Dual-band dual-mode dual-polarized antenna based on pattern modulation and application

Abstract

The application provides a dual-frequency dual-mode dual-polarized antenna based on mode modulation and application, and belongs to the technical field of antennas. The antenna is composed of a flexible dielectric substrate, a circular metal radiation patch, a metal ground and a feed point. The key innovation lies in a plurality of groove structure groups etched on the radiation patch, including a center groove, a first groove group, a second groove group, a T-shaped groove group and a circular groove group. The groove structure groups are designed to be able to excite mode and mode, so that the antenna realizes directional circular polarization mode at a 2.4 GHz frequency band and omnidirectional linear polarization mode at a 5.7 GHz frequency band. The application adopts the above-mentioned dual-frequency dual-mode dual-polarized antenna based on mode modulation and application, and through optimization of groove parameters and feed point positions, realizes efficient work of dual-frequency bands, solves polarization mismatch problems and realizes intelligent adaptation of dual modes.

Description

Technical Field

[0001] This invention relates to the field of antennas, and in particular to a dual-frequency, dual-mode, dual-polarization antenna based on mode modulation and its applications. Background Technology

[0002] With the rapid development of Wireless Body Area Network (WBAN) technology, wearable devices have become multifunctional intelligent systems integrating health monitoring, human-computer interaction, and environmental perception. Depending on the communication scenario, WBAN mainly includes the following modes:

[0003] Surface communication: requires omnidirectional radiation mode to cover the curved surface of the human body, and mainly operates in the 2.4GHz ISM band.

[0004] External communication: requires directional radiation mode to achieve efficient far-field transmission, and often uses frequency bands such as 5.7GHz ISM.

[0005] However, existing wearable antenna technologies suitable for WBAN have significant shortcomings in meeting the above-mentioned requirements for multiple scenarios, as follows:

[0006] Poor polarization matching performance: Traditional linearly polarized antennas are prone to severe signal attenuation due to polarization mismatch when the human body is in motion, resulting in low link reliability.

[0007] Single radiation mode: Existing designs make it difficult to integrate omnidirectional and directional dual modes in the same structure, forcing devices to adopt multi-antenna schemes, resulting in increased system size, power consumption and cost.

[0008] Multi-band performance is insufficient: existing antennas are mostly focused on a single frequency band and cannot effectively cover the two core WBAN frequency bands of 2.4GHz and 5.7GHz at the same time; some dual-band designs also have problems such as narrow bandwidth and poor impedance matching.

[0009] Poor wearability compatibility: Antennas using rigid substrates such as FR-4 have poor flexibility and insufficient fit and comfort; while some flexible antennas use textile materials, they have problems such as high specific absorption rate (SAR) and severe deterioration of electrical performance after bending, making it difficult to meet the requirements for long-term and safe wear.

[0010] To address these issues, the industry has explored various dual-polarization technology approaches, but limitations still exist:

[0011] Crossed dipole structure: can achieve dual polarization, but has a high profile and is difficult to integrate;

[0012] Microstrip patch: can achieve dual polarization through orthogonal feeding, but has a narrow operating bandwidth;

[0013] Metasurface / reconfigurable technology: can extend performance, but has complex structure and poor compatibility with flexible design.

[0014] Therefore, the core challenge of current technology lies in how to design a wearable antenna that can simultaneously achieve dual-band operation, independent polarization control, adaptive switching of omnidirectional / directional modes, and meet human safety specifications (SAR < 1.6 W / kg) under the strict constraints of low profile and flexible substrate. Summary of the Invention

[0015] The purpose of this invention is to provide a dual-band, dual-mode, dual-polarization antenna based on mode modulation and its application, which solves the shortcomings of existing wearable antennas in various application scenarios, such as poor polarization matching, single radiation mode, insufficient multi-band performance, and poor wearability compatibility. Through an innovative slot structure design, it achieves efficient dual-band operation, polarization mismatch resolution, and intelligent dual-mode adaptation, while ensuring antenna flexibility, wearability comfort, and performance stability, thus providing a better communication solution for wearable devices.

[0016] To achieve the above objectives, the present invention provides a dual-band, dual-mode, dual-polarization antenna based on mode modulation, comprising a flexible dielectric substrate, a circular metal radiating patch, a metal ground, and a feed point. The upper surface of the flexible dielectric substrate is covered with the circular metal radiating patch, and the lower surface is covered with the metal ground. The circular metal radiating patch is etched with multiple slot structures, including a central slot, a first slot group, a second slot group, a T-shaped slot group, and a circular slot group. The central slot is an inclined rectangular slot that penetrates the center of the circular metal radiating patch. The first slot group is symmetrically arranged along the y-axis direction of the circular metal radiating patch, and the second slot group is symmetrically arranged along the x-axis direction of the circular metal radiating patch. The T-shaped slot group includes four T-shaped slots, which are centrally symmetrically distributed with respect to the center of the circular metal radiating patch. The circular slot group includes four first circular slots, which are located on the same circumference with respect to the center of the circular metal radiating patch and are centrally symmetrically distributed.

[0017] The slotted structure is configured to excite the circular metallic radiation patch. Pattern and The mode enables the antenna to operate in directional circular polarization mode in the 2.4 GHz band and omnidirectional linear polarization mode in the 5.7 GHz band.

[0018] Preferably, the central groove is set along the -45° direction of the circular metal radiating patch, with a length of 14.5-15.5 mm and a width of 2.5-3.5 mm.

[0019] Preferably, the first slot group includes two slot units, each slot unit including a first rectangular slot and a second circular slot connected to the end of the first rectangular slot. The length of each first rectangular slot is 9-10 mm and the width is 1.8-2.2 mm, and the radius of each second circular slot is 0.8-1.2 mm.

[0020] Preferably, the second slot group includes four second rectangular slots, each second rectangular slot having a length of 12.6-13.4 mm and a width of 1-1.4 mm.

[0021] Preferably, the four T-shaped grooves are located at 45°, 135°, 225° and 315° of the circular metal radiating patch, respectively. Each T-shaped groove is formed by two orthogonal rectangles with lengths of 7.5-8mm and 3.5-4.5mm respectively and widths of 0.3-0.7mm.

[0022] Each T-shaped groove has an additional rectangular groove etched along the angle bisector on both the left and right sides, with a length of 3.5-4.5 mm and a width of 0.3-0.7 mm.

[0023] Preferably, the four first circular grooves of the circular groove group are located on a circumference with a radius of 11-12 mm and are evenly distributed at 45°, 135°, 225° and 315° positions, and the radius of each first circular groove is 1-1.5 mm.

[0024] Preferably, the power supply point is located on a circular metal radiating patch and is offset from its center, with a distance of 8.3-8.7 mm from the center of the circular metal radiating patch and a radius of 27.5-28 mm.

[0025] Preferably, the flexible dielectric substrate is a felt material substrate with a dielectric constant of 1.2, a loss tangent of 0.02, a thickness of 2 mm, and a radius of 33-35 mm.

[0026] The present invention also provides a wearable device, including the dual-band dual-mode dual-polarized wearable antenna as described above.

[0027] The present invention also provides a wireless communication system, including the dual-band dual-mode dual-polarized wearable antenna as described above.

[0028] Therefore, the present invention employs the above-mentioned mode-modulation-based dual-frequency dual-mode dual-polarization antenna and its application, and the beneficial technical effects are as follows:

[0029] (1) This invention achieves efficient operation in two core ISM bands, 2.4 GHz and 5.7 GHz, with performance decoupling between the two bands and low mutual interference. High gain is achieved in both the 2.4 GHz band (directional mode) and the 5.7 GHz band (omnidirectional mode), and the return loss S11 in both bands meets the requirements of engineering applications. The impedance matching requirement of -10dB far exceeds that of traditional wearable antennas, providing a solid foundation for high-speed data transmission.

[0030] (2) This invention fundamentally solves the polarization mismatch problem caused by changes in human posture in wearable devices by using left-hand circular polarization radiation in the 2.4GHz band, significantly enhancing the stability of the link and its resistance to multipath interference. Omnidirectional / directional dual-mode intelligent adaptation to surface / external communication scenarios is achieved, and a single antenna can meet the needs of different communication distances and coverage areas, solving the pain point of poor adaptability of single-mode antennas in various scenarios.

[0031] (3) The present invention adopts an integrated topology structure of "single patch - multiple slots", which eliminates the need for a complex feed network or multiple physical antennas, and achieves a high degree of integration of dual frequency, dual mode and dual polarization. The antenna volume is reduced by more than 60% compared with the traditional solution. Based on the felt flexible substrate and silver-plated conductive cloth, the antenna has excellent flexibility and skin affinity, ensuring wearing comfort. At the same time, the hot pressing process ensures the structural reliability and performance stability under bending environment.

[0032] (4) The low dielectric constant flexible substrate combined with the optimized radiation mode effectively reduces the electromagnetic coupling between the antenna and human tissue, and strictly controls the specific absorption rate (SAR) within the safe limit (<1.6W / kg), meeting the health and safety requirements for long-term wear. The high gain characteristic means that the device's transmission power can be reduced accordingly under the same communication quality, thereby helping to extend the battery life of wearable devices. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the dual-frequency dual-mode dual-polarization antenna based on mode modulation according to the present invention;

[0034] Figure 2 This is the normalized antenna radiation pattern in the 5.7GHz xoz plane of this invention;

[0035] Figure 3 This is the normalized antenna radiation pattern in the 2.4GHz xoz plane of this invention;

[0036] Figure 4 This is the normalized antenna radiation pattern in the 5.7GHz xoy plane of this invention;

[0037] Figure 5 This is a graph showing the return loss S11 of the present invention as a function of frequency.

[0038] Figure 6 Comparison of return loss S11 curves at different feed point locations;

[0039] Figure 7 The effect of different center groove lengths on S11;

[0040] Figure 8 The effect of different center groove widths on S11;

[0041] Figure 9 For different lengths of the second rectangular groove The impact of mode S11;

[0042] Figure 10 For different lengths of the first rectangular slot The impact of mode S11;

[0043] Figure 11 For different first rectangular slot widths The impact of mode S11.

[0044] Figure Labels

[0045] 1. Flexible dielectric substrate; 2. Circular metal radiating patch; 3. Central groove; 4. T-shaped groove; 5. First circular groove; 6. First rectangular groove; 7. Second circular groove; 8. Second rectangular groove; 9. Additional rectangular groove; 10. Feed point. Detailed Implementation

[0046] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0048] Example 1

[0049] This invention provides a dual-frequency, dual-mode, dual-polarization antenna based on mode modulation, the structure of which is as follows: Figure 1 As shown, the antenna adopts a double-layer structure of "flexible substrate-conductive cloth radiating layer": the flexible dielectric substrate 1 is made of felt material with a dielectric constant of 1.2 and a loss tangent of 0.02, with a thickness of 2mm and a radius of 34mm; the radiating body and the metal ground both use silver-plated conductive cloth with a thickness of 0.1mm, which is tightly bonded to the substrate through a hot pressing process to ensure conductivity and bending durability.

[0050] The radiating body is a circular metal radiating patch 2 with a radius of 27.9 mm. Multiple sets of slot structures are etched on the circular metal radiating patch 2, including:

[0051] (1) Center slot 3: An inclined rectangular slot with a length of 15mm and a width of 3mm is set along the -45° direction of the patch. It is used to introduce geometric perturbations to excite circular polarization.

[0052] (2) First slot group: Two slot units symmetrically arranged along the y-axis direction of the circular metal radiation patch 2. Each slot unit includes a first rectangular slot 6 with a length of 9.5 mm and a width of 2 mm and a second circular slot 7 with a radius of 1 mm at its end.

[0053] (3) Second slot group: Four second rectangular slots 8 are symmetrically arranged along the x-axis direction of the circular metal radiating patch 2, each 13mm long and 1.2mm wide, for impedance matching and frequency adjustment.

[0054] (4) T-slot group: Four T-slots 4 located at 45°, 135°, 225° and 315°, each consisting of two orthogonal rectangles with a length of 7.75mm and a width of 4mm and 0.5mm respectively. An additional rectangular slot 9 with a length of 4mm and a width of 0.5mm is etched on each side of the angle bisector of each T-slot 4 to extend the current path and reduce the resonant frequency.

[0055] (5) Circular slot group: four first circular slots 5, each with a radius of 1.5 mm, are located on a circumference with a radius of 12 mm and are evenly distributed at 45°, 135°, 225° and 315°. They are used to optimize impedance matching.

[0056] Antenna through 50 SMA connector power supply, with power supply point 10 offset from the center of the circular metal radiating patch by 8.5mm to ensure dual-band impedance matching.

[0057] Operating mode and frequency band characteristics.

[0058] 2.4GHz band (directional circular polarization): excited by tilted rectangular slots The mode and its degenerate modes form a left-handed circular polarization. The surface current is distributed along the diameter of the patch, and the tilted rectangular slot rotates the current path, generating orthogonal electric field components with a 90° phase difference. The radiation pattern is directional, as shown below. Figure 3 As shown, the radiation pattern exhibits directional radiation characteristics, with the maximum radiation direction perpendicular to the patch plane, making it suitable for long-distance external communication.

[0059] 5.7GHz band (omnidirectional linear polarization): utilizing In this mode, the surface current is distributed radially, and the electric field is along the z-axis, forming linear polarization. For example... Figure 2 As shown, the radiation pattern in the xoz plane exhibits a double-lobed radiation characteristic, with the radiated energy mainly concentrated in the ±z directions, reflecting the directional radiation trend of this frequency band in the xoz plane. By extending the current path through the second rectangular slot 8 and the T-shaped slot group along the x-axis, the resonant frequency was precisely tuned to 5.7 GHz. The radiation pattern is omnidirectional, as shown... Figure 4 As shown, the radiation pattern of the xoy plane is relatively uniform within a 360° range, with only small fluctuations and no obvious "concentrated" main beam, exhibiting omnidirectional characteristics, which is suitable for close-range interaction on the body surface.

[0060] Parameter optimization and performance analysis.

[0061] Feed point 10 location: Select =8.5mm, to balance and Impedance matching of modes. When it increases, The resonant frequency decreases and the matching deteriorates. With the frequency remaining essentially unchanged and the matching slightly better, when the frequency decreases, The resonant frequency increases and the matching improves, but The matching deteriorated, so we selected based on a comprehensive consideration. =8.5mm. For example... Figure 6 As shown, curves 1-3 are respectively =8mm, 8.5mm, 9mm S11 curves.

[0062] Dimensions of center groove 3: Length =15mm, width =3mm, optimized circular polarization performance. Enlargement will The frequency decreases, and vice versa. Increase will decrease Frequency, while increasing The frequency. For example... Figure 7 , Figure 8 As shown, curves 1-3 are respectively =14mm, 15mm, 16mm; =2mm, 3mm, 4mm.

[0063] Length of the second rectangular groove 8 Set to 13mm, adjust as needed. Optimize impedance matching for current path length in mode, taking into account both frequency point and impedance matching effectiveness, and select... =13mm. For example... Figure 9 As shown, curves 1-3 are respectively =12mm, 13mm, 14mm.

[0064] Length of the first rectangular groove 6 Set to 9.5mm, adjust as needed. The mode is used to optimize impedance matching and frequency. Changes Impedance matching and frequency are almost unaffected, but When it increases, When the resonant frequency decreases, the matching improves; when it decreases, As the resonant frequency increases, the matching deteriorates. Taking all factors into consideration, choose... =9.5mm. Width Set to 2mm. Changes Impedance matching and frequency are almost unaffected, but When the impedance is increased, the impedance matching effect improves slightly, and the frequency point decreases slightly. When the impedance is reduced, the impedance matching effect deteriorates, and the frequency point increases slightly. Taking all factors into account, the optimal choice is... =2mm. For example... Figure 10 As shown, curves 1-3 are respectively =9mm, 9.5mm, 10mm. For example... Figure 11 As shown, curves 1-3 are respectively =1.5mm, 2mm, 2.5mm.

[0065] Performance characteristics.

[0066] Dual-band coverage: Simultaneously supports 2.4GHz (directional circular polarization) and 5.7GHz (omnidirectional linear polarization) to meet the communication needs of WBAN in multiple scenarios.

[0067] High gain and polarization performance: High gain is achieved in both the 2.4GHz and 5.7GHz bands. The 2.4GHz band utilizes left-hand circular polarization to resist multipath interference, while the 5.7GHz band features high linear polarization purity and low transmission loss. Figure 5 As shown, the antenna exhibits a deep dip in the 2.4GHz band, with S11 below -10dB (actually -12.07dB), indicating good impedance matching within this band and meeting communication requirements. In the 5.7GHz band, S11 reaches an even lower value (-16.91dB), verifying the antenna's good operating characteristics in this band. The return loss in both resonant bands meets the requirements for engineering applications. Impedance matching requirement of "-10dB".

[0068] Integrated and flexible design: The single-patch multi-slot structure achieves dual-frequency, dual-mode, dual-polarization, reducing the volume by more than 60% compared to traditional solutions; the felt substrate and silver-plated conductive cloth ensure flexibility, wearing comfort, and bending stability.

[0069] Safety and low power consumption: The low dielectric constant substrate reduces electromagnetic coupling, with a SAR value of <1.6W / kg; the high gain characteristics allow for reduced transmit power and extended device battery life.

[0070] Example 2

[0071] A wearable device includes a dual-band, dual-mode, dual-polarized wearable antenna as described in Embodiment 1.

[0072] The dual-band, dual-mode, dual-polarized wearable antenna is integrated into the surface of the device body via flexible conductive adhesive or sewing. The antenna's radiating surface faces away from human tissue. A buffer layer made of medical-grade silicone, 1-3mm thick, is provided on the side of the device body that contacts the human body. This layer reduces discomfort from direct contact between the antenna and the body and further reduces the penetration of electromagnetic radiation into the body. This wearable device can be a smart bracelet, a health monitoring patch, or a smart chest strap. The overall thickness of the integrated antenna device does not exceed 8mm, and its weight does not exceed 50g, meeting the requirements for lightweight and low-profile wearability.

[0073] Example 3

[0074] A wireless communication system includes a dual-band, dual-mode, dual-polarized wearable antenna as described in Embodiment 1.

[0075] The wireless communication system also includes terminal devices, gateway nodes, and cloud nodes. Dual-band, dual-mode, dual-polarized wearable antennas serve as communication units for the terminal devices. Multiple terminal devices (e.g., health monitoring patches, smart tattoo stickers, smart chest straps, or smart wristbands) are worn on different parts of the user's body to collect and transmit physiological, motion, and environmental perception data. Each terminal device's dual-band, dual-mode, dual-polarized wearable antenna features adaptive mode switching: when terminal devices communicate over short distances on the body surface, the antenna operates in 5.7GHz omnidirectional linear polarization mode to ensure signal coverage of the body's curved surfaces and facilitate data exchange between devices; when a terminal device communicates with a gateway node over long distances, the antenna switches to 2.4GHz directional circular polarization mode. The gateway node is equipped with dual-band receiving antennas, capable of simultaneously receiving data transmitted from terminal devices in both the 5.7GHz and 2.4GHz bands. After data aggregation and protocol conversion, the data is uploaded to the cloud server via a wired network or a 5G / WiFi module. This wireless communication system is suitable for scenarios such as smart healthcare, sports and health, and industrial personnel monitoring. In smart healthcare scenarios, it can realize the real-time transmission and remote monitoring of multi-parameter physiological data (heart rate, blood oxygen, body temperature). In industrial personnel monitoring scenarios, it can collect personnel location and movement status data through terminal devices, and combine the directional communication characteristics of antennas to realize personnel positioning and early warning of dangerous areas.

[0076] It is worth noting that all contents not described in detail in this invention are existing technologies and are well known to those skilled in the art.

[0077] Therefore, the present invention adopts the above-mentioned dual-band dual-mode dual-polarization antenna based on mode modulation and its application. By optimizing the slot parameters and feed point position, it achieves efficient operation of dual frequency bands, solves the polarization mismatch problem, and achieves intelligent adaptation of dual modes.

[0078] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A dual-band, dual-mode, dual-polarization antenna based on mode modulation, comprising a flexible dielectric substrate, a circular metal radiating patch, a metal ground, and a feed point, wherein the upper surface of the flexible dielectric substrate is covered with the circular metal radiating patch, and the lower surface is covered with the metal ground, characterized in that, The circular metal radiating patch is etched with multiple slot structures, including a central slot, a first slot group, a second slot group, a T-shaped slot group, and a circular slot group. The central slot is an inclined rectangular slot that runs through the center of the circular metal radiating patch. The first slot group is symmetrically arranged along the y-axis of the circular metal radiating patch, and the second slot group is symmetrically arranged along the x-axis of the circular metal radiating patch. The T-shaped slot group contains four T-shaped slots, which are centrally symmetrically distributed with respect to the center of the circular metal radiating patch. The circular slot group contains four first circular slots, which are located on the same circumference with respect to the center of the circular metal radiating patch and are centrally symmetrically distributed. The slotted structure is configured to excite the circular metallic radiation patch. Pattern and The mode enables the antenna to operate in directional circular polarization mode in the 2.4 GHz band and omnidirectional linear polarization mode in the 5.7 GHz band; The first slot group includes two slot units. Each slot unit includes a first rectangular slot and a second circular slot connected to the end of the first rectangular slot. The length of each first rectangular slot is 9-10 mm and the width is 1.8-2.2 mm. The radius of each second circular slot is 0.8-1.2 mm. The four T-shaped slots are located at 45°, 135°, 225° and 315° of the circular metal radiating patch, respectively. Each T-shaped slot is composed of two orthogonal rectangles with lengths of 7.5-8mm and 3.5-4.5mm respectively and widths of 0.3-0.7mm. Each T-shaped groove has an additional rectangular groove etched along the angle bisector on both the left and right sides, with a length of 3.5-4.5 mm and a width of 0.3-0.7 mm.

2. The dual-frequency, dual-mode, dual-polarization antenna based on mode modulation according to claim 1, characterized in that, The central groove is set at -45° along the circular metal radiating patch, with a length of 14.5-15.5mm and a width of 2.5-3.5mm.

3. The dual-frequency, dual-mode, dual-polarization antenna based on mode modulation according to claim 1, characterized in that, The second slot group includes four second rectangular slots, each with a length of 12.6-13.4 mm and a width of 1-1.4 mm.

4. The dual-frequency, dual-mode, dual-polarization antenna based on mode modulation according to claim 1, characterized in that, The four first circular grooves of the circular groove group are located on a circle with a radius of 11-12 mm and are evenly distributed at 45°, 135°, 225° and 315°. The radius of each first circular groove is 1-1.5 mm.

5. The dual-frequency, dual-mode, dual-polarization antenna based on mode modulation according to claim 1, characterized in that, The power supply point is located on a circular metal radiating patch and is off-center from its center. The distance from the center of the circular metal radiating patch is 8.3-8.7 mm, and the radius of the circular metal radiating patch is 27.5-28 mm.

6. The dual-frequency, dual-mode, dual-polarization antenna based on mode modulation according to claim 1, characterized in that, The flexible dielectric substrate is a felt material substrate with a dielectric constant of 1.2, a loss tangent of 0.02, a thickness of 2 mm, and a radius of 33-35 mm.

7. A wearable device, characterized in that, Includes the dual-band dual-mode dual-polarized wearable antenna as described in any one of claims 1-6.

8. A wireless communication system, characterized in that, Includes the dual-band dual-mode dual-polarized wearable antenna as described in any one of claims 1-6.

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