 1–1.6 mm; the opening width Wr of the resistive open trench is 0.2–0.6 mm; the radius r of the metallized via is 0.3–0.6 mm; and the capacitive element is a surface-mount capacitor with a capacitance of 0.1–0.3 pF.

5. A circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 2, characterized in that, The rectifier module sequentially includes an impedance matching section, a rectification section, and a filtering section disposed on the dielectric substrate. The impedance matching section includes a first microstrip line stub and a second microstrip line stub disposed on the first connection section. The rectification section adopts a voltage doubler rectifier circuit. The rectification section includes a DC filter capacitor and a Schottky diode disposed on the second connection section. The first connection section is electrically connected to the second connection section via the DC filter capacitor. The filtering section includes a sector-shaped harmonic suppression unit disposed on the third connection section, a filter capacitor, a grounding via, and a load connection terminal. The sector-shaped harmonic suppression unit cooperates with the grounding via to suppress harmonic components. The load connection terminal is used to lead out the rectified DC output.

6. A circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 5, characterized in that, The rectifier module has a linewidth W of 2.7–2.9 mm; the first microstrip stub has a width W1 of 1.8–2 mm and a length L8 of 11–12 mm; the second microstrip stub has a width W2 of 2.1–2.3 mm and a length L9 of 13–14 mm; the distance between the first and second microstrip stubs is L2 = 9.8–10.1 mm; and the distance between the second microstrip stub and the DC filter capacitor is L3 = 6.9–7.1 mm. mm; the distance L4 between the DC filter capacitor and the Schottky diode is 8.8-9 mm; the width Wi of the sector-shaped harmonic suppression unit is 1.5-1.7 mm, the length L is 3.9-4.1 mm, and the rotation angle A is 65-75°; the radius of the grounding via is equal to the radius of the metallized via; the capacitance value of the DC filter capacitor is 680 nF, the capacitance value of the filter capacitor is 470 nF, and the model of the Schottky diode is HSMS286C.

7. A circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 5, characterized in that, The loss dielectric layer, the power combining network dielectric layer, and the dielectric substrate are all made of FR4 dielectric material, with a relative permittivity of 4.3 and a loss tangent of 0.

025.

8. A circularly polarized polarization-selective wireless energy harvesting rectifier according to claim 1, characterized in that, The power combining module and the rectifier module are connected via a coaxial connector.

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