Dual-band dual-mode dual-polarized wearable antenna

Abstract

The utility model discloses a kind of dual-frequency dual-mode dual-polarization wearable antennas, belong to antenna technical field.The antenna uses flexible substrate, which is provided with circular radiation patch and ground plane.Through etching multiple slot structure on circular radiation patch, including center inclined rectangular slot, rectangular slot and trapezoidal slot symmetrical along y axis, rectangular slot gap symmetrical along x axis, and T-shaped slot and U-shaped slot distributed on different azimuth angle, antenna can realize left-handed circular polarization directional radiation in 2.4GHz ISM frequency band, and realize linear polarization omnidirectional radiation in 5.5GHz Wi-Fi frequency band.The utility model uses above-mentioned one kind of dual-frequency dual-mode dual-polarization wearable antenna, antenna design is simple, excellent in performance, suitable for remote medical monitoring, high-speed data transmission and multiple application scenarios, with wide application prospect.

Description

Technical Field

[0001] This utility model relates to the field of antenna technology, and in particular to a dual-frequency, dual-mode, dual-polarization wearable antenna. Background Technology

[0002] With the widespread adoption of Wireless Body Area Network (WBAN) technology, wearable devices are placing higher demands on antenna performance. These devices need to operate in different scenarios, such as on-body communication and off-body communication. The former requires omnidirectional radiation to cover the curved surfaces of the human body, while the latter requires directional radiation to achieve long-distance transmission. The 2.4GHz ISM band and the 5.5GHz Wi-Fi band are the two core frequency bands for WBAN communication.

[0003] Currently, traditional wearable antenna designs face significant challenges in addressing the aforementioned multi-scenario, multi-frequency band requirements. First, the commonly used single-polarization antennas are prone to severe signal attenuation during human activity due to polarization mismatch. Second, existing technologies struggle to integrate omnidirectional and directional radiation modes within a single antenna structure, forcing devices to employ multi-antenna solutions, thus increasing system size, complexity, and power consumption. Furthermore, many antenna designs can only cover a single frequency band, or, while dual-band designs, suffer from narrow bandwidth, poor impedance matching, and performance coupling between frequency bands.

[0004] To address the polarization mismatch issue, the industry has introduced dual-polarization technology, but its implementation often presents new limitations. For example, using cross dipoles or double-layer microstrip patches results in excessively high antenna profiles, poor flexibility, and difficulty in integration; while metasurfaces and reconfigurable technologies can improve performance, they significantly increase design complexity and manufacturing costs, and are difficult to implement stably on flexible substrates.

[0005] Therefore, there is an urgent need in this field for an innovative antenna solution that can simultaneously achieve dual-band operation, dual-polarization characteristics, and dual-mode radiation under low-profile, flexible structural constraints. Utility Model Content

[0006] The purpose of this invention is to provide a dual-band, dual-mode, dual-polarization wearable antenna to meet the needs of wearable devices in different communication scenarios within a Wireless Body Area Network (WBAN). This antenna can achieve left-hand circular polarization directional radiation in the 2.4GHz ISM band and linear polarization omnidirectional radiation in the 5.5GHz Wi-Fi band. It also features low profile, flexibility, high gain, and low electromagnetic energy absorption, ensuring wearability and electromagnetic safety, making it suitable for applications such as remote medical monitoring and high-speed data transmission.

[0007] To achieve the above objectives, this utility model provides a dual-frequency, dual-mode, dual-polarization wearable antenna, comprising: Flexible substrate; A radiating layer disposed on a flexible substrate, the radiating layer comprising a circular radiating patch; Ground contact; The circular radiating patch is etched with multiple slot structures for exciting and controlling different operating modes, so that the antenna operates in circular polarization directional mode in the first frequency band and in linear polarization omnidirectional mode in the second frequency band. The multiple slot structures include: an inclined rectangular slot located at the center of the circular radiating patch, a pair of rectangular slots symmetrically arranged along the y-axis with trapezoidal slots at their ends, multiple rectangular gaps symmetrically arranged along the x-axis, and T-shaped slots and U-shaped slots distributed at different azimuth angles.

[0008] Preferably, the flexible substrate is made of felt material with a dielectric constant of 1.2 and a loss tangent of 0.02; the radiating layer and the ground plane are made of silver-plated conductive cloth.

[0009] Preferably, the diameter of the circular radiating patch is 26-28 mm.

[0010] Preferably, the length of the inclined rectangular groove is 13-14 mm and the width is 3.5-4.5 mm.

[0011] Preferably, the rectangular groove has a length of 7.5-8.5 mm and a width of 1.8-2.2 mm, and the bottom width of the trapezoidal groove at its end is 5.6-6.4 mm.

[0012] Preferably, four rectangular slits are symmetrically etched along the x-axis, with a length of 11.5-12.5 mm and a width of 1.4-1.8 mm.

[0013] Preferably, the T-shaped groove is located at 45° and 225° of the circular radiating patch, and the width of the rectangle it forms is 0.8-1.2 mm and the length is 5.5-6.5 mm; the U-shaped groove is located at -45° and 135° of the circular radiating patch.

[0014] Preferably, the upper side of the U-shaped groove has a length of 11-13mm, the lower side has a length of 13-15mm, and the width is 1mm.

[0015] Preferably, the antenna is fed through a 50Ω SMA connector, with the feeding point located on the circular radiating patch at a distance of 7.5-8.5mm from the center.

[0016] Preferably, the first frequency band is the 2.4GHz ISM band, and the operating mode is left-hand circularly polarized directional radiation; the second frequency band is the 5.5GHz Wi-Fi band, and the operating mode is linearly polarized omnidirectional radiation.

[0017] Therefore, the present invention employs the above-mentioned dual-frequency, dual-mode, dual-polarization wearable antenna, and its technical effects are as follows: (1) Through an integrated design that etches various slots (such as center-tilted slots, T-shaped slots, U-shaped slots, etc.) on a circular radiating patch, a single antenna structure can operate independently in two frequency bands without a complex feeding network: achieving left-hand circular polarization directional radiation in the 2.4 GHz band and linear polarization omnidirectional radiation in the 5.5 GHz band. This not only solves the problems of single mode and poor scene adaptability of traditional wearable antennas, but also significantly reduces the antenna size and system complexity.

[0018] (2) Through optimized structural parameters (such as the size and position of each slot and the position of the feed point), the antenna achieved extremely high gain in both target frequency bands (2.4 GHz and 5.5 GHz). This effect directly meets the urgent needs of wearable devices for strong signal coverage and high communication quality in applications such as remote medical monitoring and high-speed data transmission.

[0019] (3) By using a combination of a flexible felt substrate and silver-plated conductive cloth, the antenna possesses excellent flexibility and skin affinity, ensuring wearing comfort. At the same time, this flexible material with low dielectric constant and low loss, combined with a directional radiation mode, effectively reduces the electromagnetic energy absorption of human tissue, ensures electromagnetic safety when worn, and improves the performance stability of the antenna under bending conditions.

[0020] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the antenna of this utility model; Figure 2 This is the normalized radiation pattern of the antenna in the 5.5GHz xoz plane of this invention; Figure 3 This is the normalized radiation pattern of the antenna in the 2.4GHz xoz plane of this invention; Figure 4 This is the normalized radiation pattern of the antenna in the 5.5GHz xoy plane of this invention; Figure 5 This is a graph showing the return loss S11 of this invention as a function of frequency. Figure 6 Comparison of return loss S11 curves for different fy values; Figure 7 The effect of different L2 values ​​on S11; Figure 8 The effects of different W2 values ​​on S11; Figure 9The effect of different L4 values ​​on S11; Figure 10 The effect of different W values ​​on S11.

[0022] Figure Labels 1. Flexible substrate; 2. Circular radiating patch; 3. Inclined rectangular groove; 4. Rectangular groove; 5. Trapezoidal groove; 6. Rectangular gap; 7. T-shaped groove; 8. U-shaped groove; 9. Feed point. Detailed Implementation

[0023] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0024] Unless otherwise defined, the technical or scientific terms used in this utility model shall have the ordinary meaning understood by one of ordinary skill in the art to which this utility model pertains. The terms "first," "second," and similar terms used in this utility model do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0025] Example 1 This embodiment provides a dual-band, dual-mode, dual-polarization wearable antenna operating in the 2.4GHz ISM band and the 5.5GHz Wi-Fi band. Its specific structure and dimensions are as follows; directional terms not explicitly stated are... Figure 1 As shown below.

[0026] Substrate and Materials: The antenna adopts a double-layer structure. The flexible substrate 1 is made of a flexible felt material with a dielectric constant of 1.2 and a loss tangent of 0.02, with a thickness h = 2 mm and a radius R1 = 34 mm. Both the radiating layer and the ground plane are made of silver-plated conductive cloth with a thickness of 0.1 mm, which is tightly bonded to the flexible substrate 1 through a hot-pressing process to ensure good conductivity and bending durability.

[0027] Radiation patch structure: A circular radiation patch 2 with a radius R2 = 27 mm is etched on the radiation layer. Multiple slot structures for mode control and impedance matching are etched on this circular radiation patch 2.

[0028] Inclined rectangular groove 3: Located at the center of the circular radiating patch 2, etched at a -45° angle. Its length L2 = 13.5 mm and width W2 = 4 mm. Inclined rectangular groove 3 is used to break the TM. 11 The degeneracy of the mode excites a left-handed circularly polarized wave.

[0029] Y-axis rectangular and trapezoidal slots: Two rectangular slots 4 are symmetrically cut along the y-axis of the patch, with a length L1=8mm and a width W1=2mm. At the end of each rectangular slot 4, a trapezoidal slot 5 is etched. The shorter trapezoidal slot 5 has an upper width W1=2mm, a lower width W7=6mm, and a height h1=1.5mm.

[0030] X-axis rectangular slots: Four rectangular slots 6 are symmetrically etched along the x-axis of the patch, with a length L4 = 12 mm and a width W4 = 1.6 mm. This structure is mainly used for adjusting TM. 02 The mode's resonant frequency and impedance matching.

[0031] T-slots 7: A T-slot 7 is cut at both the 45° and 225° positions of the circular radiating patch 2. The length L = 6mm and the width W = 1mm of the two orthogonal rectangles constituting each T-slot 7. This structure is used to extend the current path and optimize high-frequency matching.

[0032] U-shaped slot 8: A U-shaped slot 8 is etched at both the -45° and 135° positions of the circular radiating patch 2. The upper side length L6 = 12mm, the lower side length L5 = 14mm, and the width W5 = 1mm of the U-shaped slot 8. This structure further optimizes the impedance matching of the antenna.

[0033] Feeding method: The antenna is fed through a 50Ω SMA connector. Feed point 9 is located on the circular radiating patch 2, offset from the center of the circle by fy = 8mm in the y-axis direction. This position is optimized to ensure good impedance matching for both the 2.4GHz and 5.5GHz frequency bands.

[0034] Operating mode and frequency band characteristics.

[0035] 2.4GHz band (directional circular polarization): such as Figure 3 As shown, the antenna is in the 2.45GHz (close to 2.4GHz) xoz plane (as shown). Figure 2The pattern (shown) presents a normalized radiation pattern with a unique double-lobed shape (similar to the number "8"), with the two main lobes distributed in the 0°-180° and 90°-270° regions, respectively. The gain in the 0° direction is close to 0dB, representing the maximum radiation direction, while the gain gradually decreases on both sides, dropping to approximately -20dB in the 90° direction. This radiation pattern demonstrates the directional radiation characteristics of this frequency band in the xoz plane, with radiated energy concentrated in a specific direction, making it suitable for close-range interaction scenarios on the body surface. Its operating mode uses a tilted rectangular slot to excite the mode and its degenerate mode, forming a left-handed circular polarization; the surface current is distributed along the patch diameter, and the tilted rectangular slot 3 modulates the rotation of the current path, generating orthogonal electric field components with a 90° phase difference, ultimately achieving directional radiation.

[0036] 5.5GHz band (omnidirectional linear polarization): such as Figure 2 As shown, the antenna's normalized radiation pattern in the xoz plane is butterfly-shaped, with two main lobes located at 30° and -90°, and 270° and -330° respectively. The main lobe gain is close to 0dB, with low values ​​(approximately -10dB) at 0° and 180°. This radiation pattern indicates that this frequency band has significant directional radiation characteristics in the xoz plane, with the maximum radiation concentrated near the 45° and 135° angles, making it suitable for directional communication scenarios. Figure 4 As shown, the antenna's normalized radiation pattern in the xoy plane is almost perfectly circular. The radiated energy distribution is uniform across 360° with only minor fluctuations, exhibiting no obvious main beam or specific directionality, demonstrating omnidirectional radiation characteristics. This frequency band achieves precise resonant frequency tuning to 5.5GHz by optimizing the slot structure to extend the current path; the surface current is radially distributed, and the electric field forms linear polarization along the z-axis, making it suitable for near-field interactive or auxiliary communication scenarios requiring omnidirectional coverage.

[0037] Parameter optimization and performance tuning.

[0038] Firstly, the position of feed point 9 needs optimization. fy affects the impedance matching between TM11 and TM02 modes. As fy increases, the resonant frequency of TM02 mode decreases, and the impedance matching effect deteriorates. 11 The mode resonant frequency remains almost unchanged, and the impedance matching effect is slightly improved; considering all factors, fy=8mm is chosen. Figure 6 As shown, curves 1-3 are S11 curves with diameters of 7mm, 8mm, and 9mm, respectively.

[0039] Secondly, the length L2 and width W2 of the inclined rectangular slot 3 loaded at the center of the antenna are important parameters that primarily affect the circular polarization performance of the antenna. As the length L2 increases, the TM... 02 The resonant point of the mode remains almost unchanged, while TM 11 The resonant point of the mode gradually shifts towards lower frequencies, and vice versa. Increasing the value of W2 lowers the frequency of TM02 while increasing the frequency of TM.11 Considering both frequency and gain, L2 = 13.5mm and W2 = 4mm were selected. Figure 7 , Figure 8 As shown, curves 1-3 are L2=13mm, 13.5mm, 14mm, and W2=3mm, 4mm, 5mm, respectively.

[0040] Thirdly, the length L4 of the four rectangular slots 6 etched along the X-axis; changing the length of L4 will change TM. 11 The equivalent current path length of the mode will affect the impedance matching effect of the antenna. Considering both frequency and impedance matching effect, L4=12mm is selected. Figure 9 As shown, curves 1-3 have L4 = 11mm, 12mm, and 13mm respectively.

[0041] Fourthly, the width W of the two T-slots 7; changing the value of W will change TM. 02 The equivalent current path length of the mode affects the antenna's frequency and impedance matching. When W increases, the frequency of the TM02 mode shifts slightly to the left, while the impedance matching worsens; when W decreases, the frequency remains almost unchanged, but the impedance matching becomes very poor. Considering both factors, W = 1 mm is chosen. Figure 10 As shown, curves 1-3 represent W=0.5mm, 1mm, and 1.5mm, respectively.

[0042] Performance characteristics.

[0043] Dual-band operation: It simultaneously covers the 2.4GHz ISM band and the 5.5GHz Wi-Fi band. The 2.4GHz directional circular polarization is adapted for long-distance external communication, and the 5.5GHz omnidirectional linear polarization is adapted for close-range interaction on the body surface, significantly improving scene adaptability.

[0044] Excellent dual-polarization performance: The left-hand circular polarization in the 2.4GHz band has strong anti-multipath interference capability; the linear polarization in the 5.5GHz band has high purity and low signal transmission loss. Dual-polarization switching does not require additional circuitry and has a simple structure.

[0045] High gain characteristics: This antenna achieves high gain in both the 2.4GHz and 5.5GHz frequency bands, meeting the requirements of high-speed data transmission and showing a significant improvement compared to other similar products. Figure 5As shown, the antenna's S11 curve exhibits a "valley" in the 2.4GHz band, with a return loss S11 value reaching -17.46dB, indicating good impedance matching within this band. The S11 "valley" is even more pronounced in the 5.5GHz band, reaching -25.3dB. Both bands meet the engineering impedance matching requirement of -10dB, verifying the consistency of the antenna's multi-band impedance matching design and performance at 2.4GHz and 5.7GHz.

[0046] Therefore, this utility model employs a dual-band, dual-mode, dual-polarization wearable antenna to meet the needs of wearable devices in different communication scenarios within a Wireless Body Area Network (WBAN). This antenna can achieve left-hand circular polarization directional radiation in the 2.4GHz ISM band and linear polarization omnidirectional radiation in the 5.5GHz Wi-Fi band. It also features low profile, flexibility, high gain, and low electromagnetic energy absorption, ensuring wearability and electromagnetic safety, making it suitable for applications such as remote medical monitoring and high-speed data transmission.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model 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 solution of this utility model, and these modifications or equivalent substitutions cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of this utility model.

Claims

1. A dual-frequency, dual-mode, dual-polarization wearable antenna, characterized in that, include: Flexible substrate; A radiating layer disposed on a flexible substrate, the radiating layer comprising a circular radiating patch; Ground contact; The circular radiating patch is etched with multiple slot structures for exciting and controlling different operating modes, so that the antenna operates in circular polarization directional mode in the first frequency band and in linear polarization omnidirectional mode in the second frequency band. The multiple slot structures include: an inclined rectangular slot located at the center of the circular radiating patch; a pair of rectangular slots symmetrically arranged along the y-axis with trapezoidal slots at their ends; multiple rectangular gaps symmetrically arranged along the x-axis; and T-shaped slots and U-shaped slots distributed at different azimuth angles.

2. The dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The flexible substrate is made of felt material with a dielectric constant of 1.2 and a loss tangent of 0.02; the radiating layer and the ground plane are made of silver-plated conductive cloth.

3. The dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The diameter of the circular radiating patch is 26-28mm.

4. The dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The length of the inclined rectangular groove is 13-14mm and the width is 3.5-4.5mm.

5. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The rectangular groove has a length of 7.5-8.5mm and a width of 1.8-2.2mm, while the bottom width of the trapezoidal groove at its end is 5.6-6.4mm.

6. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, Four rectangular slits are symmetrically etched along the x-axis, with a length of 11.5-12.5 mm and a width of 1.4-1.8 mm.

7. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The T-shaped grooves are located at the 45° and 225° positions of the circular radiating patch, forming a rectangle with a width of 0.8-1.2 mm and a length of 5.5-6.5 mm; the U-shaped grooves are located at the -45° and 135° positions of the circular radiating patch.

8. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 7, characterized in that, The upper part of the U-shaped groove is 11-13mm long, the lower part is 13-15mm long, and the width is 1mm.

9. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The antenna is fed through a 50Ω SMA connector, with the feed point located on the circular radiating patch at a distance of 7.5-8.5mm from the center.

10. A dual-frequency, dual-mode, dual-polarization wearable antenna according to claim 1, characterized in that, The first frequency band is the 2.4GHz ISM band, which operates in a left-hand circularly polarized directional radiation mode; the second frequency band is the 5.5GHz Wi-Fi band, which operates in a linearly polarized omnidirectional radiation mode.

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