Microstrip antenna and antenna system

Abstract

The application provides a microstrip antenna and an antenna system, wherein the microstrip antenna comprises a dielectric substrate, a ground plate and a microstrip line. The ground plate is arranged on one side surface of the dielectric substrate, and branches and grooves are arranged on the two side edges of the ground plate. The branches and grooves are periodically arranged in the length direction of the ground plate, so that the microstrip antenna is formed into a horizontal polarization microstrip antenna or a vertical polarization microstrip antenna. The microstrip line is arranged on the other side surface of the dielectric substrate. The microstrip antenna provided by the application can greatly enhance the radiation capacity of the microstrip antenna by periodically arranging the branches and grooves on the ground plate. The horizontal polarization or the vertical polarization of the microstrip antenna can be realized by changing the design shape, size and arrangement of the branches and grooves, so that the characteristics of near distance coverage, high capacity and anti-interference of electromagnetic waves can be realized, and the electromagnetic waves can be uniformly and comprehensively covered in a narrow and long space.

Description

Technical Field

[0001] This application relates to the field of communication antenna technology, and in particular to a microstrip antenna and antenna system. Background Technology

[0002] Mobile communication has entered the fifth generation (5G) era, basically achieving wide-area coverage of wireless signals in geographic space. However, due to the diversity and complexity of service scenarios, coupled with the imperfect antenna directionality, weak coverage areas, blind spots, or insufficient capacity still commonly exist, such as various tunnels, alleyways, aircraft cabins, and elevator shafts. In these narrow and enclosed special service scenarios, conventional antennas are generally used as the coverage solution. However, the electromagnetic waves radiated by conventional antennas suffer from severe signal attenuation, path obstruction, absorption, interference, and reflection as they propagate through space to distant locations. Summary of the Invention

[0003] The purpose of this application is to provide a dual-polarized antenna to solve the problem of severe signal attenuation of electromagnetic waves radiated by existing conventional antennas during long-distance propagation in special business scenarios with narrow and enclosed spaces.

[0004] A first aspect of this application provides a microstrip antenna, comprising a dielectric substrate, a ground plane, and a microstrip line. The ground plane is disposed on one surface of the dielectric substrate, and stubs and grooves are provided on both sides of the ground plane. The stubs and grooves are periodically arranged along the length of the ground plane, thereby forming the microstrip antenna as a horizontally polarized microstrip antenna or a vertically polarized microstrip antenna. The microstrip line is disposed on the other surface of the dielectric substrate.

[0005] The microstrip antenna provided in this application can greatly enhance its radiation capability by periodically setting stubs and grooves on the floor. Furthermore, by changing the design shape, size, and arrangement of the stubs and grooves, the microstrip antenna can be horizontally or vertically polarized, thereby achieving the characteristics of short-range electromagnetic wave coverage, high capacity, and anti-interference, enabling electromagnetic waves to uniformly and comprehensively cover a narrow space.

[0006] In one possible implementation, the grooves are symmetrically formed on both sides of the floor in the width direction. The branches include a first branch and a second branch. The first branch is disposed in a portion of the groove and is alternately arranged on both sides of the floor in the width direction. The second branch is disposed between two adjacent grooves and is connected to the edge of the floor. The second branch is also alternately arranged on both sides of the floor in the width direction. This enhances the radiation performance of the microstrip antenna and enables horizontal polarization of the microstrip antenna.

[0007] In one possible implementation, one end of the first branch is connected to the side of the groove near the centerline of the floor in the length direction, and the other end of the first branch extends in a straight line in the width direction of the floor to the edge of the dielectric substrate.

[0008] In one possible implementation, the second branch includes a first segment, a second segment, and a third segment, the first segment and the third segment being perpendicularly connected to the second segment, the second segment being parallel to the edges of the floor on both sides in the width direction, and the ends of the first segment and the third segment away from the second segment being connected to the edge of the floor.

[0009] In one possible implementation, the length of the first stub is (0.25–0.35) × λc, where λc is the waveguide wavelength at the center frequency of the microstrip line. This ensures that the antenna has good radiation performance.

[0010] In one possible implementation, the distance between two adjacent grooves, the distance between two adjacent first stubs, or the distance between two adjacent second stubs is equal along the length of the floor. By distributing the grooves, first stubs, and second stubs at equal intervals along the length of the floor, the uniformity of the antenna's radiation performance can be ensured.

[0011] In one possible implementation, along the length of the floor, the distance between two adjacent grooves, the distance between two adjacent first stubs, or the distance between two adjacent second stubs is (0.35–0.65) × λc, where λc is the waveguide wavelength at the center frequency of the microstrip line. Ensuring that the distances between two adjacent grooves, the distances between two adjacent first stubs, or the distances between two adjacent second stubs satisfy the aforementioned range guarantees balanced radiation performance throughout the antenna.

[0012] In one possible implementation, the distance from the side of the groove closest to the centerline of the floor along its length to the centerline is at least 0.20 × λc, where λc is the guided wavelength of the microstrip line center frequency. This ensures that the antenna has good radiation performance.

[0013] In one possible implementation, the grooves are symmetrically formed on both sides of the floor in the width direction; the grooves include a first groove and a second groove, and in the length direction of the floor, the first groove is located near the end of the floor, and the second groove is located on the side of the first groove away from the end of the floor; the stubs include a third stub and a fourth stub, the third stub being located between the first groove and the second groove, and between two adjacent second grooves, and the third stub being connected to the edge of the floor; the fourth stub is located in the second groove; the third stub and the fourth stub are symmetrically arranged on both sides in the width direction of the floor. Thus, a microstrip antenna having the aforementioned first groove, second groove, third stub, and fourth stub can achieve vertical polarization.

[0014] In one possible implementation, the width of the second slot is greater than the width of the first slot, thereby enabling the fourth stub to be designed to a larger size and placed in the second slot, thus giving the antenna good radiation performance.

[0015] In one possible implementation, the third branch includes a fourth segment, a fifth segment, and a sixth segment, the fourth segment and the sixth segment being perpendicularly connected to the fifth segment, the fifth segment being parallel to the edges of the floor in the width direction, and the ends of the fourth segment and the sixth segment away from the fifth segment being connected to the edge of the floor.

[0016] In one possible implementation, the fourth branch includes a seventh segment, an eighth segment, a ninth segment, a tenth segment, and an eleventh segment. One end of the seventh segment and the eighth segment are respectively perpendicularly connected to both ends of the ninth segment, and the other ends of the seventh segment and the eighth segment are respectively perpendicularly connected to the tenth segment and the eleventh segment. The tenth segment and the eleventh segment are connected to the second groove on one side near the center line of the floor in the length direction. The ninth segment is parallel to the edge of the floor and is flush with the position of the fifth segment.

[0017] In one possible implementation, the distance from the side of the first and second slots closest to the centerline of the floor along the length direction to the centerline is at least 0.20 × λc, where λc is the guided wavelength of the microstrip line center frequency. This ensures that the antenna has good radiation performance.

[0018] In one possible implementation, the distances between two adjacent second slots, two adjacent third stubs, or two adjacent fourth stubs are equal along the length of the floor. By distributing the second slots, third stubs, and fourth stubs at equal intervals along the length of the floor, the uniformity of the antenna's radiation performance can be ensured throughout the antenna.

[0019] In one possible implementation, the distance between two adjacent second slots, two adjacent third stubs, or two adjacent fourth stubs along the length of the floor is (0.35–0.65) × λc, where λc is the guided wavelength of the microstrip line center frequency. This ensures balanced radiation performance throughout the antenna.

[0020] In one possible implementation, the microstrip line includes a main feed line and an impedance transformation section. The main feed line is located above or below the midline of the ground plane, and the impedance transformation section is symmetrically connected to both ends of the main feed line to match a set input impedance of 50 ohms.

[0021] In one possible implementation, the impedance transformation section includes at least a first transformation section and a second transformation section of equal length but unequal width. The first transformation section is symmetrically connected to the left and right ends of the main feeder along its length, and the second transformation section is symmetrically connected to the outer ends of the first transformation section at both ends of the main feeder. This achieves the impedance transformation function.

[0022] In one possible implementation, the lengths of the first transformation segment and the second transformation segment are at least 0.25 × λc, where λc is the waveguide wavelength of the microstrip line center frequency.

[0023] In one possible implementation, the dielectric substrate is a flexible dielectric substrate. This flexible dielectric substrate enables the microstrip antenna to be flexibly rolled up, and during recycling, it can be wound around a cylindrical structure such as a cylindrical ingot, facilitating recycling, carrying, and storage.

[0024] In one possible implementation, the dielectric substrate is made of polytetrafluoroethylene (PTFE), polyimide (PI), or polycarbonate (PC). Using such materials allows the dielectric substrate to have good flexibility, facilitating the bending of the entire microstrip antenna and simplifying recycling and management; it also enables the dielectric substrate to have low loss and low dielectric constant, thereby reducing transmission loss and increasing the coverage distance along the length of the microstrip antenna.

[0025] In one possible implementation, the thickness of the dielectric substrate is less than or equal to 2 mm. Using a dielectric substrate of this thickness allows for both flexibility and low loss and low dielectric constant, thereby reducing transmission loss and increasing the coverage distance along the length of the radiation line.

[0026] In one possible implementation, a copper plating layer is disposed on the dielectric substrate, and the thickness of the copper plating layer is at least 35 μm. This ensures that the dielectric substrate has low loss and long-distance coverage characteristics.

[0027] The second aspect of this application also provides an antenna system comprising at least two microstrip antennas provided in the first aspect of this application, and comprising at least two of the microstrip antennas being combinations of horizontally polarized microstrip antennas, or at least two of the microstrip antennas being combinations of vertically polarized microstrip antennas, or at least two of the microstrip antennas being combinations of horizontally polarized microstrip antennas and vertically polarized microstrip antennas.

[0028] The antenna system provided in this application employs a microstrip antenna comprising a dielectric substrate, a ground plane, and a microstrip line. By setting grooves and stubs on the ground plane, the radiation performance of the microstrip line is enhanced. Furthermore, by combining at least two microstrip antennas, the antenna system can achieve good radiation performance in narrow areas such as tunnels and alleyways, thereby increasing antenna capacity and achieving uniform coverage.

[0029] In one possible implementation, the antenna system includes 2 n-1 The horizontally polarized microstrip antenna and 2 n-1 The vertically polarized microstrip antennas are defined as follows, where n = 1, 2, 3…k, and k is a positive integer. The horizontally polarized microstrip antennas and the vertically polarized microstrip antennas are of equal length and are arranged side-by-side in parallel. By combining and deploying multiple H / V polarized microstrip antennas, polarization diversity and spatial diversity MIMO can be achieved simultaneously, significantly improving capacity and increasing radiation capability by at least 20dB.

[0030] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0031] Figure 1 This is a top view of an H-polarized microstrip antenna.

[0032] Figure 2 for Figure 1 Sectional view along the AA direction;

[0033] Figure 3 for Figure 1 A magnified view of a portion of the middle left area;

[0034] Figure 4 for Figure 1 A magnified view of a portion of the right-middle area;

[0035] Figure 5 for Figure 1 A magnified view of a portion of the central area;

[0036] Figure 6 The far-field radiation pattern of the H-polarized microstrip antenna;

[0037] Figure 7The differential loss |S21| curve of the H-polarized microstrip antenna;

[0038] Figure 8 The VSWR curve of an H-polarized microstrip antenna;

[0039] Figure 9 The Smith chart for an H-polarized microstrip antenna;

[0040] Figure 10 This is a top view of a V-polarized microstrip antenna;

[0041] Figure 11 for Figure 10 A magnified view of a portion of the middle left area;

[0042] Figure 12 for Figure 10 A magnified view of a portion of the right-middle area;

[0043] Figure 13 for Figure 10 A magnified view of a portion of the central area;

[0044] Figure 14 The far-field radiation pattern of the V-polarized microstrip antenna;

[0045] Figure 15 The difference loss |S21| curve for a V-polarized microstrip antenna;

[0046] Figure 16 The VSWR curve of a V-polarized microstrip antenna;

[0047] Figure 17 Smith chart for V-polarized microstrip antenna;

[0048] Figure 18 This is a state diagram of the combination of two H-polarized microstrip antennas;

[0049] Figure 19 This is a state diagram of the combination of two V-polarized microstrip antennas;

[0050] Figure 20 The state diagram is shown for the combination of an H-polarized microstrip antenna and a V-polarized microstrip antenna.

[0051] Figure 21 This is a state diagram of two H-polarized microstrip antennas connected in series.

[0052] Figure 22 The state diagram is shown after two V-polarized microstrip antennas are connected in series.

[0053] Figure 23 A state diagram of an H-polarized microstrip antenna wound on a cylindrical ingot;

[0054] Figure 24 This is a state diagram of a V-polarized microstrip antenna wound on a cylindrical ingot.

[0055] Figure label:

[0056] 1-Dielectric substrate;

[0057] 2-Floor;

[0058] 21-groove;

[0059] 211-First slot;

[0060] 212 - Second slot;

[0061] 3-Microstrip line;

[0062] 31-Main feeder;

[0063] 32-Impedance transformation section;

[0064] 321 - First Transformation Segment;

[0065] 322 - Second Transformation Segment;

[0066] 4-Spurs;

[0067] 41 - First branch;

[0068] 42 - Second branch;

[0069] 421 - First paragraph;

[0070] 422 - Second paragraph;

[0071] 423 - Third paragraph;

[0072] 43 - Third branch;

[0073] 431 - Fourth paragraph;

[0074] 432 - Fifth paragraph;

[0075] 433 - Paragraph 6;

[0076] 44 - Fourth branch;

[0077] 441 - Paragraph 7;

[0078] 442 - Paragraph 8;

[0079] 443 - Ninth paragraph;

[0080] 444 - Paragraph 10;

[0081] 445 - Paragraph 11;

[0082] A - Unit 1;

[0083] B-Unit Two;

[0084] 100-Horizontal Polarized Microstrip Antenna;

[0085] 200-Vertical Polarized Microstrip Antenna;

[0086] 300-RF connector;

[0087] 400-RF cable;

[0088] 500 - Absorbed load;

[0089] 600-cylindrical ingot;

[0090] d1 - Distance;

[0091] d2 - distance;

[0092] O-matching point.

[0093] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0094] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0095] In the description of this application, unless otherwise expressly specified and limited, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected," "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0096] In the description of this specification, it should be understood that the directional terms such as "upper" and "lower" used in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should also be understood that when it is mentioned that an element is connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0097] Mobile communication has basically achieved wide-area coverage of wireless signals in geographic space. Currently, conventional antennas are generally used as the coverage solution. However, in scenarios such as various tunnels, alleys, cabins, and elevator shafts, conventional antennas still suffer from weak signal coverage and insufficient capacity. Especially in narrow areas such as tunnels, the electromagnetic waves radiated by conventional antennas experience severe signal attenuation, path obstruction, absorption, interference, and reflection as they propagate through space to distant locations.

[0098] Therefore, this application provides a microstrip antenna, which includes a dielectric substrate 1, a ground plane 2, and a microstrip line 3. The ground plane 2 is disposed on one surface of the dielectric substrate 1, and stubs 4 and grooves 21 are disposed on both sides of the ground plane 2. The stubs 4 and grooves 21 are periodically arranged along the length of the ground plane 2, so that the microstrip antenna is formed as a horizontally polarized (H-polarized) microstrip antenna or a vertically polarized (V-polarized) microstrip antenna. The microstrip line is disposed on the other surface of the dielectric substrate 1. That is, as shown... Figure 2 As shown, the microstrip line 3 and the ground plane 2 are located on both sides of the dielectric substrate 1 in the thickness direction.

[0099] While the individual microstrip line 3 has relatively weak radiation capability, in this application, by periodically setting stubs and grooves 21 on the floor 2, the radiation capability of the microstrip antenna can be greatly enhanced. Furthermore, by changing the design shape, size, and arrangement of the stubs and grooves 21, horizontal or vertical polarization of the microstrip antenna can be achieved. The antenna system formed by combining the horizontally polarized microstrip antenna 100 and the vertically polarized microstrip antenna 200 can achieve short-range electromagnetic wave coverage, high capacity, and anti-interference characteristics. Simultaneously, the antenna system composed of the horizontally polarized microstrip antenna 100 and the vertically polarized microstrip antenna 200 can have a relatively long length, ranging from tens to hundreds of meters, allowing it to be deployed throughout a narrow space, enabling uniform and comprehensive electromagnetic wave coverage. This antenna system also possesses strong anti-interference capabilities, especially in situations with large obstacles, such as high-speed trains or subway trains passing through tunnels. Therefore, the microstrip antenna provided in this application replaces the existing conventional antenna and solves the problems of severe signal attenuation, path blockage, absorption, interference, and reflection that exist in conventional antennas during the propagation of radiated waves in space.

[0100] Furthermore, existing technologies also employ leaky cables as antenna coverage solutions. Leaky cables are typically formed by creating multiple slots in a conventional antenna to improve near-field coverage. However, leaky cables also have significant drawbacks: they can only achieve vertical polarization and cannot achieve other polarization methods, such as horizontal polarization. This prevents polarization diversity and limits the antenna system's capacity. Additionally, due to the small diameter of the leaky cable, the size of its slots is often much smaller than the operating wavelength, inevitably resulting in weak radiation capability. Increasing the leaky cable diameter to increase the slot size could enhance radiation capability, but this would introduce higher-order modes (TE and TM) in the high-frequency band, in addition to the dominant TEM mode, leading to a sharp increase in reflection coefficient and significantly increased loss, thus narrowing the leaky cable's operating bandwidth. Therefore, relying on increasing the leaky cable diameter to achieve leaky cable polarized MIMO functionality is theoretically not feasible.

[0101] In engineering practice, several leaky cables are typically placed parallel to each other at a certain distance. Because all leaky cables have the same polarization, strong mutual coupling exists between closely spaced leaky cables, resulting in poor MIMO performance and significantly limiting capacity expansion capabilities. Furthermore, conventional leaky cables do not support higher frequency bands such as 3.5 GHz and 4.9 GHz, leading to significant losses and generally limiting their operation to frequencies below 3.5 GHz. In addition, conventional leaky cables are complex to install; they cannot be laid directly on the ground and usually need to be fixed to wall brackets. Fixing these brackets requires drilling several holes in the wall, which is time-consuming and labor-intensive. Additionally, during installation, the slots on the leaky cable need to face outwards, requiring frequent rotation of the cable to adjust the slot orientation, which also reduces installation efficiency.

[0102] Therefore, such as Figure 1 and Figure 2 As shown in the embodiment of this application, the microstrip antenna includes, from bottom to top, a ground plane 2, a dielectric substrate 1, and a microstrip line 3. By periodically setting stubs and grooves 21 on the ground plane 2, the microstrip antenna can achieve horizontal or vertical polarization, possessing strong radiation capability and enabling polarized MIMO functionality, thus enhancing the antenna system capacity. It is suitable for narrow areas such as tunnels and alleys, allowing electromagnetic waves to uniformly cover all parts of the narrow area. Furthermore, during installation, the ground plane 2 is simply fixed to the surface of the object, with the microstrip line 3 facing outwards, eliminating the need for frequent adjustments to the microstrip antenna and making installation convenient.

[0103] In addition, in large venues such as stadiums, music venues, and exhibition halls, antenna systems need to be temporarily deployed when used in these locations, and then recycled after use. However, existing conventional antennas and leaky cables are relatively long and made of rigid materials, making them difficult to recycle and manage.

[0104] Therefore, in this embodiment, as Figure 23 and Figure 24 As shown, the dielectric substrate 1 is a flexible dielectric substrate manufactured using a printed circuit process, which enables the microstrip antenna to be flexible and coiled. During recycling, it can be wound around a cylindrical structure such as a cylindrical ingot 600, facilitating recycling, carrying, and storage. Compared to conventional antennas and conventional leaky cables, this microstrip antenna has significant advantages in coverage, capacity, cost, weight, installability, and recyclability.

[0105] The dielectric substrate 1 is made of materials including, but not limited to, polytetrafluoroethylene (PTFE), polyimide (PI), or polycarbonate (PC). Using these materials allows the dielectric substrate 1 to have good flexibility, facilitating the bending of the entire microstrip antenna and making it easy to recycle and manage. It also enables the dielectric substrate 1 to have low loss and low dielectric constant, thereby reducing transmission loss and increasing the coverage distance of the microstrip antenna along its length.

[0106] Specifically, the thickness of the dielectric substrate 1 is less than or equal to 2 mm. Using a dielectric substrate 1 of this thickness allows it to maintain flexibility while achieving low loss and low dielectric constant, thereby reducing transmission loss and increasing the coverage distance along the length of the radiation line.

[0107] Furthermore, a copper plating layer can be disposed on the dielectric substrate 1. A thick copper plating layer can ensure that the dielectric substrate 1 has low loss and long-distance coverage characteristics. However, the thickness of the copper plating layer cannot be too thick, otherwise it will also increase the coverage margin. In this embodiment, the thickness of the copper plating layer is at least 35 μm.

[0108] As a specific implementation method, Figure 1 This is a top view of an H-polarized microstrip antenna. Figure 3 for Figure 1 A magnified view of a portion of the middle left area. Figure 4 for Figure 1 A magnified view of a portion of the right-middle area. Figure 5 for Figure 1 A magnified view of the central region shows that the dielectric substrate 1 can be made of a transparent material, and the ground plane 2 structure on the other side of the dielectric substrate 1 can also be seen from the side with the microstrip line 3. Figure 1 , Figures 2 to 5 As shown, the grooves 21 are symmetrically formed on both sides of the floor 2 in the width direction. The branches include a first branch 41 and a second branch 42. The first branch 41 is disposed in part of the groove 21, and the first branch 41 is alternately arranged on both sides of the floor 2 in the width direction. That is, the first branch 41 on one side of the floor 2 in the width direction and the first branch 41 on the other side of the floor 2 in the width direction intersect each other in the width direction of the floor 2.

[0109] The second branch 42 is disposed between two adjacent grooves 21 and is connected to the edge of the floor 2. The second branch 42 is arranged alternately on both sides of the floor 2 in the width direction. That is, the second branch 42 on one side of the floor 2 in the width direction and the second branch 42 on the other side of the floor 2 in the width direction intersect each other in the width direction of the floor 2.

[0110] Among them, such as Figures 3 to 5 As shown, in the width direction of the floor 2, a second branch 42 is disposed on the outside of the floor 2 and can connect to the edge of the floor 2. The second branch 42 is disposed between two adjacent grooves 21, and one of the two adjacent grooves 21 has a first branch 41, while the area between the two grooves 21 adjacent to the second branch 42 does not have a second branch 42. Thus, two grooves 21, two first branches 41, and two second branches 42 can constitute a first unit A, and multiple such first units are evenly arranged in the length direction of the floor 2.

[0111] In this embodiment, as Figure 1 As shown, the microstrip antenna with the aforementioned groove 21, first stub 41, and second stub 42 can achieve horizontal polarization, thus forming a horizontally polarized microstrip antenna 100. Specifically, the first stub 41 can make the direction of the current consistent with the width direction of the ground plane 2, while the second stub 42 can cancel the current in the opposite direction in the length direction of the ground plane 2, thereby making the current flow only in the width direction of the ground plane 2, thereby achieving horizontal polarization of the microstrip antenna.

[0112] Specifically, such as Figure 1 , Figures 3 to 5As shown, one end of the first branch 41 is connected to the side of the groove 21 near the centerline of the ground plane 2 in the length direction, and the other end of the first branch 41 extends in a straight line in the width direction of the ground plane 2 to the edge of the dielectric substrate 1. The first branch 41 is generally in the shape of a straight line and is located in the middle of the groove 21. Since the first branches 41 are all parallel to the width direction of the ground plane 2, the current direction in the first branch 41 can be made consistent with the width direction of the ground plane 2. At the same time, since the first branches 41 on both sides of the ground plane 2 are staggered in the length direction of the ground plane 2, the currents in the first branches 41 on both sides of the ground plane 2 can be prevented from canceling each other out, thus ensuring the radiation performance of the antenna in the width direction of the ground plane 2. Meanwhile, the second stubs 42 are also staggered along the length of the floor 2, which can avoid canceling the current in the width direction. At the same time, the second stubs 42 can also make the direction of some current parallel to the length of the floor 2. The current direction of the second stubs 42 on one side edge of the floor 2 is opposite to the current direction of the second stubs 42 on the other side edge of the floor 2, so that the current in the length of the floor 2 can be canceled, so that the microstrip antenna only has current in the width direction, thereby realizing the H polarization of the microstrip antenna and enhancing the radiation performance of the antenna in the horizontal direction.

[0113] Specifically, such as Figure 3 As shown, the second branch 42 includes a first segment 421, a second segment 422, and a third segment 423. The first segment 421 and the third segment 423 are perpendicularly connected to the second segment 422. The second segment 422 is parallel to the edges of the floor 2 on both sides in the width direction. The ends of the first segment 421 and the third segment 423 away from the second segment 422 are connected to the edge of the floor 2. The overall shape of the second branch 42, which is composed of the first segment 421, the second segment 422, and the third segment 423, is "U"-shaped, and the second segment 422 maintains a distance from the edge of the dielectric substrate 1.

[0114] As a specific implementation, the length of the first stub 41 is (0.25~0.35)×λc, where λc is the waveguide wavelength of the center frequency of the microstrip line 3. Within this length range, the first stub 41 can ensure that the antenna has good radiation performance.

[0115] As a specific implementation, the distance between two adjacent grooves 21, the distance between two adjacent first branches 41, or the distance between two adjacent second branches 42 is equal along the length of the floor 2. Specifically, the grooves 21, the first branches 41, and the second branches 42 are distributed at equal intervals along the length of the floor 2 to ensure balanced radiation performance of the antenna at all points.

[0116] In the longitudinal direction of the floor 2, the distance between two adjacent grooves 21, the distance between two adjacent first branches 41, or the distance between two adjacent second branches 42 is (0.35~0.65)×λc, where λc is the wavelength of the guided wave at the center frequency of the microstrip line 3. Ensuring that the distances between two adjacent grooves 21, two adjacent first branches 41, or two adjacent second branches 42 satisfy the above-mentioned distance range guarantees the balanced radiation performance of the antenna at all points.

[0117] As a specific implementation method, such as Figure 3 As shown, the distance d1 from the side of the groove 21 closest to the centerline of the ground plane 2 in the length direction to the centerline is at least 0.20 × λc, where λc is the wavelength of the guided wave at the center frequency of the microstrip line 3. The ground plane 2 has a symmetrical structure in the width direction, with its center of symmetry being the centerline of the ground plane 2 in the length direction. The groove 21 is formed at the edge of the ground plane 2, extending towards the aforementioned centerline and maintaining a certain distance from it, which is not less than 0.20 × λc. This ensures that the antenna has good standing wave and radiation performance.

[0118] It should be noted that for the microstrip antenna including the groove 21, the first stub 41, and the second stub 42, in the overall structure, along the length of the ground plane 2, one of two adjacent grooves 21 has a first stub 41, while the other groove 21 does not have a first stub 41. There is only one second stub 42 between two adjacent first stubs 41. Since the ground plane 2 has grooves 21, first stubs 41, and second stubs 42 on both sides along its width, thus, as... Figure 5 As shown, the four grooves 21, two first branches 41 and two second branches 42 on the floor 2 can form a first unit A. That is to say, the arrangement of multiple first units A realizes the periodic arrangement of grooves 21, first branches 41 and second branches 42.

[0119] like Figure 1 As shown, in this embodiment, H-polarization can be achieved for the microstrip antenna including the groove 21, the first stub 41, and the second stub 42. Figure 6 In the far-field radiation pattern of the H-polarized microstrip antenna shown, the solid line represents the horizontal plane radiation pattern (width direction of floor 2), and the dashed line represents the vertical plane radiation pattern (length direction of floor 2). The smooth lines represent the dominant polarization components, and the dotted lines represent the cross-polarization components. Specifically, the solid lines with dots (shown as black square dots in the figure) represent the Phi component of the horizontal plane, and the dashed lines with dots represent the Theta component of the vertical plane. The Phi component of the horizontal plane is smaller than the Theta component, and the Theta component of the vertical plane is smaller than the Phi component. This means that the dominant polarization on the horizontal plane is the Theta component, indicating that the microstrip antenna is horizontally H-polarized.

[0120] Figure 7 This is a graph showing the differential loss |S21| of an H-polarized microstrip antenna. The horizontal axis represents frequency in GHz, and the vertical axis represents the antenna differential loss S21 in dB. Figure 7 It can be seen that at a frequency of 2.48 GHz, the antenna's differential loss is -0.6749. Therefore, the differential loss of this microstrip antenna is very small, which reduces transmission loss and allows the antenna to cover a long distance along its length.

[0121] Figure 8 This is a VSWR curve for an H-polarized microstrip antenna. The horizontal axis represents frequency in GHz, and the vertical axis represents VSWR. The solid line represents the VSWR at the left port of the antenna, and the dashed line represents the VSWR at the right port. Figure 8 It can be seen that in the 2.20–2.80 GHz frequency band, the maximum VSWR of the left and right ports of the antenna does not exceed 1.1140. This allows the antenna to achieve good impedance matching, has a large bandwidth, reduces reflection loss, and improves the antenna's radiation performance.

[0122] Figure 9 This is the Smith chart of an H-polarized microstrip antenna. (From...) Figure 9 It can be seen that the antenna impedance is close to the matching point O on the Smith chart. Figure 9 The black dot at the center of the circular diagram shown can improve the antenna impedance mismatch problem and maximize transmission efficiency.

[0123] In another implementation, such as Figures 10 to 13 As shown, the microstrip antenna in this embodiment can achieve vertical polarization. Specifically, the grooves 21 are symmetrically formed on both sides of the ground plane 2 in the width direction. It can be understood that the ground plane 2 has a symmetrical structure in the width direction, and its center of symmetry is the centerline of the ground plane 2 in the length direction.

[0124] Among them, such as Figures 10 to 13 As shown, the groove 21 includes a first groove 211 and a second groove 212. Along the length of the floor 2, the first groove 211 is located near the end of the floor 2, and the second groove 212 is located on the side of the first groove 211 away from the end of the floor 2. In this embodiment, on any side edge along the width of the floor 2, there are two first grooves 211, each located near both ends of the floor 2, and multiple second grooves 212 are located in the area between the two first grooves 211.

[0125] In this embodiment, as Figures 10 to 13As shown, branch 4 includes a third branch 43 and a fourth branch 44. The third branch 43 is disposed between the first groove 211 and the second groove 212, that is, between the first groove 211 near the end of the floor 2 and the adjacent second groove 212, and between two adjacent second grooves 212, and the third branch 43 is connected to the edge of the floor 2. The fourth branch 44 is disposed in the second groove 212. The third branch 43 and the fourth branch 44 are symmetrically arranged on both sides in the width direction of the floor 2.

[0126] The vertically polarized microstrip antenna 200 can be an antenna with a symmetrical structure in both the width and length directions of the ground plane 2. In the width direction of the ground plane 2, the third stub 43 is disposed outside the ground plane 2 and can be connected to the edge of the ground plane 2. The fourth stub 44 is partially located in the second slot 212 and partially located outside the ground plane 2. Thus, as... Figure 13 As shown, the third branch 43 and the fourth branch 44 are arranged alternately, that is, two third branches 43, two fourth branches 44 and two second grooves 212 constitute the second unit B, and multiple second units B are evenly arranged in the length direction of the floor 2.

[0127] In this embodiment, as Figure 10 As shown, the microstrip antenna with the aforementioned groove 21, third stub 43, and fourth stub 44 can achieve vertical polarization, thus forming a vertically polarized microstrip antenna 200. Specifically, the third stub 43 and the fourth stub 44 are symmetrically distributed in the width direction of the ground plane 2, thereby canceling out the current in the width direction and allowing the current to propagate only in the length direction of the ground plane 2. This achieves V-polarization of the microstrip antenna and enhances the antenna's radiation performance in the vertical direction.

[0128] The width of the second slot 212 is greater than the width of the first slot 211, which gives the fourth stub 44 a larger size and allows it to be placed in the second slot 212, thus giving the antenna good radiation performance.

[0129] Specifically, such as Figure 11 As shown, the third branch 43 includes a fourth segment 431, a fifth segment 432, and a sixth segment 433. The fourth segment 431 and the sixth segment 433 are perpendicularly connected to the fifth segment 432. The fifth segment 432 is parallel to the edges of the floor 2 on both sides in the width direction. The ends of the fourth segment 431 and the sixth segment 433 away from the fifth segment 432 are connected to the edge of the floor 2. The third branch 43 is generally U-shaped, and the fifth segment 432 maintains a distance from the edge of the dielectric substrate 1.

[0130] In addition, such as Figure 11As shown, the fourth stub 44 includes a seventh segment 441, an eighth segment 442, a ninth segment 443, a tenth segment 444, and an eleventh segment 445. One end of the seventh segment 441 and the eighth segment 442 are vertically connected to both ends of the ninth segment 443, and the other ends of the seventh segment 441 and the eighth segment 442 are vertically connected to the tenth segment 444 and the eleventh segment 445, respectively. The tenth segment 444 and the eleventh segment 445 are connected to one side of the second slot 212 near the centerline of the floor 2 in the length direction. The ninth segment 443 is parallel to the edge of the floor 2 and is flush with the fifth segment 432. The fourth stub 44 is C-shaped overall. The third stub 43 and the fourth stub 44 enable the vertically polarized microstrip antenna 200 to have good radiation performance.

[0131] As a specific implementation method, such as Figure 11 As shown, the distance d2 from the side of the centerline of the floor 2 on the first slot 211 and the second slot 212 near the centerline in the length direction to the centerline is at least 0.20×λc, where λc is the waveguide wavelength of the center frequency of the microstrip line 3.

[0132] The floor 2 has a symmetrical structure in the width direction, and its center of symmetry is the center line of the floor 2 in the length direction. The first slot 211 and the second slot 212 are both opened at the edge of the floor 2, and both the first slot 211 and the second slot 212 extend in the direction of the aforementioned center line and maintain a certain distance from the center line. This distance is not less than 0.20×λc, which can ensure that the antenna has good radiation performance.

[0133] As a specific implementation, the distance between two adjacent second slots 212, the distance between two adjacent third branches 43, or the distance between two adjacent fourth branches 44 are equal along the length of the floor 2. Specifically, the second slots 212, third branches 43, and fourth branches 44 are evenly spaced along the length of the floor 2 to ensure balanced radiation performance of the antenna at all points.

[0134] Specifically, along the length of the floor 2, the distance between two adjacent second slots 212, the distance between two adjacent third branches 43, or the distance between two adjacent fourth branches 44 is (0.35~0.65)×λc, where λc is the guided wavelength of the center frequency of the microstrip line 3. Ensuring that the distances between two adjacent second slots 212, two adjacent third branches 43, or two adjacent fourth branches 44 satisfy the above distance range guarantees the balanced radiation performance of the antenna at all points.

[0135] like Figure 10 As shown, in this embodiment, V-polarization can be achieved for the microstrip antenna including the first slot 211, the second slot 212, the third stub 43, and the fourth stub 44. Figure 14 In the far-field radiation pattern of the V-polarized microstrip antenna shown, the solid line represents the horizontal plane radiation pattern (width direction of floor 2), and the dashed line represents the vertical plane radiation pattern (length direction of floor 2). The smooth lines represent the dominant polarization components, and the dotted lines represent the cross-polarization components. Specifically, the solid lines with dots (shown as black squares in the diagram) represent the Theta component of the horizontal plane, and the dashed lines with dots represent the Phi component of the vertical plane. The Theta component of the horizontal plane is smaller than the Phi component, and the Phi component of the vertical plane is smaller than the Theta component. This means that the dominant polarization in the vertical plane is the Theta component, indicating that the microstrip antenna is horizontally V-polarized.

[0136] Figure 15 This is a graph showing the differential loss |S21| of a V-polarized microstrip antenna. The horizontal axis represents frequency in GHz, and the vertical axis represents the antenna differential loss S21 in dB. Figure 15 It can be seen that at a frequency of 2.50 GHz, the antenna's differential loss is -0.6374. Therefore, the differential loss of this microstrip antenna is very small, which reduces transmission loss and allows the antenna to cover a long distance along its length.

[0137] Figure 16 This is a VSWR curve for a V-polarized microstrip antenna. The horizontal axis represents frequency in GHz, and the vertical axis represents VSWR. The solid line represents the VSWR at the left port of the antenna, and the dashed line represents the VSWR at the right port. This V-polarized microstrip antenna has a symmetrical structure; the VSWR values ​​at the left and right ports are quite consistent, and the curves almost overlap. Figure 16 It can be seen that in the 2.20–2.80 GHz frequency band, the maximum VSWR of the left and right ports of the antenna does not exceed 1.1152. This allows the antenna to achieve good impedance matching, has a large bandwidth, reduces reflection loss, and improves the antenna's radiation performance.

[0138] Figure 17 This is the Smith chart of a V-polarized microstrip antenna. Figure 17 It can be seen that the antenna impedance is close to the matching point O on the Smith chart. Figure 17 The black dot at the center of the circular diagram shown can improve the antenna impedance mismatch problem and maximize transmission efficiency.

[0139] As a specific implementation method, such as Figure 1 As shown, the microstrip line 3 includes a main feed line 31 and an impedance transformation section 32. The main feed line 31 is disposed on the ground plane 2, and the impedance transformation section 32 is symmetrically connected to both ends of the main feed line 31 to match the set input impedance. This set input impedance can be 50Ω. In practical applications, this microstrip antenna is connected to a 50Ω SMA connector to provide excitation to the antenna.

[0140] Among them, such as Figure 1As shown, the impedance transformation section 32 includes at least a first transformation section 321 and a second transformation section 322 of equal length but unequal width. The first transformation section 321 is symmetrically connected to both ends of the main feed line 31, and the second transformation section 322 is symmetrically connected to the first transformation section 321 at both ends of the main feed line 31. The first transformation section 321, connecting the main feed line 31 and the second transformation section 322, serves as an impedance transformation element and is one of the key structures for adjusting the impedance matching of the microstrip antenna.

[0141] In order to improve the radiation capability, the lengths of the first transformation segment 321 and the second transformation segment 322 are at least 0.25×λc, where λc is the waveguide wavelength of the center frequency of the microstrip line 3.

[0142] This application also provides an antenna system, such as... Figures 18 to 22 As shown, it includes the microstrip antennas provided in any embodiment of this application, and includes at least a combination of two microstrip antennas, both of which are horizontally polarized microstrip antennas 100, such as... Figure 18 As shown; or at least two microstrip antennas are combinations of vertically polarized microstrip antennas 200, such as Figure 19 As shown; or at least two microstrip antennas are a combination of a horizontally polarized microstrip antenna 100 and a vertically polarized microstrip antenna 200, such as Figure 20 As shown.

[0143] Compared to conventional antennas or leaky cables used in the present application, the antenna system provided in this embodiment adopts a microstrip antenna including a dielectric substrate 1, a ground plane 2, and a microstrip line 3. By setting grooves 21 and stubs on the ground plane 2, the radiation performance of the microstrip line 3 is enhanced. Furthermore, by combining at least two microstrip antennas, the antenna system can have better radiation performance in narrow areas such as tunnels and alleys, thereby increasing antenna capacity and achieving uniform coverage.

[0144] In this embodiment, as Figure 20 As shown, the antenna system preferably employs a combination of a horizontally polarized microstrip antenna 100 and a vertically polarized microstrip antenna 200. Therefore, this antenna system can achieve H / V dual-polarization radiation, realize MIMO polarization diversity, enhance MIMO performance, is more suitable for narrow regions, and has good short-range deep coverage characteristics.

[0145] The antenna system includes 2 n-1 100 and 2 horizontally polarized microstrip antennas n-1 There are 200 vertically polarized microstrip antennas, where n = 1, 2, 3…k, and k is a positive integer. That is, the antenna system can include 2… n There are 100 antennas, of which the number of horizontally polarized microstrip antennas 100 and the number of vertically polarized microstrip antennas 200 are equal, each accounting for half, such as forming a 2T2R, 4T4R or higher order MIMO array.

[0146] The horizontally polarized microstrip antenna 100 and the vertically polarized microstrip antenna 200 are of equal length and are arranged side-by-side in parallel. Specifically, as shown... Figure 20 As shown, for a 2T2R MIMO array, a horizontally polarized microstrip antenna 100 and a vertically polarized microstrip antenna 200 can be arranged side by side in parallel. Meanwhile, in the length direction, as... Figure 21 As shown, the horizontally polarized microstrip antenna 100 can be connected in series with a larger number of horizontally polarized antennas via RF cable 400 and RF connector 300; for example Figure 22 As shown, the vertically polarized microstrip antenna 200 can be connected in series with more vertically polarized antennas via RF cable 400 and RF connector 300. This allows for a longer antenna to meet the needs of narrow areas such as tunnels and alleys, or large and enclosed scenarios such as stadiums and exhibition halls. The horizontally polarized microstrip antenna 100 and the vertically polarized microstrip antenna 200 at the ends can be connected to an absorption load 500 to absorb the residual power at the antenna ends, thereby eliminating reflections.

[0147] This antenna system, through the combination of multiple H / V polarized microstrip antennas, can simultaneously achieve polarization diversity and spatial diversity MIMO, significantly improving capacity and increasing radiation capability by at least 20dB.

[0148] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microstrip antenna, characterized in that, include: Dielectric substrate; A floor is disposed on one side surface of the dielectric substrate. Branches and grooves are provided on both sides of the floor. The branches and grooves are periodically arranged in the length direction of the floor, so that the microstrip antenna is formed as a horizontally polarized microstrip antenna or a vertically polarized microstrip antenna. A microstrip line is disposed on the other side surface of the dielectric substrate.

2. The microstrip antenna according to claim 1, characterized in that, The grooves are symmetrically formed on both sides of the floor in the width direction. The branches include a first branch and a second branch. The first branch is disposed in a portion of the grooves and the first branches are alternately arranged on both sides of the floor in the width direction. The second branch is disposed between two adjacent grooves and is connected to the edge of the floor. The second branch is alternately arranged on both sides of the floor in the width direction.

3. The microstrip antenna according to claim 2, characterized in that, One end of the first branch is connected to the side of the groove near the center line of the floor in the length direction, and the other end of the first branch extends in a straight line in the width direction of the floor to the edge of the dielectric substrate.

4. The microstrip antenna according to claim 3, characterized in that, The second branch includes a first segment, a second segment, and a third segment. The first segment and the third segment are respectively perpendicularly connected to the second segment. The second segment is parallel to the edges of the floor on both sides in the width direction. The ends of the first segment and the third segment away from the second segment are connected to the edge of the floor.

5. The microstrip antenna according to claim 3, characterized in that, The length of the first stub is (0.25~0.35)×λc, where λc is the waveguide wavelength of the microstrip line center frequency.

6. The microstrip antenna according to claim 2, characterized in that, Along the length of the floor, the distance between two adjacent grooves, the distance between two adjacent first branches, or the distance between two adjacent second branches is equal.

7. The microstrip antenna according to claim 6, characterized in that, Along the length of the floor, the distance between two adjacent grooves, the distance between two adjacent first branches, or the distance between two adjacent second branches is (0.35~0.65)×λc, where λc is the waveguide wavelength of the microstrip line center frequency.

8. The microstrip antenna according to claim 2, characterized in that, The distance from the side of the groove closest to the centerline of the floor in the longitudinal direction to the centerline is at least 0.20 × λc, where λc is the waveguide wavelength of the microstrip line center frequency.

9. The microstrip antenna according to claim 1, characterized in that, The grooves are symmetrically formed on both sides of the floor in the width direction; The groove includes a first groove and a second groove, and in the length direction of the floor, the first groove is located near the end of the floor, and the second groove is located on the side of the first groove away from the end of the floor; The branch includes a third branch and a fourth branch. The third branch is disposed between the first groove and the second groove, and between two adjacent second grooves, and the third branch is connected to the edge of the floor. The fourth branch is disposed in the second groove; The third and fourth branches are arranged symmetrically on both sides of the floor width direction.

10. The microstrip antenna according to claim 9, characterized in that, The width of the second groove is greater than the width of the first groove.

11. The microstrip antenna according to claim 9, characterized in that, The third branch includes a fourth segment, a fifth segment, and a sixth segment. The fourth segment and the sixth segment are respectively perpendicularly connected to the fifth segment. The fifth segment is parallel to the edges of the floor on both sides in the width direction. The ends of the fourth segment and the sixth segment away from the fifth segment are connected to the edge of the floor.

12. The microstrip antenna according to claim 11, characterized in that, The fourth branch includes a seventh segment, an eighth segment, a ninth segment, a tenth segment, and an eleventh segment. One end of the seventh segment and the eighth segment are respectively perpendicularly connected to both ends of the ninth segment. The other ends of the seventh segment and the eighth segment are respectively perpendicularly connected to the tenth segment and the eleventh segment. The tenth segment and the eleventh segment are connected to the second groove on one side near the center line of the floor in the length direction. The ninth segment is parallel to the edge of the floor and is flush with the position of the fifth segment.

13. The microstrip antenna according to claim 9, characterized in that, The distance from the side of the first slot and the second slot closest to the centerline of the floor in the length direction to the centerline is at least 0.20×λc, where λc is the waveguide wavelength of the microstrip line center frequency.

14. The microstrip antenna according to claim 9, characterized in that, Along the length of the floor, the distance between two adjacent second grooves, the distance between two adjacent third branches, or the distance between two adjacent fourth branches is equal.

15. The microstrip antenna according to claim 14, characterized in that, Along the length of the floor, the distance between two adjacent second slots, the distance between two adjacent third branches, or the distance between two adjacent fourth branches is (0.35~0.65)×λc, where λc is the waveguide wavelength of the microstrip line center frequency.

16. The microstrip antenna according to any one of claims 1-15, characterized in that, The microstrip line includes a main feed line and an impedance transformation section. The main feed line is located above or below the midline of the ground plane, and the impedance transformation section is symmetrically connected to both ends of the main feed line to match the set input impedance of 50 ohms.

17. The microstrip antenna according to claim 16, characterized in that, The impedance transformation section includes at least a first transformation section and a second transformation section with equal length and unequal width. The first transformation section is symmetrically connected to the left and right ends of the main feeder in the length direction, and the second transformation section is symmetrically connected to the outer ends of the first transformation section at both ends of the main feeder.

18. The microstrip antenna according to claim 17, characterized in that, The lengths of the first transformation segment and the second transformation segment are at least 0.25 × λc, where λc is the waveguide wavelength of the microstrip line center frequency.

19. The microstrip antenna according to any one of claims 1-15 and 17-18, characterized in that, The dielectric substrate is a flexible dielectric substrate.

20. The microstrip antenna according to claim 19, characterized in that, The dielectric substrate is made of polytetrafluoroethylene (PTFE), polyimide (PI), or polycarbonate (PC).

21. The microstrip antenna according to any one of claims 1-15, 17-18, and 20, characterized in that, The thickness of the dielectric substrate is less than or equal to 2 mm.

22. An antenna system, characterized in that, It includes at least two microstrip antennas as described in any one of claims 1-21, and includes at least two of the microstrip antennas being combinations of horizontally polarized microstrip antennas, or at least two of the microstrip antennas being combinations of vertically polarized microstrip antennas, or at least two of the microstrip antennas being combinations of horizontally polarized microstrip antennas and vertically polarized microstrip antennas.

23. The antenna system according to claim 22, characterized in that, The antenna system includes 2 n-1 The horizontally polarized microstrip antenna and 2 n-1 The vertically polarized microstrip antennas are defined as follows, where n = 1, 2, 3…k, and k is a positive integer; The horizontally polarized microstrip antenna and the vertically polarized microstrip antenna are of equal length and are arranged side by side in parallel.

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