Ad-hoc network radio station fabric antenna based on defected ground structure

Abstract

The invention belongs to the technical field of ad-hoc network wireless communication, and particularly relates to an ad-hoc network radio station fabric antenna based on a defected ground structure, which comprises a top conductive layer, a middle dielectric layer and a bottom conductive layer, the top conductive layer is of a square annular structure and is provided with a chamfer; the bottom conducting layer is of a square structure, and a square defected ground consistent with the top conducting layer in width is arranged in the middle of the bottom conducting layer; the middle dielectric layer is made of a flexible fabric material, and the top surface and the bottom surface of the middle dielectric layer are correspondingly connected with the top conductive layer and the bottom conductive layer in an attached mode. The invention aims to solve the problems that in the process that an ad hoc network radio station antenna develops towards a wearable and flexible trend, low frequency and large wavelength are difficult to apply under the conditions of low profile and small space; the low profile causes great reduction of antenna efficiency and performance; and the current flexible fabric antenna cannot meet connection and deployment requirements in practical application.

Description

Technical Field

[0001] The invention belongs to the technical field of ad hoc network wireless communication, and in particular relates to an ad hoc network radio station fabric antenna based on a defective ground structure. Background Art

[0002] A self-organizing radio is a wireless communication device that can automatically establish, maintain and repair a network without relying on traditional infrastructure. It achieves efficient and real-time information transmission and sharing through close collaboration between nodes, providing a fast-deployed, flexible and reliable communication solution, playing an important role in military command, traffic management, field rescue and emergency response. Currently, the most widely used is the handheld self-organizing radio, which is usually deployed as a wearable device around the waist or back. Among them, the self-organizing radio antenna, as the core functional device for realizing wireless transmission and reception of electromagnetic waves, is mainly a rod-shaped or whip-shaped metal antenna with a typical gain of 3dBi; however, with the improvement of ergonomics and performance requirements of wearable applications, the problems caused by traditional metal self-organizing radio antennas, such as cable hooking, affecting limb movement and complex structure, need to be solved urgently.

[0003] Fabric antenna is a flat flexible wearable antenna based on fabric material, with the characteristics of low profile and high flexibility. Its appearance is more concealed, easy to be compatible with the human body, and has higher directionality. It can better solve the problems of the above-mentioned metal antennas of self-organizing radio stations. At present, domestic and foreign research teams have carried out a lot of research and practice on the flexible materials, preparation process, antenna structure, electromechanical coupling, and other wearable analysis and optimization technologies of flexible fabric antennas; however, the existing fabric antenna technology applied to self-organizing radio stations still has the following unresolved problems:

[0004] (1) The wavelength of low-frequency antennas is larger, and flexible fabric antennas are more difficult to apply;

[0005] As the application of 5G communication technology becomes more and more widespread, flexible fabric antennas are more oriented towards 2.4G, 5G and WIFI applications. The operating frequencies of 2.4G, 5G and WIFI antennas are all relatively high, with relatively short wavelengths, and are easily implemented on low-profile fabric substrates. However, the operating frequency of ad hoc network radio antennas is relatively low (usually lower than 1.5GHz, and the frequency range of the ad hoc network radio targeted by the present invention is 1.35GHz to 1.39GHz), and the wavelength is relatively large, so it is difficult to apply and realize miniaturized design on low-profile fabric substrates, and there is currently no relevant technology.

[0006] (2) At extremely low profiles, the efficiency and performance of flexible fabric antennas are greatly reduced;

[0007] The flexible fabric antenna of the ad hoc radio station requires an extremely low profile to ensure the antenna flexibility. The typical relative thickness of a single layer of fabric is about 0.001λ (the free space wavelength corresponding to the frequency). The typical profile thickness of a traditional rigid microstrip antenna is about 0.02λ, a difference of 20 times. Under extremely low profile, the efficiency and performance of the antenna are greatly reduced. How to achieve higher performance of the antenna in an extremely low profile flexible design has become a key technical issue for the fabric antenna of the ad hoc radio station.

[0008] (3) Lack of flexible fabric antenna designs for practical applications;

[0009] The design of existing flexible fabric antennas has not deviated from the concept of traditional rigid antennas. After the antenna processing and testing are completed, it does not meet the connection requirements between the flexible fabric antenna and the communication equipment in actual wearable applications and the requirements of the actual deployment location.

[0010] In summary, as ad hoc network radio antennas develop towards wearable and flexible trends, it is necessary to solve the problems that low frequencies and large wavelengths are difficult to apply under low-profile and small space conditions, the low profile causes a significant reduction in antenna efficiency and performance, and the current flexible fabric antennas fail to meet connection and deployment requirements in actual applications. Summary of the invention

[0011] In view of the current problems of the above-mentioned fabric antennas for self-organizing radio stations, the present invention provides a fabric antenna for self-organizing radio stations based on a defective ground structure. By setting a defective ground structure with the same size as the top conductive layer at the bottom of the intermediate dielectric layer, the problem of low frequency and large wavelength being difficult to apply under low profile and small space conditions, the problem that the low profile causes a significant reduction in antenna efficiency and performance, and the problem that the current flexible fabric antenna fails to meet the connection, deployment and reliability requirements in practical applications is solved. The specific contents are as follows:

[0012] A fabric antenna for a self-organizing radio station based on a defective ground structure, comprising a top conductive layer, an intermediate dielectric layer and a bottom conductive layer;

[0013] The top conductive layer is a square ring structure with a cut corner;

[0014] The bottom conductive layer is a square thin sheet structure with a square defect in the middle;

[0015] The width dimension W of the defect DGS The top conductive layer width dimension W patch equal;

[0016] The intermediate dielectric layer is a flexible fabric material, and the top surface and the bottom surface are correspondingly bonded and connected to the top conductive layer and the bottom conductive layer.

[0017] Furthermore, the center points of the defective ground and the top conductive layer coincide with each other and their edges are arranged in parallel.

[0018] Further, the top conductive layer includes a microstrip port, a feed line and a radiating structure;

[0019] The microstrip port, feeder and radiation structure are an integrated structure;

[0020] The feed line is arranged at the edge of the radiation structure;

[0021] The microstrip port is arranged at an end of the feed line away from the radiation structure.

[0022] Furthermore, the microstrip port adopts a side microstrip feeding structure;

[0023] The radiation structure is a square ring structure, and a right angle at a corresponding position of an outer edge and an inner edge and away from the feeder line is in a 45° cut shape.

[0024] Furthermore, the internal open loop area of ​​the radiation structure is ≤ 2 / 3 times the total area of ​​the radiation structure.

[0025] Furthermore, the intermediate medium layer is made of nylon fabric material.

[0026] Furthermore, the top conductive layer and the bottom conductive layer may be made of copper, silver, gold or graphene materials.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention realizes the flexible design of the antenna by arranging a thin sheet-shaped conductive layer on the flexible fabric. The present invention is applied to a self-organizing network radio station. Compared with the existing rod-shaped or whip-shaped self-organizing network radio station antenna, the problems of cable hooking, influence on limb movement and complex structure can be solved;

[0029] 2. The present invention sets a square defect ground with leakage wave and slow wave effect at the bottom of the intermediate dielectric layer, which can effectively improve the working efficiency of the antenna and reduce the antenna frequency, thereby improving the antenna performance while reducing the antenna size;

[0030] 3. The present invention fixes the top conductive layer and the bottom conductive layer on the top and bottom surfaces of the intermediate dielectric layer by a bonding connection method to achieve a higher gain with an extremely low profile, reaching the typical gain level of a self-organizing radio antenna; compared with other flexible circularly polarized fabric antennas, it has higher technical maturity, solves the problems of connection, deployment and reliability of self-organizing radio fabric antennas in practical applications, and realizes self-organizing radio communication under wearable applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative work.

[0032] Figure 1 This is the three-dimensional structural layout diagram of the fabric antenna of the ad hoc network radio station;

[0033] Figure 2 It is a front view of the planar structure layout of the fabric antenna of the ad hoc network radio station;

[0034] Figure 3 It is a bottom view of the planar structure layout of the fabric antenna of the ad hoc network radio station;

[0035] Figure 4 This is a test diagram of the effect of the cutting angle size of the fabric antenna radiation structure on the circular polarization level of the ad hoc radio station;

[0036] Figure 5 The influence of feeder width of fabric antenna on antenna impedance matching for ad hoc radio stations;

[0037] Figure 6 The effect of feed line length on antenna impedance matching of fabric antenna for ad hoc radio stations;

[0038] Figure 7 The relationship between the width dimension of the fabric antenna radiation structure of the ad hoc radio station and the antenna frequency;

[0039] Figure 8 The relationship between the window size and gain of the fabric antenna radiation structure for ad hoc radio stations;

[0040] Fig. 9 CMSA simulation results of the fabric antenna for the ad hoc radio station (a) are the S parameters and gain, and (b) are the 2D radiation patterns.

[0041] Fig.10 The current distribution on the surface of the fabric antenna of the ad hoc network radio station;

[0042] Fig.11 Three different antenna structures and current distributions: (a) microstrip patch antenna, (b) DGS fabric antenna, and (c) planar monopole antenna.

[0043] Fig.12 Antenna S parameter and gain curves under different DGS width sizes, (a) is the S parameter change curve, (b) is the gain change curve;

[0044] Fig.13 For different DGS width dimensions W DGSThe fitting curve corresponding to the antenna resonant frequency;

[0045] In the figure: 1. top conductive layer; 101. cut corner; 102. feed line; 103. microstrip port; 104. radiation structure; 2. middle dielectric layer; 3. bottom conductive layer; 301. defective ground. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0048] It should be noted that when an element is referred to as being "fixed to", "placed on", "disposed with", "provided with", "set to", "arranged to" or "connected to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0049] It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] The following is combined with Figures 1 to 13 The present invention is described in detail with specific embodiments:

[0051] A fabric antenna for a self-organizing radio station based on a defective ground structure, such as Figure 1 , Figure 2As shown, it includes a top conductive layer 1, an intermediate dielectric layer 2 and a bottom conductive layer 3;

[0052] The top conductive layer 1 is a square ring-shaped thin sheet structure having a cut corner 101;

[0053] The bottom conductive layer 3 is a square thin sheet structure with a square defect 301 in the middle;

[0054] like Figure 2 , Figure 3 As shown, the width dimension W of the defect 301 is DGS The top conductive layer 1 has a width W patch equal;

[0055] The intermediate dielectric layer 2 is a flexible fabric material, and the top surface and the bottom surface are correspondingly bonded and connected to the top conductive layer 1 and the bottom conductive layer 3 .

[0056] like Figure 3 As shown, the center points of the defective ground 301 and the top conductive layer 1 coincide with each other and their edges are arranged in parallel.

[0057] It should be noted that the bottom conductive layer 3 is provided with a defective ground structure 301 (Defected Ground Structure, English abbreviation: DGS), which can play a role in leakage wave and slow wave effects; the leakage wave effect is used to improve the low efficiency caused by the thin medium, and the slow wave effect is used to reduce the antenna operating frequency, thereby improving the antenna performance and reducing the antenna size.

[0058] In a specific implementation, the present invention realizes a flexible design of the antenna by arranging a thin sheet-like conductive layer on a flexible fabric. The present invention is applied to a self-organizing radio station. Compared with the existing rod-shaped or whip-shaped self-organizing radio station antenna, the problems of cable hooking, affecting limb movement and complex structure can be solved; the present invention arranges a square defect ground 301 with leakage wave and slow wave effects on the bottom layer of the intermediate dielectric layer 2, which can effectively improve the antenna working efficiency and reduce the antenna frequency, thereby improving the antenna performance while reducing the antenna size; the present invention fixes the top conductive layer 1 and the bottom conductive layer on the top and bottom surfaces of the intermediate dielectric layer 2 by a bonding connection method to achieve a higher gain under an extremely low cross-section, reaching the typical gain level of the self-organizing radio station antenna; compared with other flexible circularly polarized fabric antennas, it has a higher technical maturity and realizes self-organizing radio station communication under wearable applications.

[0059] In the embodiment provided by the present invention, Figure 1 , Figure 2 As shown, the top conductive layer 1 includes a microstrip port 103, a feed line 102 and a radiation structure 104;

[0060] The microstrip port 103, the feed line 102 and the radiation structure 104 are an integrated structure;

[0061] The feed line 102 is disposed at the edge of the radiation structure 104;

[0062] The microstrip port 103 is disposed at an end of the feed line 102 away from the radiation structure 104;

[0063] The microstrip port 103 adopts a side microstrip feeding structure;

[0064] The radiation structure 104 is a square ring structure, and a right angle at the corresponding position of the outer edge and the inner edge and away from the feed line 102 is in the shape of a 45° cut angle 101;

[0065] The internal open loop area of ​​the radiation structure 104 is ≤ 2 / 3 times of the total area of ​​the radiation structure 104 .

[0066] It should be noted that there are two feeding methods for the microstrip port 103, one is side microstrip feeding, that is, the microstrip port 103 and the feed line 102 are in the same plane with the radiation structure 104; the other is bottom microstrip feeding, that is, the outer conductor of the coaxial line is directly connected to the bottom conductive layer 3, and the inner conductor passes through the bottom conductive layer 3 and the intermediate dielectric layer 2 to connect with the radiation structure 104; since the intermediate dielectric of the present invention adopts a flexible fabric material, if bottom microstrip feeding is adopted, when the coaxial line passes through the intermediate dielectric layer 2, it is necessary to additionally set a metal through hole on the fabric to ensure that the fabric and the stability of the connection are not damaged; therefore, the feeding method of the fabric antenna provided by the present invention preferably adopts side microstrip feeding, which can avoid the inner conductor of the coaxial line passing through the bottom conductive layer 3 and the intermediate dielectric layer 2, thereby ensuring the high flexibility and low processing complexity of the fabric antenna.

[0067] It should be noted that in order to overcome the polarization mismatch problem of wearable devices, ad hoc network radio stations usually adopt circularly polarized electromagnetic waves; and the synthesis of circular polarization of electromagnetic waves relies on the superposition of two resonant modes with a phase difference of 90°; the present invention can separate the original resonant mode of the antenna into two resonant modes with a phase difference of 90° by providing a 45° cut angle 101 at a corner of the radiation structure 104 away from the feed line 102; therefore, by setting a 45° cut angle 101 in the radiation structure 104, the resonance can be separated and the phase difference can be caused to realize the circular polarization of the electromagnetic wave.

[0068] It should be noted that the present invention preferably designs specific parameters and structures for a 1.37 GHz ad hoc network radio station, and takes 1.37 GHz as the midpoint and performs simulation tests within a certain range thereof to obtain the following relevant data; for ad hoc network radio stations of other operating frequencies, the technical solutions in this specification may be referred to for design.

[0069] It should be noted that the length W of the right angle side of the cut corner 101 is chamfer Determines the level of circular polarization; e.g. Figure 4 As shown, the axial ratio of the radiation structure 104 with a cutting angle 101 of 12 mm to 16 mm is tested. In the range of 1.35 to 1.39 GHz, it can be seen that the smaller the cutting angle 101 is, the lower the axial ratio is, and the lower the axial ratio is, the better the circular polarization level is. The preferred embodiment of the present invention is W chamfer The size is 14mm.

[0070] It should be noted that the width W of the feed line 102 is feed and length L feed The antenna impedance matching can be adjusted to improve signal transmission efficiency; Figure 5 Shows W feed Impedance matching curve when the value is 0.6mm~1.4mm; Figure 6 Shows L feed The impedance matching curve when the value is 1.0mm~9.0mm; the preferred embodiment of the present invention is W feed Size: 1mm, L feed The size is 5mm.

[0071] The width dimension W of the square ring structure of the radiation structure 104 is patch (i.e. the width of the top conductive layer 1) determines the working frequency of the antenna, and can be adjusted according to the different frequencies of the ad hoc network radio station. patch The value of Figure 7 Shown is W patch When the value is 47mm~49mm, the frequency change of the corresponding ad hoc network radio station is; the preferred embodiment of the present invention is W patch The size is 48mm.

[0072] It should be noted that the window can be opened to W without affecting the antenna performance. patch1 size; fabric antennas are used in wearable communications due to their soft texture; the present invention proposes to design the radiation structure 104 as a ring structure without affecting the performance of the self-organizing network fabric antenna, that is, to open the loop inside the radiation structure 104; the purpose of the open loop is to make the overall fabric antenna have better softness and smaller mass; after testing fabric antennas with different open loop sizes, such as Figure 8 As shown, near 1.37 GHz to 1.39 GHz, it can be seen that the open loop size has no significant effect on the gain of the ad hoc network radio signal, so the open loop size can be increased under the premise of ensuring the strength of the radiation structure 104; it is recommended that the open loop area is ≤ 2 / 3 times the total area of ​​the radiation structure 104, which can ensure the strength of the radiation structure 104 and ensure a good gain effect; the preferred open loop side length size W of the present invention is patch1 It is 34mm.

[0073] In a specific implementation, the present invention adopts a side microstrip feeding connection method, which can avoid setting metal through holes in the bottom conductive layer 3 and the intermediate dielectric layer 2, thereby reducing the processing difficulty of the fabric antenna and improving the flexibility of the fabric antenna; applying this connection method solves the connection problem of flexible antennas in practical applications, and enables the fabric antenna to be more flexibly deployed on the human body; the radiation structure 104 adopts a ring structure, and the open loop area is ≤2 / 3 times the total area of ​​the radiation structure 104, which can ensure a good gain effect while ensuring the antenna performance and strength.

[0074] In one embodiment, the intermediate medium layer 2 is made of nylon fabric material.

[0075] It should be noted that the present invention preferably uses high-performance nylon fabric with properties such as light weight, high strength, wear resistance and flame retardancy as the intermediate dielectric layer 2 of the fabric antenna; the single-layer thickness of this nylon fabric does not exceed 0.4 mm, and it is woven from high-strength nylon 66 yarn. It is the main fabric of a carrying vest that carries smart wearable devices such as handheld ad hoc network radio stations, and has good physical properties such as light weight, high strength, wear resistance and flame retardancy, and can better adapt to general and special wearable applications.

[0076] Compared with film materials, fabric materials have stronger flexibility, that is, they have greater thickness while maintaining a smaller bending radius; this is because the fabric introduces a periodic pore structure during the textile preparation process, which gives it a certain elasticity in the thickness direction; and nylon yarn is made of multiple high-strength nylon fibers, and the surface has a high flatness; as the price of high flexibility, the nylon material with introduced pores can be regarded as a composite material formed by an ideal dense nylon material and air; as the composite air increases, the dielectric constant of the material decreases and the loss tangent increases; the structure and proportion of the composite air depend on the yarn and textile process parameters of the nylon fabric material.

[0077] The dielectric constant of the high-strength nylon fiber in the present invention was measured by the resonant cavity method to be 2.0 and the loss tangent of the nylon fabric to be 0.019. The dielectric constant and loss tangent of different fabric media as the base of the fabric antenna are different; in simple terms, the larger the dielectric constant, the smaller the antenna size; the larger the loss tangent, the lower the antenna efficiency and the corresponding gain. Therefore, based on the technical solution provided by the present invention, fabrics of different materials can be used according to actual needs for the intermediate dielectric layer 2 of the fabric antenna of the self-organizing network radio station, such as fabric materials such as polyester or aramid.

[0078] In a specific implementation, the present invention uses high-performance nylon fabric as the intermediate dielectric layer 2 of the fabric antenna, so that the fabric antenna of the ad hoc network radio station has good physical properties such as high strength, light weight, and high flexibility.

[0079] In the embodiment provided by the present invention, the top conductive layer 1 and the bottom conductive layer 3 may be made of copper, silver, gold or graphene materials.

[0080] It should be noted that copper, silver, gold and graphene materials all have good electrical conductivity and can efficiently transmit signals. Therefore, the above materials can be selected as the conductive layer material of the fabric antenna according to different needs; the present invention preferably uses a copper conductive layer to achieve low cost while ensuring that the antenna has good performance.

[0081] The purpose of the present invention is to improve the performance of the fabric antenna of the self-organizing radio station by designing and improving the structure of the fabric antenna of the self-organizing radio station. In the prior art, additive structural designs such as arrays, parasitic patches, branches, and super surfaces are all to improve the antenna performance by adding antenna structures, which will undoubtedly lead to an increase in the profile thickness and antenna area, which is inconsistent with the original design intention of the present invention to reduce the antenna size and improve the antenna performance at the same time. The subtractive structural design such as opening holes, slots, and slits on the radiation structure 104 of the antenna can overcome the problem of increasing the antenna size, but will lead to a decrease in antenna efficiency and gain. The defective ground structure adopted by the present invention is a subtractive structural design designed on the bottom conductive layer 3; that is, by changing the current distribution on the bottom conductive layer 3, the performance improvement such as expanding the bandwidth, reducing the antenna size, and increasing the gain can be achieved in the cavity resonant antenna under extremely low profile. After simulation and testing, it was found that the introduction of DGS can minimize the impact on the radiation structure 104, and can become the best improved structure for high-performance ultra-low profile flexible wearable fabric antennas.

[0082] like Figure 1 to Figure 3 As shown, compared with the microstrip patch antenna, the DGS-based antenna has a square window on the bottom conductive layer 3, i.e., a DGS structure. DGS can improve the gain of the very low profile antenna through the leakage wave effect while reducing the size of the antenna through the slow wave effect. The position of the DGS is the same as that of the radiation structure 104, and the different DGS sizes W DGS Determines the gain and miniaturization of the antenna. The key size parameters of the optimized 1.4GHz circularly polarized DGS fabric antenna are shown in Table 1. The overall size of the antenna is 70×70×0.4mm 3 , which is equivalent to

[0083] Table 1 Key dimensions of fabric antennas for ad hoc radio stations Unit: mm

[0084]

[0085] The simulation results of the self-organizing network fabric antenna provided by the present invention are as follows: Fig. 9 shown. Fig. 9(a) shows the simulated S parameters and maximum gain of the antenna. The frequency range of S11<-10dB is 1.30~1.61GHz, the impedance bandwidth is 310MHz, the relative bandwidth is 21.3%, the maximum gain is 3.5dBi@1.37GHz, and the gain is greater than 3dBi in the frequency range of 1.30~1.74GHz. Fig. 9 (b) shows the radiation pattern at 1.37 GHz. The maximum radiation pointing angles are 0° and 180°. The E-plane and H-plane radiation patterns are consistent, showing good radiation characteristics.

[0086] Compared with the microstrip patch antenna, the overall size (side length) of the DGS-based fabric antenna is only 60% of the original (the two sides are 64% and 56% respectively), the bandwidth is expanded by 16.9%, and the gain is increased by 5.6dB. While miniaturizing, the antenna's gain, bandwidth and other performance have been greatly improved.

[0087] The far-field electromagnetic fields E and H in the direction can be calculated by integrating the current source J(r′).

[0088]

[0089] Where μ and ε represent the magnetic permeability and dielectric constant respectively, R represents the distance between the source point r′ and the observation point r, and A r , A θ , Respectively represent the introduced vector position A along directional component, and k is the wave number.

[0090] like Fig.10 As shown in Figure 1, the surface current distribution of the antenna at 0°, 90°, 180°, and 270° phases at 1.37 GHz is shown. The surface current of the antenna is concentrated at the edge of the patch and the DGS window, and rotates clockwise within the phase period to form circular polarization.

[0091] The analysis of DGS fabric antennas mainly relies on the analysis of structure and surface current. Compare the structures of the cut-angle microstrip patch antenna, DGS fabric antenna and planar monopole antenna, such as Fig.11 As shown in the figure, the structural differences between the three are mainly due to the shape change of the bottom conductive layer. The DGS fabric antenna can be regarded as an intermediate structure between the microstrip patch antenna and the planar monopole antenna. Different from the microstrip patch antenna (MSA), the radiation structure and ground projection of the DGS fabric antenna and the planar monopole antenna (MNA) are complementary, and the surface current at the edge of the radiation structure is in the opposite direction, as shown in the figure. Fig.11As shown by the red and black arrows in the figure. Furthermore, compared with the microstrip patch antenna, the DGS fabric antenna relies on the circular DGS with a window in the middle to achieve the leakage wave and slow wave effects without changing the current distribution of the radiation structure. This means that although the DGS fabric antenna has a near-omnidirectional radiation similar to the planar monopole antenna, it is different from the planar monopole antenna in that it can retain special designs such as circular polarization achieved by perturbation structures such as corner cutting and slotting on the DGS fabric antenna, and its directivity is also stronger.

[0092] The leakage wave characteristics of the DGS fabric antenna are due to the fact that the window below the radiation structure destroys the cavity resonance structure and reduces the Q value, which is the key to improving efficiency and gain under extremely low profile conditions. The back open structure introduces the connection between the antenna and the external space, forming a larger equivalent resonant cavity of the composite medium and air, thereby reducing the operating frequency of the antenna and achieving slow wave characteristics. The reduction of the antenna Q value also further expands the antenna bandwidth.

[0093] like Fig.12 As shown, different DGS width dimensions W are shown. DGS The antenna S parameters and gain. In the range of 20 to 48 mm, as the DGS width increases, the antenna resonant frequency decreases, and the bandwidth and gain increase. DGS Greater than 48mm (48mm is the width of the radiation structure determined by the operating frequency of the ad hoc network radio station patch ), according to Fig.12 (a) The S parameters of the antenna show that the dual resonance characteristics of the antenna disappear, and it presents broadband characteristics similar to those of a planar monopole antenna. Fig.12 (b) The antenna gain no longer increases, but instead shows a slight decrease as the directivity decreases. This shows that the DGS fabric antenna with the same DGS width as the radiating structure width has the advantages of broadband and miniaturization, and has a higher gain than the microstrip patch antenna and the planar monopole antenna, making it the best antenna for extremely low profiles.

[0094] Using the above conclusions, the key dimensions of the DGS fabric antenna under different ad hoc network radio frequencies can be calculated: W DGS (equivalent to determining the width dimension W of the radiation structure patch ). The design of flexible wearable antenna is mainly based on miniaturized side-fed antenna. Miniaturization constrains the size of the intermediate dielectric layer. The side microstrip feeding structure increases the length of the intermediate dielectric layer, so the side microstrip feeding width W substrate Usually does not exceed the side microstrip feed length L substrate For DGS fabric antenna, the DGS width dimension W DGS is smaller than the size of the intermediate dielectric layer. At this time, W DGSThe valid value range of is:

[0095] 0 <W DGS <W substrate ≤L substrate (4)

[0096] When W DGS When the value is 0, the DGS window disappears, corresponding to the structure of the microstrip patch antenna, the resonant frequency is:

[0097]

[0098] Where c is the speed of light; m, n represent the resonant modes respectively, and (m, n) = (0, 1) in Equation 5; the equivalent dielectric constant ε of the low-profile antenna eff The relative dielectric constant ε of the material can be directly taken r .

[0099] When W DGS When the maximum value is reached, the DGS ring feature disappears, and only the ground below the feeding position is retained, corresponding to the structure of a planar monopole antenna; the resonant frequency is:

[0100]

[0101] In W DGS The effective range, based on the resonant frequency of the DGS fabric antenna can be expressed as:

[0102]

[0103] Among them, F(W DGS ) is the size W of DGS DGS The factor function of . Fig.13 As shown, W DGS The simulated resonant frequency in the effective range shows that as W DGS As the frequency increases, the antenna resonant frequency continues to decrease.

[0104] The DGS fabric antenna proposed in this invention is based on a large number of different W DGS The resonant frequency change curve obtained by simulation test ( Fig.13 ), and then the DGS size factor function is fitted by a third-order polynomial, and the expression is:

[0105] F(W DGS )=-2.205×10 -5 W DGS 3 +2.737×10 -3 W DGs 2 -0.122W DGS +3.369 (8)

[0106] Substituting the calculated results into Formula 7, the key dimensions of the DGS fabric antenna at different operating frequencies can be obtained.

[0107] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0108] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A fabric antenna for a self-organizing radio station based on a defective ground structure, characterized in that: It includes a top conductive layer, an intermediate dielectric layer and a bottom conductive layer; The top conductive layer is a square ring-shaped thin sheet structure with a cut corner; The bottom conductive layer is a square thin sheet structure with a square defect in the middle; The width dimension W of the defect DGS The top conductive layer width dimension W patch equal; The intermediate dielectric layer is a flexible fabric material, and the top surface and the bottom surface are correspondingly bonded and connected to the top conductive layer and the bottom conductive layer.

2. The fabric antenna for ad hoc radio stations based on defective ground structures according to claim 1 is characterized in that: The center point of the projection of the defective land on the intermediate dielectric layer coincides with the center point of the top conductive layer; and the edge of the projection is parallel to the edge of the top conductive layer.

3. The fabric antenna for ad hoc network radio station based on defective ground structure according to claim 1, characterized in that: The top conductive layer includes microstrip ports, feed lines and radiating structures; The microstrip port, feeder and radiation structure are an integrated structure; The feed line is arranged at the edge of the radiation structure; The microstrip port is arranged at an end of the feed line away from the radiation structure.

4. The fabric antenna for ad hoc network radio station based on defective ground structure according to claim 3 is characterized in that: The microstrip port adopts a side microstrip feeding structure; The radiation structure is a square ring structure, and a right angle at a corresponding position of an outer edge and an inner edge and away from the feeder line is in a 45° cut shape.

5. The fabric antenna for ad hoc radio stations based on defective ground structures according to claim 4 is characterized in that: The internal open loop area of ​​the radiation structure is ≤ 2 / 3 times the total area of ​​the radiation structure.

6. The fabric antenna for ad hoc network radio station based on defective ground structure according to claim 1, characterized in that: The middle medium layer is made of nylon fabric material.

7. The fabric antenna for ad hoc network radio station based on defective ground structure according to claim 1, characterized in that: The top conductive layer and the bottom conductive layer may be made of copper, silver, gold or graphene material.

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