WO2020164498A1

WO2020164498A1 - Reflection member applied to antenna close to human body

Info

Publication number: WO2020164498A1
Application number: PCT/CN2020/074800
Authority: WO
Inventors: 马波力; 林永义; 黄漪; 王炤; 裴睿; 王璟琛
Original assignee: 西交利物浦大学
Priority date: 2019-02-12
Filing date: 2020-02-12
Publication date: 2020-08-20
Also published as: CN109755754A

Abstract

Disclosed is a reflection member applied to an antenna close to a human body, comprising an upper surface part of a conductive fiber material, a medium of a woven fiber material and a bottom plate of conductive fiber material, wherein the upper surface part is formed by a plurality of conductive fiber patches, which are arranged in multiple rows and in multiple columns, and each conductive fiber patch is in the shape of the Chinese character "回".

Description

Reflector applied to antenna close to human body

This disclosure claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201910111363.5 on February 12, 2019, and the entire content of the above application is incorporated into this disclosure by reference.

Technical field

This application belongs to the field of wireless communication technology, for example, it relates to a reflector applied to an antenna close to the human body.

Background technique

Wearable devices are electronic devices that can be directly worn by users. Such equipment is often integrated into clothing, clothing decoration accessories, or other wearing accessories. The more successful commercial wearable devices include smart watches, smart bracelets and smart glasses.

Common wearable devices basically have data collection and data transmission capabilities at the same time. The ability of wearable devices is inseparable from the huge advantages brought by data interaction, cloud processing and control. Therefore, wireless communication modules play a very important role in wearable devices. In addition to the conventional on-board antennas, some antennas specially designed for wearable devices can improve the communication efficiency of these devices.

The design of wearable device antennas generally prioritize the use of metal parts in some wearables, such as glasses temples and frames, metal buttons, zippers or belt buckles. Since this type of wearable antenna is used close to the human body, two factors must be considered:

First, the dielectric properties of the human body will affect the antenna performance. When the human body is close to the antenna, the dielectric properties of the human body will affect the antenna's resonant frequency, radiation direction and other important properties. For users of different heights, weights, and ages, the impacts are likely to be different due to the different volume and thickness of the user's body tissues. At the same time, for the same user, the antennas are located in different positions of the body will also affect the performance of the antenna.

Second: The electromagnetic radiation generated by the antenna will be absorbed by the human body. In order to ensure safety, several international standards organizations have set limits on the maximum radiation absorption. Radiation absorption is mainly measured by Specific Absorption Rate (SAR). The Institute of Electrical and Electronics Engineers (IEEE, Institute of Electrical and Electronics Engineers) stipulates in the standard document IEEE/IEC 62704-1 a method for calculating the average specific absorption rate through the finite difference time domain method. During the design and simulation of the wearable antenna, the specific absorption rate should also be calculated and taken into account.

In order to reduce the human body's influence on the wearable antenna and at the same time reduce the human body's absorption of radiation, in related technologies, a reflector is added to the side of the wearable antenna close to the human body. However, in the related art, an ordinary metal reflector (the reflector has a reflective surface) is provided. In order to have a reflection effect without affecting the operating frequency of the antenna, it is generally necessary to make the reflector a quarter of the distance from the antenna or other radiation unit. One to one-half wavelength. Such a distance requirement is inappropriate in the application of a wearable antenna.

Summary of the invention

The present application provides a reflector applied to an antenna close to the human body, which can reduce the radiation specific absorption rate of the wearable antenna to the human body, and at the same time increase the antenna gain toward the outside of the human body.

This application is realized through the following technical solutions:

A reflector applied to an antenna close to the human body, comprising an upper surface portion of conductive fiber material, a medium of fabric fiber material, and a bottom plate of conductive fiber material. The upper surface portion is composed of a plurality of conductive fibers arranged in multiple rows and rows. It is composed of fiber patches, and each conductive fiber patch is in a back shape.

Description of the drawings

Figure 1 is a schematic structural diagram of an embodiment of the application;

Figure 2 is a schematic diagram of the use of an embodiment of the application;

Fig. 3 is an antenna pattern of a wearable antenna when an embodiment of the present application is worn and not worn.

detailed description

The application will be described in detail below in conjunction with the drawings and specific implementations:

As shown in a specific implementation of the present application, as shown in FIG. 1, a reflector applied to an antenna close to the human body. The reflector applied to the antenna close to the human body may be a fabric metamaterial reflector applied to the antenna close to the human body. The upper surface of the conductive fiber material, the medium 1 of ordinary fabric fiber material, and the bottom plate of the conductive fiber material are included. The upper surface of the conductive fiber is composed of a plurality of rows and multiple columns of conductive fiber patches 2. The common fabric fiber material medium 1 and the conductive fiber material bottom plate completely overlap. The length of the ordinary fabric fiber material medium 1 and the conductive fiber material bottom plate is 120 mm and the width is 90 mm, and the relative dielectric constant of the ordinary fabric fiber material medium 1 is 1.6. The upper surface of the conductive fiber is composed of three-row and four-column-shaped conductive fiber patch 2. The side length of the outer square of each back-shaped conductive fiber patch 2 is 26mm, the side length of the hollowed-out part of the outer square is 12mm, and the side length of the inner small square patch is 8mm.

In some embodiments, the reflector applied to the antenna close to the human body includes an upper surface portion of conductive fiber material, a medium of fabric fiber material, and a bottom plate of conductive fiber material. The upper surface portion is arranged in multiple rows and rows. The cloth is composed of a plurality of conductive fiber patches, and each conductive fiber patch is in a back shape.

In some embodiments, the medium and the bottom plate coincide.

In some embodiments, the length of the medium and the bottom plate are both 120 mm, and the width of the medium and the bottom plate are both 90 mm.

In some embodiments, the upper surface portion is composed of the conductive fiber patch in three rows and four columns.

In some embodiments, each of the conductive fiber patches includes an outer square portion and an inner square portion, the outer square portion has a side length of 26 mm, and the outer square portion has a square hollow portion, and The side length of the empty part is 12 mm, and the side length of the inner square part is 8 mm.

In some embodiments, the relative dielectric constant of the medium is 1.6.

In some embodiments, the upper surface portion, the medium, and the bottom plate are all arranged in a plate shape.

In some embodiments, the bottom plate, the medium, and the upper surface portion are configured to be sequentially arranged in a direction away from the human body, and the upper surface portion and the bottom plate are respectively attached to the two sides of the medium. side.

In some embodiments, the medium may be a plate with a rectangular cross section, and the length and width of the medium refer to the length and width of the rectangular cross section of the medium, respectively.

In some embodiments, the bottom plate may be a plate with a rectangular cross section, and the length and width of the bottom plate refer to the length and width of the rectangular cross section of the bottom plate, respectively.

In some embodiments, in each of the conductive fiber patches,

The outer square part includes: a main body part having a plate shape with a square cross-section;

The side length of the outer square part refers to the side length of the square section of the main body part;

The center of the main body part is provided with the hollow part arranged in a square shape, the hollow part is configured to penetrate the main body part in a direction away from the human body, and the side length of the hollow part refers to: The side length of the square section of the hollowed out part;

The inner square part is located in the hollowed-out part of the outer square part.

The application scenario of the present application is shown in FIG. 2, the fabric metamaterial reflector (ie, the reflector applied close to the antenna of the human body) can be stitched onto the clothing and placed under the wearable antenna 4.

The design of the surface of the fabric metamaterial reflector in this application uses the concept of metamaterial. The conductive fiber of the back-shaped patch itself produces inductance, while the hollowed-out part of the outer square produces capacitance. The combination of inductance and capacitance changes the dielectric constant and permeability of the material, so it can produce different refraction and reflection coefficients for electromagnetic waves. Through the selection of patch size, the phase angle of reflection can be controlled at about 0 degrees, so that the fabric reflector can be placed directly under the antenna.

In the simulation, the human body voxel model is used for simulation, and the human body is standing by using CST (Computer Simulation Technology) software. The radiation of a wearable belt antenna with and without the reflector of this example Comparison of effects, the specific results are shown in Figure 3. Among them, (a) and (b) are without the reflector, the maximum gain of the belt antenna is 4.373dBi at 2.45GHz. According to the test method in IEEE/IEC 62704-1, the specific absorption rate value obtained when the input power is 0.5W is 2.682W/kg. (c) and (d) are that when the reflector of this example is added behind the antenna, the maximum gain of the belt antenna increases to 6.904dBi at 2.45GHz. According to the test method in IEEE/IEC 62704-1, the specific absorption rate value obtained when the input power is 0.5W is reduced to 0.142W/kg. This embodiment significantly improves the radiation effect of the antenna and reduces the human body's absorption of radiation.

It is understandable that, in the antenna pattern shown in Figure 3, Theta and Phi are the bases of the spherical coordinate system; Theta/Degree vs.dB is the dB value that varies with the angle of Theta; Phi/Degree vs.dB is the Phi The dB value of the angle change.

In this application, due to the application of fabrics and conductive fiber materials, the reflector can be integrated in the clothing where a wearable antenna is needed. After using the fabric metamaterial reflector of the present application, the radiation specific absorption rate of the wearable antenna to the human body will be greatly reduced. At the same time, the antenna gain toward the outside of the human body will be significantly improved.

Claims

A reflector applied to an antenna close to the human body, comprising an upper surface portion of conductive fiber material, a medium of fabric fiber material, and a bottom plate of conductive fiber material. The upper surface portion is composed of a plurality of conductive fibers arranged in multiple rows and rows. It is composed of fiber patches, and each conductive fiber patch is in a back shape.
The reflector applied to the antenna close to the human body according to claim 1, wherein the medium and the bottom plate overlap.
The reflector applied to the antenna close to the human body according to claim 2, wherein the length of the medium and the bottom plate are both 120 mm, and the width of the medium and the bottom plate are both 90 mm.
The reflector applied to the antenna close to the human body according to claim 3, wherein the upper surface part is composed of the conductive fiber patches in three rows and four columns.
The reflector applied to an antenna close to the human body according to claim 4, wherein each of the conductive fiber patches includes an outer square portion and an inner square portion, the outer square portion has a side length of 26mm, and the outer square The part has a square hollow part, the side length of the hollow part is 12 mm, and the side length of the inner square part is 8 mm.
The reflector applied to an antenna close to the human body according to claim 1, wherein the relative dielectric constant of the medium is 1.6.