Edge-emitting gain enhanced dual-frequency dual-mode fabric antenna

Abstract

The invention discloses a double-frequency dual-mode fabric antenna with enhanced edge emission gain. The double-frequency dual-mode fabric antenna comprises a radiation patch, an antenna dielectric substrate and an antenna floor, the radiation patch is attached to the upper surface of the antenna dielectric substrate, and the antenna floor is attached to the lower surface of the antenna dielectric substrate; wherein a symmetrical side of the radiation patch is respectively provided with a gain improving gap, the other side of the radiation patch extends outwards to form a microstrip feeder line, impedance matching gaps are respectively arranged between two sides of the microstrip feeder line and the radiation patch, and the antenna adopts a scheme of a microstrip line side-fed square microstrip patch antenna. The flexible wearable dual-frequency dual-mode antenna is simple in structure, meets the requirements of an on-body communication mode, is very small in-band gain fluctuation, is obviously higher than an existing flexible wearable dual-frequency dual-mode antenna in edge emission gain under the condition of guaranteeing the simple structure, and effectively improves the communication quality of an in-body communication mode.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to a dual-frequency dual-mode fabric antenna with enhanced side-fire gain. Background Art

[0002] Wearable antennas are worn directly on the wearer's body, so they need to consider not only the impact of the human body's load effect on the antenna's radiation performance and radiation safety, but also the wearing comfort. In addition, flexible wearable antennas also need to solve the conformal ability when deformed due to close proximity to the human body. Depending on the communication object, wearable devices need to implement two communication modes. The first communication mode is on-body communication between wearable devices. The characteristic of this communication mode is that all wearable devices communicate with each other with the human body as the center. Therefore, the designed antenna requires that the radiation pattern should be an omnidirectional radiation mode to ensure good communication coverage. The second communication mode is off-body communication between wearable devices and external communication networks. This communication mode requires that the wearable antenna should have a directional radiation pattern. Due to the uncertainty of the distance change between the wearer and the external communication device, in order to ensure a good communication connection, an important development direction of wearable antennas for off-body communication mode is the design of high-gain directional radiation antennas. Therefore, in order to meet the two communication modes of wearable devices while ensuring the wearing comfort and conformal capability of flexible wearable antennas, as well as to ensure the communication quality of off-body communication, a dual-band dual-mode fabric antenna with directional radiation / side-fire gain enhancement characteristics is an ideal solution. That is, based on the fabric antenna, the antenna can work in two frequency bands at the same time, and the two frequency bands have omnidirectional radiation patterns and directional radiation patterns respectively, so as to meet both on-body communication and off-body communication working modes.

[0003] The existing dual-band dual-mode wearable antennas mainly use multi-radiator design and metamaterial-loaded design, which significantly increase the complexity of antenna design and processing as well as the complexity of antenna assembly. Therefore, their actual application value is low, and their directional radiation gain is generally 4-7dBi, which is difficult to meet the demand for directional radiation gain in the above scenarios. Most of the existing high-gain technologies use array technology, multi-patch technology, loaded AMC technology, etc., which will also increase the complexity of antenna design, increase antenna profile and size, and have higher processing requirements. Therefore, these solutions are not suitable for the design of low-cost, simple-structure wearable fabric antennas. Summary of the invention

[0004] Based on this, in order to solve the above problems, the present application provides a dual-frequency dual-mode fabric antenna with enhanced side-firing gain. 00The mode achieves omnidirectional radiation in the 2.45 GHz band, and the TM is suppressed by designing symmetrical slots on both sides of the antenna. 30 The mode side lobe achieves a high-gain side-fire radiation mode in the 5.8Ghz frequency band. The antenna is made of fabric materials such as conductive cloth and wool felt. Compared with existing related research, it has a simple structure, no complex feeding network, is easy to process and manufacture, and the dual frequencies can be tuned independently, and the side-fire gain is significantly improved.

[0005] A dual-frequency dual-mode fabric antenna with enhanced side-fire gain, comprising:

[0006] Radiating patch, antenna dielectric substrate, and antenna floor;

[0007] The upper surface of the antenna dielectric substrate is attached to the radiation patch, and the lower surface of the antenna dielectric substrate is attached to the antenna floor;

[0008] A gain improvement slot is provided on each symmetrical side of the radiation patch, and the other side of the radiation patch extends outward to form a microstrip feed line. Impedance matching slots are provided on both sides of the microstrip feed line and between the radiation patch.

[0009] In one of the embodiments, the radiation patch, the antenna dielectric substrate, and the antenna ground are attached to each other.

[0010] In one embodiment, the radiation patch, the antenna dielectric substrate, and the antenna floor are all provided with rivet holes, and also include hollow rivets, and the radiation patch, the antenna dielectric substrate, and the antenna floor are connected by the hollow rivets to realize the TM of the excitation antenna. 00 model.

[0011] In one of the embodiments, the hollow rivet is made of brass, has an outer diameter of 2.2 to 3.5 mm, and there are at least two hollow rivets symmetrically arranged along the center of the radiation patch.

[0012] In one of the embodiments, there are four hollow rivets, and the ratio of the spacing between any two adjacent hollow rivets parallel to the edge of the radiation patch to the edge length of the radiation patch is 0.66-0.88.

[0013] In one of the embodiments, the radiation patch and the antenna floor are made of conductive cloth.

[0014] In one of the embodiments, the antenna dielectric substrate is wool felt, with a relative dielectric constant of 1.2, a loss tangent of 0.03, a thickness of 0.02λ0, and a length and width of 0.78λ0.

[0015] In one embodiment, the radiation patch is square, and the ratio of the length of the gain-enhancing slot to the length of the radiation patch is 0.18-0.20.

[0016] In one of the embodiments, the length of the microstrip feed line is 16.5±2 mm and the width is 9±1 mm.

[0017] In one embodiment, the impedance matching gap has a length of 12±2 mm and a width of 5±1 mm, and the total length of the microstrip feed line after calculating the gap length is 0.23λ0.

[0018] Beneficial effects of this application:

[0019] 1. The antenna uses a microstrip patch antenna with microstrip line side feeding, and the TM of the antenna is excited by loading a hollow rivet. 00 mode, achieving omnidirectional radiation mode in the 2.45 GHz frequency band to meet the needs of on-body communication. Gain-enhancing slots are designed at symmetrical positions on both sides of the antenna to suppress TM 30 mode side lobes to achieve high-gain side-fire radiation mode to meet the needs of off-body communication.

[0020] 2. Hollow rivets are designed in TM 30 mode near the electric field zero point, which is used to reduce its effect on TM 30 The gain-enhancing slots are designed symmetrically on both sides of the square patch antenna, parallel to the TM 00 mode current position, used to reduce its TM 00 The frequency and directional pattern of the mode are affected, thereby achieving independent adjustment of dual frequencies.

[0021] 3. The antenna adopts a microstrip line side-feeding feeding scheme and uses a pair of gaps at the connection between the microstrip line and the antenna for impedance matching, ensuring the advantage of a simple antenna feeding network structure.

[0022] 4. The radiation patch and floor of the antenna are made of conductive cloth, and the dielectric substrate is wool felt, which can effectively increase the wearing comfort and conformal ability of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the antenna structure of an embodiment of the present application;

[0024] Figure 2 This is a top view of an antenna according to an embodiment of the present application;

[0025] Figure 3 This is a schematic diagram of the three-dimensional structure of an antenna according to an embodiment of the present application;

[0026] Figure 4 is a graph of the reflection coefficient of the antenna as it changes with frequency;

[0027] Figure 5Normalized radiation pattern at 2.45GHz, phi=0°, theta=0°;

[0028] Figure 6 Normalized radiation pattern at 2.45GHz, phi=90°, theta=0°;

[0029] Figure 7 Normalized radiation pattern at 2.45GHz, phi=0°, theta=90°;

[0030] Figure 8 Normalized radiation pattern at 5.8 GHz, phi = 0°, theta = 0°;

[0031] Fig. 9 Normalized radiation pattern at 5.8GHz, phi=90°, theta=0°;

[0032] Fig.10 is a graph showing the gain of the antenna changing with frequency;

[0033] Fig.11 TM when no rivet is loaded 30 Scalar plot of the electric field distribution. DETAILED DESCRIPTION

[0034] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0035] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply 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 a limitation on the present application.

[0036] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0037] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated 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, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0038] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0039] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0040] Wearable antennas are worn directly on the wearer's body, so they not only need to consider the impact of the human body's load effect on the antenna's radiation performance and radiation safety, but also the wearing comfort. In addition, flexible wearable antennas also need to solve the problem of conformal ability when deformed due to close contact with the human body. Depending on the communication object, wearable devices need to implement two communication methods.

[0041] This embodiment provides a dual-frequency dual-mode fabric antenna with enhanced side-firing gain. The hollow rivet 5 is loaded with a brass rivet as a short-circuit nail to excite the TM of the microstrip patch antenna. 00 The mode achieves omnidirectional radiation in the 2.45 GHz band, and the TM is suppressed by designing symmetrical slots on both sides of the antenna. 30 The mode side lobe achieves a high-gain side-fire radiation mode in the 5.8Ghz frequency band. The antenna is made of fabric materials such as conductive cloth and wool felt. Compared with existing related research, it has a simple structure, no complex feeding network, is easy to process and manufacture, and the dual frequencies can be tuned independently. The side-fire gain is significantly improved. Its specific structure is as follows:

[0042] See also Figure 1 , Figure 1 A dual-band dual-mode fabric antenna with enhanced side-fire gain in one embodiment of the present application is shown, the antenna comprising a radiation patch 1, an antenna dielectric substrate 6, and an antenna floor 7; the upper surface of the antenna dielectric substrate 6 is bonded to the radiation patch 1, and the lower surface of the antenna dielectric substrate 6 is bonded to the antenna floor 7; wherein a gain-enhancing slot 2 is provided on each symmetrical side of the radiation patch 1, the other side of the radiation patch 1 extends outward to form a microstrip feed line 4, and impedance matching slots 3 are provided on both sides of the microstrip feed line 4 and between the radiation patch 1.

[0043] refer to Figure 2 In the final bonded antenna, the end of the microstrip feed line 4 is flush with the edges of the antenna dielectric substrate 6 and the antenna floor 7. Specifically, the sizes of the antenna dielectric substrate 6 and the antenna floor 7 match, or the sizes and shapes of the antenna dielectric substrate 6 and the antenna floor 7 are exactly the same. The size of the radiation patch 1 is smaller than the antenna dielectric substrate 6 and the antenna floor 7, and is located at the center of the antenna dielectric substrate 6 and the antenna floor 7. The microstrip feed line 4 extends from the inside to the outside until it is flush with the edges of the antenna dielectric substrate 6 and the antenna floor 7.

[0044] In this embodiment, the antenna adopts a microstrip patch antenna structure with a microstrip feed line 4 feeding sideways, and the TM of the antenna is excited by loading a hollow rivet 5. 00 mode, achieving omnidirectional radiation mode in the 2.45 GHz frequency band to meet the needs of on-body communication. Gain-enhancing slots 2 are designed at symmetrical positions on both sides of the antenna to suppress TM 30 mode sidelobes, achieving high-gain side-fire radiation mode to meet the needs of off-body communication. Hollow rivet 5 is designed in TM 30 mode near the electric field zero point, which is used to reduce its effect on TM 30 The gain enhancement slot 2 is designed symmetrically on both sides of the square radiation patch 1 and parallel to the TM 00 mode current position, used to reduce its TM 00The frequency and directional pattern of the mode are affected, so that the dual-frequency can be adjusted independently. The antenna adopts a microstrip line side-feeding feeding scheme, and uses a pair of gaps at the connection between the microstrip line and the antenna for impedance matching, ensuring the advantage of a simple antenna feeding network structure.

[0045] In one embodiment, the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7 are bonded together by means of a conductive cloth with double-sided adhesive tape. Figure 1 As shown, rivet holes 8 are provided on the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7, and the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7 are attached by hollow rivets 5 to realize the TM of the excitation antenna. 00 model.

[0046] It should also be noted that the bonding methods in other embodiments are not unique, and the bonding materials and bonding order can be changed accordingly to meet functional requirements. For example, the radiation patch and the floor are both conductive cloth with double-sided adhesive, which are directly pasted on the dielectric substrate, or different layers of materials are fastened with rivets or bayonet fasteners.

[0047] In one embodiment, the hollow rivet 5 is made of brass, and its outer diameter is 3.5 mm. There are at least two hollow rivets 5 arranged symmetrically along the center of the radiation patch 1. In a specific embodiment, the outer diameter of the hollow rivet 5 is 3.5 mm, there are four hollow rivets 5, and they are arranged symmetrically along the center of the radiation patch 1. For example, in this embodiment, the radiation patch 1 is a square with four sides, and there are at least four hollow rivets 5.

[0048] It is worth noting that, in addition to the square radiation patch 1, a circular radiation patch can be used. 21 Mode (There is a difference in the naming of the working mode between the circular patch and the rectangular patch. The TM 21 The pattern corresponds to the TM of the rectangular patch 30 The omnidirectional radiation mode TM can also be stimulated by placing a short-circuit nail at the zero point of the electric field 01 Die (corresponding to the TM of the square patch 00 module) and does not affect TM 21 model.

[0049] The number, location and size of rivets will affect TM to a certain extent. 00 The resonant frequency of the mode, while keeping the 4 rivets unchanged, the larger the size of the rivets, the higher the TM 00 The higher the resonant frequency of the mode, the smaller the size of the rivet TM 00 The lower the resonant frequency of the mode. In this embodiment, rivets with an outer diameter of 3.5 mm are used to adjust the resonant frequency to the target operating frequency band. Four rivets are used mainly because the current of the rivets on both sides of the gain-enhancing gap 2 is in the TM00 The mode is parallel to the gap, so the length of the gap has almost no effect on TM 00 The resonant frequency of the mode.

[0050] More specifically, in one embodiment, the four hollow rivets 5 are made of brass, and the ratio of the distance between any two adjacent hollow rivets 5 parallel to the edge of the radiation patch 1 to the edge length of the radiation patch 1 is 0.74. Figure 1 As shown, the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7 are each provided with four rivet holes 8, and the positions of the rivet holes 8 correspond to each other. When the rivet holes 8 at corresponding positions of the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7 overlap, they are fixed by hollow rivets 5, completing the bonding of the radiation patch 1, the antenna dielectric substrate 6, and the antenna floor 7 to form the antenna body.

[0051] In the same antenna, different working modes have different current and electric field distributions, which will change repeatedly in units of one cycle. As a short-circuit antenna and the floor structure, placing the hollow rivet 5 near the electric field zero point of a certain mode will not affect the resonant frequency of the mode. However, since the current and electric field distributions of different modes are different, the resonant frequencies of other modes will be affected. The position of the hollow rivet 5 is mainly determined by TM 30 The electric field zero point of the mode is determined by the TM 30 Multiple hollow rivets 5 are placed close to the electric field zero point of the mode; if the hollow rivets 5 are placed in the TM 30 Outside the electric field zero point of the mode, the hollow rivet 5 will affect the TM 30 mode, thus losing the ability to tune the two operating modes independently.

[0052] refer to Fig.11 As shown, it is TM 30 Scalar graph of the electric field in one cycle. In one cycle, TM 30 The electric field is constantly changing. The closer the color is to dark blue, the smaller the electric field is. The closer the hollow rivet 5 is to the dark blue, the stronger the electric field is. 30 The smaller the impact of the mode. Fig.11 It can be seen that the positions suitable for placing the hollow rivet 5 include the four positions in this design and the position where the center of the entire antenna radiation patch is parallel to the gain improvement slot 2. Placing the hollow rivet 5 in the other positions will affect the TM 30 The electric field distribution has a great influence, resulting in the inability to tune the two resonant modes independently. Note that the position of the hollow rivet 5 is not strictly determined by the shape of the antenna radiation patch, but after the shape of the radiation patch is determined, by studying its TM 30The electric field distribution is used to determine the position of the hollow rivet 5.

[0053] It is worth noting that if the antenna adopts PCB technology, the hollow rivet 5 can be directly processed by the metallized via in the PCB. If the antenna adopts a metal plate + air medium structure (the felt in the middle is directly replaced by an air layer), the hollow rivet 5 can be replaced by a screw nut.

[0054] In another embodiment, the hollow rivet 5 is made of brass, and its outer diameter is 2.2 mm. There are at least two hollow rivets 5 arranged symmetrically along the center of the radiation patch 1. There are 4 hollow rivets 5, and the ratio of the spacing between any two adjacent hollow rivets 5 parallel to the edge of the radiation patch 1 to the edge length of the radiation patch 1 is 0.66. The antenna dielectric substrate 6 is wool felt, with a relative dielectric constant of 1.2, a loss tangent of 0.03, a thickness of 0.02λ0, and a length and width of 0.78λ0 (the length and width of the dielectric substrate are the antenna size + the microstrip feed line size). The radiation patch 1 is square, and the ratio of the length of the gain improvement slot 2 to the length of the radiation patch 1 is 0.18. Specifically, the width of the gain improvement slot 2 is 2 mm, TM 30 When the current of the mode flows around the gap, the narrow gap can make the surrounding currents on both sides cancel each other in the radiation far field, thereby reducing the TM 30 The side lobes of the mode can be reduced to improve the gain. Generally speaking, there is no particularly strict requirement for the width of this gap. It is determined in advance when optimizing the gap length. Changes within a small range will not have much impact on the results. The length of the microstrip feed line 4 is 14.5mm and the width is 8mm. The length of the impedance matching gap 3 is 10mm and the width is 4mm. After calculating the gap length, the total length of the microstrip feed line 4 is 0.2λ0. Among them, λ0 represents the wavelength of 2.45GHz frequency in vacuum, which is about 122.44mm (the wavelength calculation formula at different operating frequencies is: speed of light ÷ frequency, in meters. Here, the operating frequency is 2.45GHz, so its wavelength in free space is 3×10 8 ÷2.45×10 9 = 0.12244 m = 122.44 mm). It is worth noting that the overall length of the microstrip line can be around 0.25λ0, and its calculation formula is: (the length of the microstrip feed line 4 + the length of the impedance matching gap) ÷ the free space wavelength of the target operating frequency.

[0055] More specifically, in another embodiment, the thickness of the antenna dielectric substrate 6 is 2 mm. The bandwidth of the microstrip patch antenna is affected by the thickness of the dielectric substrate. Increasing the thickness of the dielectric substrate within a certain range can increase the bandwidth of the antenna. This thickness is selected after comprehensively considering that the bandwidth of the antenna in two frequency bands meets the ISM requirements in the 2.45 GHz and 5.8 GHz frequency bands.

[0056] In a preferred embodiment, the surface resistivity of the radiation patch 1 and the antenna floor 7 is less than 0.05Ω / sq, wherein the length and width of the 1-square radiation patch are both 0.42λ0 (the square microstrip patch works in the fundamental mode TM 10 The size of the module is usually λ e / 2, where λ e / 2 is the waveguide wavelength in the dielectric substrate, Where c is the speed of light, f is the operating frequency, ε e is the effective dielectric constant. After taking into account the edge shortening effect, the actual patch length should be Where ΔL is the equivalent radiation gap length, and its calculation formula is: where ε r is the relative dielectric constant of the dielectric substrate, w is the length and width of the patch, and h is the thickness of the dielectric substrate. The working mode of this design is TM 00 TM 30 model, and did not use TM 10 mode, but the design process of ordinary microstrip patch antennas was referred to when designing the antenna size, and then it was optimized based on the simulation results of the gain-enhancing gap.

[0057] Specifically, the ratio of the length of the gain-enhancing slot 2 to the length of the radiation patch 1 is 0.19. This data is the result of simulation optimization. Increasing the length of the slot within a certain range will reduce the TM 30 mode resonant frequency, improve the directional radiation gain, but when the slot length is too long it will lead to TM 30 The frequency of the mode is different from the TM with a lower frequency 12 Mode overlap causes the radiation patterns of the two modes to interfere with each other, weakening the effect of the gap and causing a decrease in gain. Generally speaking, the size of the antenna is fixed, and the frequencies of its various resonant modes are also fixed. Therefore, this data is the simulation optimization result after comprehensively considering the patch size and high gain design, and then the TM is finally determined by adjusting the size of the square patch. 30 The mode can have a good high-gain radiation effect in the 5.8GHz frequency band.

[0058] In another embodiment, the hollow rivet 5 is made of brass, and its outer diameter is 3.5 mm. The number of hollow rivets 5 is at least two and they are symmetrically arranged along the center of the radiation patch 1. There are 4 hollow rivets 5, and the ratio of the spacing between any two adjacent hollow rivets 5 parallel to the edge of the radiation patch 1 to the edge length of the radiation patch 1 is 0.88. The antenna dielectric substrate 6 is wool felt, with a relative dielectric constant of 1.2, a loss tangent of 0.03, a thickness of 0.02λ0, and a length and width of 0.78λ0. The radiation patch 1 is square, and the ratio of the length of the gain-enhancing slot 2 to the length of the radiation patch 1 is 0.20. The length of the microstrip feed line 4 is 18.5 mm and the width is 10 mm. The length of the impedance matching slot 3 is 14 mm and the width is 6 mm. After calculating the slot length, the total length of the microstrip feed line 4 is 0.27λ0 (the preset operating frequency is 2.45 GHz). The size, quantity and position of hollow rivet 5 are the results of simulation optimization. These three data are consistent with TM 00 The more the number of hollow rivets 5 and the larger their size, the greater the TM 00 The higher the resonant frequency of the mode, the lower the resonant frequency of the mode. The position of the hollow rivet 5 is obtained by simulation TM 30 The electric field zero point of the mode is determined when the hollow rivet 5 is placed in the TM 30 When the mode electric field is near zero, it will not affect the TM 30 The resonant frequency of the mode has a great influence. Because the current near the zero point of the electric field is usually the largest, and the hollow rivet 5 can short-circuit the square patch with the ground, and the short-circuit position is usually the location where the current is the largest. 30 In terms of the model, the current near the zero point of the electric field is already very large, and placing the hollow rivet 5 will basically not have much impact, so it will only affect TM 00 mode resonant frequency. And, TM 00 The current of the mode flows toward the position of the hollow rivet 5, so the symmetrical design of the four hollow rivets 5 can also make the current at the gain-enhancing gap flow in a direction parallel to the gap, minimizing the TM 30 mode gain enhancement gap for TM 00 mode, thereby increasing the design freedom and the frequency-independent tunability of the two modes.

[0059] In one embodiment, the radiation patch 1 and the antenna floor 7 are made of conductive cloth. The conductive cloth material is first chemically deposited or physically transferred to the polyester fiber by metal nickel, and then a highly conductive copper layer is plated on the nickel. The copper layer is then electroplated with anti-oxidation and anti-corrosion nickel metal. The combination of copper and nickel provides excellent conductivity and good electromagnetic shielding effect, and the shielding range is 100K-3GHz. The radiation patch 1 and the antenna floor of the antenna are made of conductive cloth, and the dielectric substrate is wool felt, which can effectively increase the wearing comfort and conformal ability of the antenna.

[0060] In one embodiment, the antenna dielectric substrate 6 is wool felt, with a relative dielectric constant of 1.2, a loss tangent of 0.03, a thickness of 0.02λ0, and a length and width of 0.78λ0. The radiation patch 1 is square, and the ratio of the length of the gain-enhancing slot 2 to the length of the radiation patch 1 is 0.19. The length of the microstrip feed line 4 is 16.5mm and the width is 9mm. The width of the microstrip feed line 4 affects its characteristic impedance. In order to match the impedance of the SMA feed connector with an input impedance of 50 ohms, the data is calculated by the microstrip line calculation tool, which is the width of the microstrip feed line 4 when the characteristic impedance is 50 ohms, and then further optimized by simulation. The length of the impedance matching slot 3 is 12mm and the width is 5mm. After calculating the slot length, the total length of the microstrip feed line 4 is 0.23λ0, which is used to feed and adjust the impedance matching of the antenna. The width of the microstrip feed line 4 is to match the impedance with the SMA connector. The length of the microstrip feed line 4 and the size of the impedance matching gap 3 are adjusted to match the impedance of the microstrip feed line 4 with the antenna. The result is the simulation optimization result. If the two impedance matching effects are not good, the antenna performance will deteriorate. For the purpose of this application, the hollow rivet 5 is loaded to excite the TM of the antenna. 00 mode, achieving omnidirectional radiation characteristics that meet the requirements of on-body communication. Gain-enhanced Slot Suppression AntennaTM 30 The side lobes of the mode are reduced to achieve high-gain side-radiation characteristics. The gain-enhancing slot is designed parallel to the TM 00 Mode current position, hollow rivet 5 is designed in TM 30 The electric field zero point of the mode can effectively reduce the design interference problem of the two frequency bands, improve the independent frequency modulation capability of the two frequency bands, and increase the design freedom. Conductive cloth and wool felt are used to improve the wearing comfort and conformal ability of the antenna.

[0061] The antenna adopts the square microstrip patch antenna with microstrip line side feeding, which has the advantage of simple structure. The TM of the antenna is stimulated by loading brass rivets. 00mode, achieving omnidirectional radiation in the 2.45GHz band, with gains in the band (2.4-2.4835GHz) above 1.2dBi and peak gain of 1.5dBi, meeting the requirements of the on-body communication mode. The TM suppression is achieved by loading the gap 30 Mode sidelobes, improve the demand for side-fire gain. The antenna gain in the 5.8GHz band (5.725-5.875GHz) is above 9.5dBi, with a peak gain of 9.9dBi. The gain fluctuation within the band is very small, and the side-fire gain is significantly higher than the existing flexible wearable dual-band dual-mode antenna while ensuring a simple structure, effectively improving the communication quality of the off-body communication mode.

[0062] It is worth mentioning that the feeding scheme can also use SMA probe feeding, that is, no microstrip line side feeding plus gap for impedance matching. By adjusting the position of the probe, the feeding port of the antenna can also be matched to 50Ω. In actual design and processing, the probe in the middle of the SMA connector can be directly welded to the radiator of the antenna, and then the grounding structure of the SMA connector can be welded to the floor. The position of the probe and the entire floor need to be designed with a ring gap according to the SMA connector to avoid short circuit caused by direct connection between the probe and the floor.

[0063] Figure 4 It is a graph showing the reflection coefficient of the antenna changing with frequency. Its -10dB impedance bandwidth covers the two frequency bands of 2.39-2.48GHz and 5.64-5.93Ghz, and can completely cover the ISM bands of 2.45GHz and 5.8Ghz.

[0064] Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 is the normalized radiation pattern of the antenna, and its frequency points and sections are: Figure 5 2.45GHz, phi=0°, theta=0°; Figure 6 2.45GHz, phi=90°, theta=0°; Figure 7 2.45GHz, phi = 0°, theta = 90°; Figure 8 5.8GHz, phi=0°, theta=0°; Fig. 9 The results show that the designed antenna achieves good omnidirectional radiation characteristics at 2.45 GHz and good side-radiation characteristics at 5.8 GHz.

[0065] Fig.10The curve graph of the antenna gain changing with frequency shows that the gain in the 2.45 GHz band is above 1.2 dBi, with a peak gain of 1.5 dBi; the gain in the 5.8 GHz band is above 9.5 dBi, with a peak gain of 9.9 dBi. That is, the designed antenna has obvious side-fire gain enhancement characteristics, and the gain fluctuation is very small within the frequency band.

[0066] In summary, this design has the characteristics of simple structure, easy implementation, good impedance matching between the two frequency bands of 2.45GHz and 5.8GHz, omnidirectional radiation mode and directional radiation mode, and high gain characteristics of the directional radiation mode. Compared with the existing flexible wearable dual-frequency dual-mode antenna design [6-7], the directional radiation gain of this design is significantly higher, and the dual frequencies can be tuned independently, which has great advantages.

[0067] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A dual-frequency dual-mode fabric antenna with enhanced side-fire gain, characterized in that: Said include: Radiating patch, antenna dielectric substrate, and antenna floor; The radiation patch is attached to the upper surface of the antenna dielectric substrate, and the lower surface of the antenna dielectric substrate is attached to the antenna floor; A gain improvement slot is provided on each symmetrical side of the radiation patch, and the other side of the radiation patch extends outward to form a microstrip feed line. Impedance matching slots are provided on both sides of the microstrip feed line and between the radiation patch.

2. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The radiation patch, the antenna dielectric substrate and the antenna floor are attached to each other.

3. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The radiation patch, the antenna dielectric substrate and the antenna floor are all provided with rivet holes; It also includes a hollow rivet, through which the radiation patch, the antenna dielectric substrate, and the antenna floor are connected to realize the TM of the excitation antenna. 00 model.

4. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 3, characterized in that: The hollow rivet is made of brass, and has an outer diameter of 2.2 to 3.5 mm. There are at least two hollow rivets, which are symmetrically arranged along the center of the radiation patch.

5. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 4, characterized in that: There are four hollow rivets, and the ratio of the distance between any two adjacent hollow rivets parallel to the edge of the radiation patch to the edge length of the radiation patch is 0.66-0.

88.

6. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The radiation patch and the antenna floor are made of conductive cloth.

7. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The antenna dielectric substrate is wool felt, with a relative dielectric constant of 1.2, a loss tangent of 0.03, a thickness of 0.02λ0, and a length and a width of 0.78λ0.

8. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The radiation patch is square, and the ratio of the length of the gain improvement slot to the length of the radiation patch is 0.18-0.

20.

9. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The length of the microstrip feed line is 16.5±2 mm and the width is 9±1 mm.

10. The dual-frequency dual-mode fabric antenna with enhanced side-fire gain according to claim 1, characterized in that: The impedance matching gap has a length of 12±2 mm and a width of 5±1 mm. After calculating the gap length, the total length of the microstrip feed line is 0.23λ0.

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