Polarization reconfigurable circularly polarized antenna designed by using artificial surface plasmon structure

Abstract

The invention discloses a polarization reconfigurable circularly polarized antenna designed by using an artificial surface plasmon structure, which is etched on an upper metal layer of a single-layer dielectric plate, and comprises four rectangular radiation patches which are distributed in a central symmetry manner and respectively correspond to a first feed port, a second feed port, a third feed port and a fourth feed port; the two artificial surface plasmon structures are in a bent line shape, and the two ends of each artificial surface plasmon structure are electrically connected to the two adjacent rectangular radiation patches respectively, so that a phase delay path is formed between the adjacent feed ports; the one-to-four microstrip feed network comprises a main feed line and four branch feed lines led out from a node of the main feed line; the four radio frequency switches are respectively connected in series with the four branch feed lines and the four corresponding rectangular radiation patches; and by controlling the alternate connection and disconnection of two groups of diagonal switches in the four radio frequency switches, radio frequency signals are fed in through different feed ports and are transmitted through the artificial surface plasmon structure, so that phase delay is realized to output circularly polarized waves.

Description

Technical Field

[0001] This invention belongs to the technical field of wireless communication and antenna design, specifically relating to a polarization-reconfigurable circularly polarized antenna designed using artificial surface plasmon structures. Background Technology

[0002] Circularly polarized antennas possess irreplaceable advantages in the field of wireless communication due to their unique polarization characteristics. On the one hand, circularly polarized antennas can effectively reduce signal attenuation caused by polarization mismatch, significantly improving the flexibility of transmitters and receivers in directional adjustment; on the other hand, they can significantly suppress multipath interference and enhance the stability of signal transmission. Therefore, they have been widely used in key scenarios such as satellite communication, radio frequency identification (RFID), wireless local area networks (WLAN), and global positioning systems (GPS), and have received continuous attention from academia and industry.

[0003] The core bottleneck in realizing circularly polarized antennas lies in the fact that they typically require a 90° phase delay loop and a coaxial feeding mechanism, necessitating the use of multilayer dielectric substrate structures. This not only increases the complexity and cost of the fabrication process but also makes it difficult to meet the miniaturization and lightweight requirements of modern communication equipment. In recent years, crossed dipole structures have become a research hotspot in circularly polarized (CP) radiation technology due to their simple structure, stable polarization characteristics, and ease of integration. However, there are still key unresolved contradictions in the research of circularly polarized antennas: First, it is difficult to balance structural compactness and broadband performance. For example, the zigzag loop UHF RFID antenna proposed by some scholars has an impedance bandwidth of only 2.9%, which is far from meeting the needs of modern broadband communication. Second, the polarization switching mechanism of reconfigurable circularly polarized antennas has defects. Existing solutions mostly rely on the parameter adjustment of complex feeding networks, resulting in slow switching response speed, poor stability, and insufficient phase modulation accuracy. Third, the integration of core radiating units such as artificial surface plasmon structures and crossed dipoles needs to be optimized. The lack of coordinated design between phase modulation and structural compactness in existing designs limits the practical application scenarios of the antennas.

[0004] Based on this, the research paradigm in this field is shifting from "phase modulation relying on external feeding networks" to "self-phase adjustment through the optimization of the intrinsic structure of the radiating unit." For example, by precisely controlling the admittance characteristics through orthogonally arranged dipoles, an intrinsic generation of a 90° phase difference has been achieved, marking the development of broadband circular polarization technology towards a fusion of structural simplification and performance optimization. However, how to achieve the synergistic design of compact structure, broadband circular polarization radiation, and stable polarization switching on a single-layer substrate remains a technical challenge that current technologies have not yet overcome. Summary of the Invention

[0005] The present invention aims to at least partially solve one of the technical problems existing in the related art.

[0006] The purpose of this invention is to provide a polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure. By integrating a specific structure on a single-layer dielectric substrate, a compact and high-performance polarization-reconfigurable circularly polarized antenna design is achieved, solving the problems of complex structure, high cost, and inflexible polarization switching of existing circularly polarized antennas.

[0007] To achieve the above objectives, the present invention provides a polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure, comprising a single-layer dielectric substrate, on which four rectangular radiating patches, two artificial surface plasmon structures, a one-to-four microstrip feed network, and four radio frequency switches are etched on the upper metal layer of the single-layer dielectric substrate.

[0008] The four rectangular radiating patches are centrally symmetrically distributed and correspond to the first to fourth power supply ports, respectively.

[0009] Both segments of the artificial surface plasmon structure are bent lines, and the two ends of each segment of the artificial surface plasmon structure are electrically connected to two adjacent rectangular radiating patches to form a phase delay path between the adjacent feed ports.

[0010] The one-to-four microstrip feed network includes a main feeder and four branch feeders extending from the main feeder node, and the four branch feeders extend to the vicinity of the four rectangular radiating patches respectively.

[0011] The four radio frequency switches are connected in series with the four branch feed lines and the corresponding four rectangular radiating patches, respectively, to independently control the on / off state of each branch feed line.

[0012] By controlling the alternating on and off of two sets of diagonal switches among the four RF switches, the RF signal is fed in through different feed ports and transmitted through the artificial surface plasmon structure, thereby achieving phase delay to output a circularly polarized wave.

[0013] A further preferred technical solution of the present invention is that the two artificial surface plasmon structures have the same structure, both being a five-segment folded continuous structure, which is composed of five straight metal segments connected end to end in sequence, with adjacent metal segments folded at 90° right angles to form a symmetrical sawtooth structure.

[0014] Each of the aforementioned straight metal segments is 7.8 mm long, 0.7 mm wide, and has a corner radius of 0.1 mm at the fold.

[0015] Preferably, the four rectangular radiating patches each have a side length of 21.6 mm, and the spacing between adjacent rectangular radiating patches is 0.3 mm.

[0016] Preferably, the one-to-four microstrip feed network is a microstrip line structure with a characteristic impedance of 50Ω, the main feed line has a width of 0.75mm and a length of 18mm, and the end of the main feed line is reserved with an SMA connector welding position and fixed with a nut.

[0017] Preferably, all four radio frequency switches are PIN diodes with an operating frequency range of 1-3GHz, an on-resistance of ≤1Ω, an off-resistance of ≤0.5pF, and the positive and negative poles of the four PIN diodes are aligned.

[0018] Preferably, the two artificial surface plasmon structures are respectively a first artificial surface plasmon structure and a second artificial surface plasmon structure, and the four rectangular radiating patches are respectively a first rectangular radiating patch, a second rectangular radiating patch, a third rectangular radiating patch and a fourth rectangular radiating patch, corresponding to the first feed port, the second feed port, the third feed port and the fourth feed port, respectively.

[0019] The two artificial surface plasmonic structures and the four rectangular radiating patches are symmetrically arranged about the central axis of the one-to-four microstrip feed network; wherein, the first artificial surface plasmonic structure is connected to the first rectangular radiating patch at its head end and to the second rectangular radiating patch at its tail end; the second artificial surface plasmonic structure is connected to the fourth rectangular radiating patch at its head end and to the third rectangular radiating patch at its tail end.

[0020] Preferably, the four RF switches are a first RF switch, a second RF switch, a third RF switch, and a fourth RF switch; the four RF switches are connected in series in the connection paths of the four branch feed lines and the corresponding feed ports, wherein the first RF switch is connected in series in the connection path of the second feed port, the second RF switch is connected in series in the connection path of the first feed port, the third RF switch is connected in series in the connection path of the third feed port, and the fourth RF switch is connected in series in the connection path of the fourth feed port.

[0021] Preferably, the first switch group is composed of the second RF switch and the fourth RF switch, and the second switch group is composed of the first RF switch and the third RF switch.

[0022] When the first switch group is turned on and the second switch group is turned off, the radio frequency signal is fed in from the first feed port and the fourth feed port, and transmitted to the second feed port and the third feed port through two artificial surface plasmon structures, and the antenna radiates a left-hand circularly polarized wave; when the second switch group is turned on and the first switch group is turned off, the radio frequency signal is fed in from the second feed port and the third feed port, and transmitted to the first feed port and the fourth feed port through two artificial surface plasmon structures, and the antenna radiates a right-hand circularly polarized wave.

[0023] Preferably, the single-layer dielectric substrate is a Rogers 5880 substrate with a dielectric constant ε. r =2.2, loss tangent tanδ=0.0009.

[0024] Preferably, the single-layer dielectric substrate has dimensions of 55mm × 55mm and a thickness of 2mm; the antenna's S11 parameter is ≤ -10dB in the 1.39-1.61GHz frequency band, and the axial ratio AR is ≤ 3dB and the axial ratio fluctuation is ≤ 0.5dB in the 1.40-1.58GHz frequency band.

[0025] Beneficial effects: This invention integrates the core functional structure through a single-layer dielectric substrate, eliminating the need for a complex phase-shifting network. It achieves a compact structure while ensuring stable circular polarization performance, thus solving the technical problems of complex structure and insufficient polarization switching flexibility of traditional circular polarization antennas. Attached Figure Description

[0026] Figure 1 This is a top view of the polarization-reconfigurable circularly polarized antenna designed using artificial surface plasmon structures according to the present invention.

[0027] Figure 2 This is a side view of the polarization-reconfigurable circularly polarized antenna designed using artificial surface plasmon structures according to the present invention.

[0028] Figure 3 This is a top view of the rectangular radial patch in this invention;

[0029] Figure 4 This is a top view of the artificial surface plasmon structure in this invention;

[0030] Figure 5 The simulated response diagram of the S11 parameters of the polarization reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure in the embodiment is shown.

[0031] Figure 6 The AR parameter simulation response diagram of the polarization reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure in the embodiment is shown.

[0032] Figure 7 Simulated gain response diagrams of the xoz and yoz planes of the left-hand and right-hand circularly polarized antennas designed using artificial surface plasmon structures.

[0033] In the figure, 101-first artificial surface plasmon structure, 102-second artificial surface plasmon structure, 103-first radio frequency switch, 104-second radio frequency switch, 105-third radio frequency switch, 106-fourth radio frequency switch, 107-first rectangular radiating patch, 108-first rectangular radiating patch, 109-first rectangular radiating patch, 110-first rectangular radiating patch, 201-single-layer dielectric substrate. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, embodiments of this invention, and should not be construed as limiting the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] The following is combined Figures 1-6 This invention describes a polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure.

[0036] Example 1: This example provides a polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure.

[0037] This is achieved by etching the upper metal layer of a single-layer dielectric substrate 201, eliminating the need for drilling processes. All functional structures are integrated through a single-layer substrate, effectively ensuring the consistency of the antenna structure and the feasibility of fabrication, and reducing the complexity of fabrication.

[0038] The upper metal layer has complete functional components, such as Figure 1 As shown, it includes: four rectangular radiating patches, two artificial surface plasmon structures, a one-to-four microstrip feed network, and four radio frequency switches.

[0039] The four rectangular radiating patches are centrally symmetrically distributed and correspond to the first to fourth power supply ports, respectively.

[0040] Both segments of the artificial surface plasmon structure are bent lines, and the two ends of each segment of the artificial surface plasmon structure are electrically connected to two adjacent rectangular radiating patches to form a phase delay path between the adjacent feed ports.

[0041] The one-to-four microstrip feed network includes a main feeder and four branch feeders extending from the main feeder node, and the four branch feeders extend to the vicinity of the four rectangular radiating patches respectively.

[0042] The four radio frequency switches are connected in series with the four branch feed lines and the corresponding four rectangular radiating patches, respectively, to independently control the on / off state of each branch feed line.

[0043] By controlling the alternating on and off of two sets of diagonal switches among the four RF switches, the RF signal is fed in through different feed ports and transmitted through the artificial surface plasmon structure, thereby achieving phase delay to output a circularly polarized wave.

[0044] The following is a detailed description of each part of the antenna:

[0045] Single-layer dielectric substrate 201, such as Figure 2 As shown, the Rogers 5880 substrate was selected, which has stable dielectric properties (dielectric constant ε). r =2.2, loss tangent tanδ=0.0009), low signal transmission loss in the 1~2GHz operating frequency band, high mechanical strength, and easy control of processing precision, fully meeting the performance requirements of this antenna. The overall size of the substrate is 55mm×55mm, and the thickness is 2mm, providing stable support for all upper metal functional structures.

[0046] The two artificial surface plasmon structures are the first artificial surface plasmon structure 101 and the second artificial surface plasmon structure 102, respectively. The four rectangular radiating patches are the first rectangular radiating patch 107, the second rectangular radiating patch 108, the third rectangular radiating patch 109 and the fourth rectangular radiating patch 110, respectively, corresponding to the first feed port, the second feed port, the third feed port and the fourth feed port; the four radio frequency switches are the first radio frequency switch 103, the second radio frequency switch 104, the third radio frequency switch 105 and the fourth radio frequency switch 106.

[0047] The 1-to-4 microstrip feed network is a microstrip line structure with a characteristic impedance of 50Ω to ensure impedance matching with the SMA connector. The main feed line has a width of 0.75mm and a length of 18mm. The end of the main feed line has a reserved SMA connector welding position and is fixed with a nut for connecting external circuits to realize signal input and transmission. After welding, it is fixed to the edge of the dielectric board with a nut to ensure the mechanical stability and electrical reliability of the feed connection.

[0048] Four rectangular radiating patches as follows Figure 3 As shown, the side length of each rectangular radiating patch is 21.6 mm, and the spacing between adjacent patches is 0.3 mm. This avoids excessive electromagnetic coupling between adjacent patches while providing sufficient installation space for the artificial surface plasmon structure. The two sections of the artificial surface plasmon structure have the same structure, as shown... Figure 4As shown, all five segments are folded continuous structures, consisting of five straight metal segments connected end-to-end. Adjacent metal segments are folded at 90° right angles to form a symmetrical sawtooth structure. Each straight metal segment is 7.8mm long and 0.7mm wide, with a 0.1mm radius at the fold to prevent structural damage caused by stress concentration. All four RF switches are PIN diodes with an operating frequency range of 1-3GHz, on-resistance ≤1Ω, and cutoff capacitance ≤0.5pF. The positive and negative terminals of the four PIN diodes are aligned.

[0049] The first artificial surface plasmon structure 101 is connected at its head to the first rectangular radiating patch 107, and at its tail to the second rectangular radiating patch 108; the second artificial surface plasmon structure 102 is connected at its head to the fourth rectangular radiating patch 110, and at its tail to the third rectangular radiating patch 109. With no additional solder joints, signal transmission loss is reduced while improving the overall structural integrity.

[0050] Four radio frequency (RF) switches are connected in series on the connection paths of four branch feed lines and their corresponding feed ports. Specifically, the first RF switch 103 is connected in series to the connection path of the second feed port, the second RF switch 104 is connected in series to the connection path of the first feed port, the third RF switch 105 is connected in series to the connection path of the third feed port, and the fourth RF switch 106 is connected in series to the connection path of the fourth feed port. The second RF switch 104 and the fourth RF switch 106 form a first switch group, and the first RF switch 103 and the third RF switch 105 form a second switch group. When the first switch group is on and the second switch group is off, the RF signal is fed into the first and fourth feed ports, transmitted through two artificial surface plasmon structures to the second and third feed ports, and the antenna radiates a left-hand circularly polarized wave. When the second switch group is on and the first switch group is off, the RF signal is fed into the second and third feed ports, transmitted through two artificial surface plasmon structures to the first and fourth feed ports, and the antenna radiates a right-hand circularly polarized wave.

[0051] In this embodiment, a full-wave simulation model of the polarization reconfigurable circularly polarized antenna was established in the electromagnetic simulation software HFSS19.0. The simulation settings are as follows: the boundary condition adopts a radiating boundary, the excitation method is waveport excitation (matching impedance 50Ω), the simulation frequency range is 0.5~3.0GHz, the frequency step is 0.01GHz, and the convergence criterion is set to -60dB to ensure simulation accuracy.

[0052] The simulation results are as follows:

[0053] 1. S11 parameter response (e.g.) Figure 5As shown in the figure): In the 1.39~1.61GHz frequency band, the S11 parameter ≤ -10dB, indicating that the antenna input impedance is well matched with the feed line, the reflection loss is small, and the signal transmission efficiency is high.

[0054] 2. AR parameter response (e.g.) Figure 6 As shown): Within the effective operating passband of 1.40~1.58GHz, the axial ratio AR≤3dB, which meets the core performance requirements of circularly polarized antennas (axial ratio ≤3dB is the effective frequency band of circular polarization), and the axial ratio fluctuation ≤0.5dB, indicating that the antenna has stable circular polarization characteristics, high polarization purity, and can effectively achieve stable switching between left-hand and right-hand circular polarization.

[0055] 3. For example Figure 7 The figure shows the simulated gain response diagrams of the xoz and yoz planes of the left-hand and right-hand circularly polarized antennas designed using artificial surface plasmon structures. The maximum gain of the pattern is approximately 2.5 dB, and the beamwidth at 3 dB gain is approximately 60°. The maximum gain of the left-hand and right-hand circularly polarized antennas is consistent, both close to 2.5 dB, and their curves show a high degree of overlap in the high-gain region.

[0056] In summary, the polarization-reconfigurable circularly polarized antenna of this embodiment integrates all functional structures through a Rogers5880 single-layer dielectric substrate, resulting in a compact structure, simple fabrication, and excellent broadband matching performance and stable circular polarization characteristics. It is fully adaptable to the application requirements of modern wireless communication scenarios such as satellite communication, radio frequency identification, and wireless local area networks.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure, comprising a single-layer dielectric substrate, characterized in that, The upper metal layer of the single-layer dielectric substrate is etched with four rectangular radiating patches, two artificial surface plasmon structures, a one-to-four microstrip feed network, and four radio frequency switches. The four rectangular radiating patches are centrally symmetrically distributed and correspond to the first to fourth power supply ports, respectively. Both segments of the artificial surface plasmon structure are bent lines, and the two ends of each segment of the artificial surface plasmon structure are electrically connected to two adjacent rectangular radiating patches to form a phase delay path between the adjacent feed ports. The one-to-four microstrip feed network includes a main feeder and four branch feeders extending from the main feeder node, and the four branch feeders extend to the vicinity of the four rectangular radiating patches respectively. The four radio frequency switches are connected in series with the four branch feed lines and the corresponding four rectangular radiating patches, respectively, to independently control the on / off state of each branch feed line. By controlling the alternating on and off of two sets of diagonal switches among the four RF switches, the RF signal is fed in through different feed ports and transmitted through the artificial surface plasmon structure, thereby achieving phase delay to output a circularly polarized wave.

2. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 1, characterized in that, The two artificial surface plasmon structures have the same structure, both being a five-segment folded continuous structure, consisting of five straight metal segments connected end to end, with adjacent metal segments folded at 90° right angles to form a symmetrical sawtooth structure. Each of the aforementioned straight metal segments is 7.8 mm long, 0.7 mm wide, and has a corner radius of 0.1 mm at the fold.

3. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 1, characterized in that, The four rectangular radiating patches each have a side length of 21.6 mm, and the spacing between adjacent rectangular radiating patches is 0.3 mm.

4. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 1, characterized in that, The one-to-four microstrip feed network is a microstrip line structure with a characteristic impedance of 50Ω. The main feed line has a width of 0.75mm and a length of 18mm. The end of the main feed line is reserved with an SMA connector welding position and fixed with a nut.

5. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 1, characterized in that, All four RF switches are PIN diodes with an operating frequency range of 1-3GHz, on-resistance ≤1Ω, and cut-off capacitance ≤0.5pF. The positive and negative terminals of the four PIN diodes are aligned.

6. The polarization-reconfigurable circularly polarized antenna designed using artificial surface plasmon structures according to any one of claims 1-5, characterized in that, The two artificial surface plasmon structures are respectively the first artificial surface plasmon structure and the second artificial surface plasmon structure, and the four rectangular radiating patches are respectively the first rectangular radiating patch, the second rectangular radiating patch, the third rectangular radiating patch and the fourth rectangular radiating patch, which correspond to the first feed port, the second feed port, the third feed port and the fourth feed port, respectively. The two artificial surface plasmonic structures and the four rectangular radiating patches are symmetrically arranged about the central axis of the one-to-four microstrip feed network; wherein, the first artificial surface plasmonic structure is connected to the first rectangular radiating patch at its head end and to the second rectangular radiating patch at its tail end; the second artificial surface plasmonic structure is connected to the fourth rectangular radiating patch at its head end and to the third rectangular radiating patch at its tail end.

7. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 6, characterized in that, The four radio frequency switches are a first radio frequency switch, a second radio frequency switch, a third radio frequency switch, and a fourth radio frequency switch. The four radio frequency switches are connected in series in the connection paths of the four branch feed lines and the corresponding feed ports. Specifically, the first radio frequency switch is connected in series in the connection path of the second feed port, the second radio frequency switch is connected in series in the connection path of the first feed port, the third radio frequency switch is connected in series in the connection path of the third feed port, and the fourth radio frequency switch is connected in series in the connection path of the fourth feed port.

8. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 7, characterized in that, The first switch group consists of the second radio frequency switch and the fourth radio frequency switch, and the second switch group consists of the first radio frequency switch and the third radio frequency switch; When the first switch group is turned on and the second switch group is turned off, the radio frequency signal is fed in from the first feed port and the fourth feed port, and transmitted to the second feed port and the third feed port through two artificial surface plasmon structures, and the antenna radiates a left-hand circularly polarized wave; when the second switch group is turned on and the first switch group is turned off, the radio frequency signal is fed in from the second feed port and the third feed port, and transmitted to the first feed port and the fourth feed port through two artificial surface plasmon structures, and the antenna radiates a right-hand circularly polarized wave.

9. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 1, characterized in that, The single-layer dielectric substrate is a Rogers 5880 substrate with a dielectric constant ε. r =2.2, loss tangent tanδ=0.0009.

10. The polarization-reconfigurable circularly polarized antenna designed using an artificial surface plasmon structure according to claim 9, characterized in that, The single-layer dielectric substrate has dimensions of 55mm × 55mm and a thickness of 2mm; the antenna's S11 parameter is ≤ -10dB in the 1.39-1.61GHz frequency band, and its axial ratio AR is ≤ 3dB and its axial ratio fluctuation is ≤ 0.5dB in the 1.40-1.58GHz frequency band.

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