A wearable textile antenna based on substrate integrated waveguide

Abstract

The present invention discloses a wearable fabric antenna based on substrate integrated waveguide. The antenna comprises an upper metal patch, a dielectric substrate layer, a lower metal ground and a feeding probe arranged in sequence from top to bottom; a metal through hole array penetrating the dielectric substrate is provided on the dielectric substrate layer; the metal through hole array connects the upper metal patch and the lower metal ground. The metal through hole array, the upper metal patch and the lower metal ground together form a semicircular substrate integrated waveguide cavity; the feeding probe is connected to the upper metal patch and the lower metal ground respectively. The upper metal patch is a circular patch with a cutout and a curved rectangular gap etched therein, the cutout forms an open edge for adjusting the resonant frequency of the substrate integrated waveguide cavity, and the curved rectangular gap is used to radiate electromagnetic waves. Compared with general fabric wearable antennas, the antenna has the advantages of novel structure, wide bandwidth, good stability, low cost, and easy integration with the human body.

Description

Technical Field

[0001] The present invention relates to the field of antenna technology, and in particular to a wearable fabric antenna based on substrate integrated waveguide. Background Art

[0002] In recent years, human-centered antennas have become a research hotspot at home and abroad. Human-centered antennas include applications implanted in the human body and applications worn on the human body surface. Among them, the main applications of wearable antennas are sports bracelets, smart watches, and VR devices. In addition, they can also be used to monitor the physiological characteristics of the human body, realize telemedicine, collect human physiological information in real time, and build a human health database.

[0003] Antennas are essential components for receiving and sending information in wireless networks. Wearable antennas are also an essential part of communications used in body area networks. The complexity of the impact of the human electromagnetic environment poses a great challenge to the design of wearable antennas. In addition, when acting on different parts of the human body, it will also cause bending, shrinking and other conditions, thereby changing the resonant frequency of the antenna. Therefore, the design of wearable antennas requires wide bandwidth and good stability. Wearable antennas made of fabrics have the advantages of being easy to conform to human clothes, comfortable, and low-profile, and are commonly used materials for wearable antennas. Among the existing wearable antennas, the monopole antenna structure is generally adopted (Lin Xuechen, Zhang Binzhen, Duan Junping, et al. Flexible wearable microstrip antenna based on PDMS [J]. Micro-Nano Electronics Technology, 2018 (7).) or microstrip antenna structure (Yang Hong, Du Xiaoyang, Ye Qingsong. Design of wearable dual-band antenna based on textile materials [J]. Electronic Quality, 2018 (3): 34-37. Gao Guoping. Research on ultra-wideband and wearable antennas in wireless body area network (WBAN) [D].). Although these two structures are simple in structure and easy to manufacture, they can be easily affected by the human body and affect the antenna performance. Substrate integrated waveguide is a technology that connects parallel metal sheets up and down through metal vias to form a resonant cavity. It has a good function of shielding the human body, and has the advantages of high quality factor, high power capacity, low insertion loss and radiation loss, and easy integration with planar circuits. The substrate integrated waveguide wearable antenna with fabric as the material can well shield the influence of the human body on the antenna, and has the advantages of high stability, low cost, and easy integration. Summary of the invention

[0004] In order to solve the problems and shortcomings in the prior art, the present invention proposes a wearable fabric antenna based on substrate integrated waveguide, which has the advantages of strong robustness, wide bandwidth, low cost, high radiation efficiency, and easy integration.

[0005] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0006] A wearable fabric antenna based on substrate integrated waveguide comprises an upper metal patch, a dielectric substrate layer, a lower metal ground and a feeding probe arranged in sequence from top to bottom; a metal through hole array penetrating the dielectric substrate is arranged on the dielectric substrate layer; the metal through hole array connects the upper metal patch and the lower metal ground;

[0007] The metal through hole array, the upper metal patch and the lower metal ground together form a semicircular substrate integrated waveguide cavity; the feeding probe is connected to the upper metal patch and the lower metal ground respectively.

[0008] The upper metal patch is a circular patch with a cutout and a curved rectangular gap etched therein, wherein the cutout forms an open edge, and the resonant frequency of the substrate integrated waveguide cavity is adjusted by adjusting the size of the cutout; the curved rectangular gap is used to radiate electromagnetic waves.

[0009] Furthermore, the width of the incision is 10.5mm~11.5mm; the overall size of the curved rectangular gap is 7.5mm~8.5mm×18.5mm~19.5mm, located in the center of the patch, and 6.5mm~7.5mm away from the open edge; the width of each rectangular gap is 0.9mm~1.1mm, and each small gap is 0.9mm~1.1mm apart. The electric field of the substrate integrated waveguide cavity is mainly distributed around the curved rectangular gap, and the curved rectangular gap cuts the surface current to form a displacement current, thereby effectively radiating the electromagnetic wave.

[0010] Furthermore, the inner core of the feeding probe is connected to the upper metal patch, and the inner core is placed on the left and right central axes of the entire antenna structure. Impedance matching is achieved by adjusting the distance between the feeding probe and the curved rectangular gap and open edge on the upper metal patch; the outer core of the feeding probe is connected to the lower metal ground.

[0011] Furthermore, the dielectric substrate layer is made of a felt material, the relative dielectric constant of the felt material is 1.2, and the dielectric loss is 0.02. The dielectric substrate layer is a cylinder with a height of 1.9 mm to 2.1 mm and a radius of 17 mm to 19 mm.

[0012] Furthermore, the lower metal ground completely covers the lower surface of the dielectric substrate layer, with a radius of 17 mm to 19 mm; the upper metal patch and the lower metal ground are both made of conductive metal fabric, the thickness of the metal fabric is 0.12 mm to 0.14 mm, and its surface resistivity is less than 0.009 Ω / sq.

[0013] Furthermore, the metal through hole array is arranged on the semicircular periphery of the dielectric substrate layer; the metal through holes of the metal through hole array are made of brass eyelets with a radius of 0.73mm to 0.77mm, and the centers of two adjacent metal through holes are connected to the center of the dielectric substrate layer to form an angle of 9° to 11°; a total of 18 to 20 metal through holes are arranged on the dielectric substrate layer, forming a cylindrical substrate integrated waveguide cavity with the upper metal patch and the lower metal ground.

[0014] Furthermore, the feeding probe adopts a coaxial line with a characteristic impedance of 49Ω to 51Ω, an inner core radius of 0.4mm to 0.6mm, and an outer core radius of 1.1mm to 1.3mm.

[0015] Furthermore, the working ISM frequency band of the antenna is 5.8 GHz, the impedance bandwidth of 10 dB in free space is 5.61-6.13 GHz, the absolute bandwidth is 0.52 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 5.8 dBi; when acting in the human body, the 10 dB impedance bandwidth is 5.61-6.12 GHz, the absolute bandwidth is 0.51 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 4.1 dBi; the antenna mainly works in TM20 mode.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The substrate integrated waveguide slot antenna has the characteristics of high Q value and narrow bandwidth. The present invention adopts a substrate integrated waveguide structure with a semi-open edge and a circular half-mode resonance mode to effectively reduce the Q value, thereby widening the bandwidth, which is suitable for the design requirements of wearable antennas.

[0018] (2) The present invention adopts all-fabric to make a wearable antenna based on substrate integrated waveguide, which has the advantages of easy conformity with human clothes and low cost. Since the ground of the cavity is complete and the resonance cavity is highly independent, the performance of the antenna is little affected by the human body, which is suitable for wearable antenna design.

[0019] (3) The cutout of the upper metal patch of the present invention can not only adjust the resonant frequency of the resonant cavity, but also effectively reduce the radiation of the open edge due to the offset with the ground, thereby improving the radiation efficiency.

[0020] (4) In the present invention, a curved slot structure is etched on the surface of the substrate integrated waveguide cavity, which can effectively extend the displacement current path, thereby making the antenna structure more compact. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1a An overall top view of a wearable fabric antenna based on a substrate integrated waveguide provided in an embodiment;

[0022] Figure 1b An overall front view of a wearable fabric antenna based on a substrate integrated waveguide provided in an embodiment;

[0023] Figure 1c The overall left view of a wearable fabric antenna based on substrate integrated waveguide provided in the embodiment;

[0024] Figure 1d A structural diagram of an upper metal patch of a wearable fabric antenna based on a substrate integrated waveguide provided in an embodiment;

[0025] Figure 2 A model diagram of a wearable fabric antenna based on substrate integrated waveguide placed on three layers of human tissue provided in an embodiment;

[0026] Figure 3 A diagram showing the simulation results of the input end reflection coefficient of the substrate integrated waveguide-based wearable textile antenna provided in the embodiment in free space and a three-layer human tissue model;

[0027] Figure 4 A diagram showing the simulation results of the input reflection coefficient of a wearable textile antenna based on a substrate integrated waveguide in a bent state provided in an embodiment.

[0028] Figure 5a A simulation diagram of the xoz plane radiation pattern of a wearable textile antenna based on a substrate integrated waveguide at 5.8 GHz provided in an embodiment, wherein the solid line is the main polarization and the dotted line is the cross polarization.

[0029] Figure 5b A simulation diagram of the YOZ plane radiation direction of a wearable textile antenna based on a substrate integrated waveguide at 5.8 GHz provided in an embodiment, wherein the solid line is the main polarization and the dotted line is the cross polarization. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is described in more detail below in conjunction with the accompanying drawings and embodiments, but the implementation of the present invention is not limited thereto.

[0031] Example:

[0032] A wearable fabric antenna based on substrate integrated waveguide, such as Figure 1a and Figure 1c As shown, it includes an upper metal patch 1, a dielectric substrate layer 7, a lower metal ground 2 and a feeding probe arranged in sequence from top to bottom; a metal through hole array 5 penetrating the dielectric substrate is provided on the dielectric substrate layer 7; the metal through hole array 5 connects the upper metal patch 1 and the lower metal ground 2.

[0033] like Figure 1b and Figure 1cAs shown, the metal through hole array 5, the upper metal patch 1, and the lower metal ground 2 together form a semicircular substrate integrated waveguide cavity; the feeding probe is connected to the upper metal patch 1 and the lower metal ground 2 respectively.

[0034] like Figure 1d As shown, the upper metal patch 1 is a circular patch with a cut and a curved rectangular gap 4 etched therein, wherein the cut forms an open edge 8, and the resonant frequency of the substrate integrated waveguide cavity is adjusted by adjusting the size of the cut; the curved rectangular gap 4 is used to radiate electromagnetic waves.

[0035] The width of the incision is 10.5mm~11.5mm; the overall size of the curved rectangular gap 4 is 7.5mm~8.5mm×18.5mm~19.5mm, located in the center of the patch, and 6.5mm~7.5mm away from the open edge 8; the width of each rectangular gap is 0.9mm~1.1mm, and each small gap is 0.9mm~1.1mm apart. The electric field of the substrate integrated waveguide cavity is mainly distributed around the curved rectangular gap 4, and the curved rectangular gap 4 cuts the surface current to form a displacement current, which effectively radiates the electromagnetic wave.

[0036] The inner core 3 of the feeding probe is connected to the upper metal patch 1, and the inner core is placed on the left and right central axes of the entire antenna structure. Impedance matching is achieved by adjusting the distance between the feeding probe and the curved rectangular gap 4 and the open edge 8 on the upper metal patch 1; the outer core 6 of the feeding probe is connected to the lower metal ground 2.

[0037] The dielectric substrate layer 7 is made of felt material, the relative dielectric constant of the felt material is 1.2, and the dielectric loss is 0.02. In this embodiment, the dielectric substrate layer 7 is a cylinder with a height of 2 mm and a radius of 18 mm.

[0038] The lower metal ground 2 completely covers the lower surface of the dielectric substrate layer 7, and has a radius of 17 mm to 19 mm; the upper metal patch 1 and the lower metal ground 2 are both made of conductive metal fabric. In this embodiment, the thickness of the metal fabric is 0.13 mm, and its surface resistivity is less than 0.009 Ω / sq.

[0039] The metal through hole array 5 is arranged on the semicircular periphery of the dielectric substrate layer 7; the metal through holes of the metal through hole array 5 are made of brass eyelets with a radius of 0.73mm to 0.77mm, and the center of two adjacent metal through holes is connected to the center of the dielectric substrate layer 7 to form an angle of 9° to 11°; a total of 18 to 20 metal through holes are arranged on the dielectric substrate layer 7, forming a cylindrical substrate integrated waveguide cavity with the upper metal patch 1 and the lower metal ground 2.

[0040] In this embodiment, the feeding probe adopts a coaxial line with a characteristic impedance of 50Ω, an inner core radius of 0.5mm, and an outer core radius of 1.2mm.

[0041] The working ISM frequency band of the antenna is 5.8 GHz, the impedance bandwidth of 10 dB in free space is 5.61-6.13 GHz, the absolute bandwidth is 0.52 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 5.8 dBi; when acting in the human body, the 10 dB impedance bandwidth is 5.61-6.12 GHz, the absolute bandwidth is 0.51 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 4.1 dBi; the antenna mainly works in TM20 mode.

[0042] like Figure 2 As shown, the present invention mainly acts on the outside of the human body, and the present invention is jointly modeled with a three-layer human tissue structure, and the relative dielectric constant and conductivity of the human tissue are the corresponding electrical characteristics at 5.8GHz. The model is the upper layer of human skin, with a thickness of 1mm, a relative dielectric constant of 35.1, and a conductivity of 3.7s / m; the middle layer is human fat, with a thickness of 2mm, a relative dielectric constant of 4.9, and a conductivity of 0.29s / m; the middle layer is human muscle, with a thickness of 10mm, a relative dielectric constant of 48.5, and a conductivity of 4.9s / m.

[0043] like Figure 3 As shown, the present invention covers the 5.8GHz frequency band of ISM (5.725-5.875GHz), the 10dB impedance bandwidth in free space is 5.61-6.13GHz, the relative bandwidth is 9.0%, and the 10dB impedance bandwidth in the three-layer human tissue model is 5.61-6.12GHz, the relative bandwidth is 9.0%; the performance on the human body and the performance in free space are basically unchanged, indicating that the substrate integrated waveguide cavity structure has good shielding properties and is suitable for wearable antenna design.

[0044] like Figure 4 As shown, the echo impedance coefficient, resonant frequency and impedance bandwidth of the present invention in a bending state are basically not affected by the bending radius, which shows that the present invention has good stability.

[0045] like Figure 5a and Figure 5b As shown, the radiation pattern of the present invention at 5.8 GHz has a cross-polarization ratio of less than 30 dB in the main radiation direction and a maximum gain of 5.8 dBi in the main direction.

[0046] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any equivalent changes, modifications or evolutions made by those skilled in the art to the above embodiment using the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A wearable fabric antenna based on substrate integrated waveguide, characterized in that: It comprises an upper metal patch (1), a dielectric substrate layer (7), a lower metal ground (2) and a feeding probe which are arranged in sequence from top to bottom; A metal through hole array (5) penetrating the dielectric substrate is provided on the dielectric substrate layer (7); the metal through hole array (5) connects the upper metal patch (1) and the lower metal ground (2); The metal through hole array (5), the upper metal patch (1), and the lower metal ground (2) together form a semicircular substrate integrated waveguide cavity; the feeding probe is connected to the upper metal patch (1) and the lower metal ground (2) respectively; the upper metal patch (1) is a circular patch with a cutout and a curved rectangular gap (4) etched therein, the cutout forms an open edge (8), and the resonant frequency of the substrate integrated waveguide cavity is adjusted by adjusting the size of the cutout; the curved rectangular gap (4) is used to radiate electromagnetic waves; the dielectric substrate layer (7) is made of felt material; the dielectric substrate layer (7) is a cylinder with a height of 1.9 mm to 2.1 mm and a radius of 17 mm to 19 mm; the lower metal ground (2) completely covers the lower surface of the dielectric substrate layer (7) and has a radius of 17 mm to 19 mm; the metal through hole array (5) is arranged on the semicircular periphery of the dielectric substrate layer (7).

2. A wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The width of the cut is 10.5 mm to 11.5 mm; the overall size of the curved rectangular slit (4) is 7.5 mm to 8.5 mm × 18.5 mm to 19.5 mm, and it is located in the center of the patch and 6.5 mm to 7.5 mm away from the open edge (8); the width of each rectangular slit is 0.9 mm to 1.1 mm, and each small slit is separated by 0.9 mm to 1.1 mm. The electric field of the substrate integrated waveguide cavity is mainly distributed around the curved rectangular slit (4), and the curved rectangular slit (4) cuts the surface current to form a displacement current, thereby effectively radiating electromagnetic waves.

3. A wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The inner core (3) of the feeding probe is connected to the upper metal patch (1), and the inner core is placed on the left and right central axes of the entire antenna structure. Impedance matching is achieved by adjusting the distance between the feeding probe and the curved rectangular gap (4) and the open edge (8) on the upper metal patch (1); the outer core (6) of the feeding probe is connected to the lower metal ground (2).

4. The wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The relative dielectric constant of the felt material is 1.2, and the dielectric loss is 0.

02.

5. The wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The upper metal patch (1) and the lower metal ground (2) are both made of conductive metal fabric, the thickness of the metal fabric is 0.12 mm to 0.14 mm, and the surface resistivity is less than 0.009 Ω / sq.

6. The wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The metal through holes of the metal through hole array (5) are made of brass eyelets with a radius of 0.73 mm to 0.77 mm. The centers of two adjacent metal through holes are connected to the center of the dielectric substrate layer (7) to form an angle of 9° to 11°. A total of 18 to 20 metal through holes are arranged on the dielectric substrate layer (7) to form a cylindrical substrate integrated waveguide cavity with the upper metal patch (1) and the lower metal ground (2).

7. The wearable textile antenna based on substrate integrated waveguide according to claim 3, characterized in that: The feeding probe adopts a coaxial line with a characteristic impedance of 49Ω to 51Ω, an inner core radius of 0.4mm to 0.6mm, and an outer core radius of 1.1mm to 1.3mm.

8. The wearable textile antenna based on substrate integrated waveguide according to claim 1, characterized in that: The working ISM frequency band of the antenna is 5.8 GHz, the impedance bandwidth of 10 dB in free space is 5.61-6.13 GHz, the absolute bandwidth is 0.52 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 5.8 dBi; when acting in the human body, the 10 dB impedance bandwidth is 5.61-6.12 GHz, the absolute bandwidth is 0.51 GHz, the relative bandwidth is 9.0%, and the gain in the main radiation direction is 4.1 dBi; the antenna works in TM20 mode.

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