A multi-band microstrip patch antenna and a design method thereof

Abstract

This invention discloses a design method for a multi-band microstrip patch antenna for 5G millimeter-wave wireless communication, comprising: taking an FR-4 lossy dielectric substrate as the object, setting parameter values ​​for the relative permittivity εr, resonant frequency fr, and substrate thickness h, and calculating the antenna's geometric properties by simplifying the resonant cavity model; optimizing the required geometric dimensions and obtaining a slotless antenna model based on the expected performance; gradually introducing slots into the patch to form an open wrench-shaped structure, monitoring radiation performance during the process, and adjusting the slot size based on the observed radiation response; adding a rectangular defective ground gap in a portion of the ground layer to improve the antenna's impedance matching and bandwidth; and adjusting the slot position to provide optimal performance for applications below 6 GHz. Simulation results show that the antenna achieves significant size reduction while maintaining the necessary performance characteristics for Sub-6 GHz 5G wireless communication devices.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a multi-band microstrip patch antenna for 5G millimeter-wave wireless communication and its design method. Background Technology

[0002] As wireless communication technology evolves from 1G to 5G, the demand for frequency band resources continues to rise. 5G communication focuses on the millimeter-wave band, which typically ranges from 24.25GHz to 52.6GHz. The millimeter-wave band has the advantages of large bandwidth and high data transmission rate, but it also faces many challenges, such as severe atmospheric absorption and attenuation of signals during transmission, which places higher demands on antenna design.

[0003] Traditional microstrip antennas have been widely used in wireless communication due to their advantages such as low profile, light weight, low cost, and ease of integration. However, traditional microstrip antennas have some limitations in 5G millimeter-wave band applications, such as narrow bandwidth, low gain, and low radiation efficiency. These problems limit their performance in 5G high-frequency communication and make it difficult to meet the requirements of modern wireless communication systems for high gain, wide bandwidth, and high efficiency. Therefore, researching and developing multi-band microstrip patch antennas suitable for 5G millimeter-wave bands has become an urgent task. These antennas need to achieve good matching and radiation performance across multiple frequency bands to adapt to the application requirements of 5G systems in different frequency bands; at the same time, they also need to have a compact structure to facilitate integration into various communication devices, such as smartphones and base stations, within limited space. In 5G communication systems, antennas are key components for signal transmission, and their performance directly affects the efficiency and stability of the entire communication system. By optimizing antenna design and improving its bandwidth, gain, and radiation efficiency in the millimeter-wave band, the communication quality and coverage of 5G systems can be significantly improved. Furthermore, with the development of Internet of Things (IoT) technology, a large number of devices need to access 5G networks, placing higher demands on the miniaturization and high performance of antennas. Traditional microstrip antennas have limitations in bandwidth, gain, and efficiency, making it difficult to meet the multi-band application requirements of 5G high-frequency bands. Therefore, it is necessary to design a multi-band microstrip patch antenna capable of covering the 5G millimeter-wave band to improve the performance and efficiency of communication systems. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a multi-band microstrip patch antenna for 5G millimeter-wave wireless communication and its design method, thereby providing a high-performance antenna solution for 5G millimeter-wave communication.

[0005] The technical solution provided by this invention is as follows: A design method for a multi-band microstrip patch antenna for 5G millimeter-wave wireless communication, the method comprising the following steps: Modeling a small open-end wrench-shaped patch antenna using CST software. (1) Taking FR-4 lossy dielectric substrate as the object, set the parameter values ​​of relative permittivity εr, resonant frequency fr and substrate thickness h, and calculate the geometric properties of the antenna by simplifying the resonant cavity model; (2) Based on the expected performance, optimize to obtain the required geometric dimensions and slotless antenna model; (3) Grooves are gradually introduced into the patch to form an open wrench-shaped structure, during which the radiation performance is monitored and the size of the grooves is adjusted according to the observed radiation response; (4) A rectangular defective ground gap is added to part of the grounding layer to improve the impedance matching and bandwidth of the antenna; (5) Adjust the position of the slot to provide optimal performance for applications below 6 GHz.

[0006] Preferably, in step (1), the simplified resonant cavity model is specifically defined by the following equation: (1); Where a represents the patch radius, h represents the thickness of the dielectric substrate, εr is the relative permittivity of the substrate, and F is a logarithmic function; (2); Where fr is the resonant frequency; The length of the base is: (3); The base width is: (4).

[0007] Preferably, in step (1), the relative permittivity εr is 4.3, the resonant frequency fr is 3GHz, and the substrate thickness h is 1.6mm.

[0008] Preferably, step (2) employs and progressively optimizes various electromagnetic control strategies to achieve broadband and good impedance matching under miniaturized size conditions. First, a slotted structure of specific shape and size is introduced on the radiating patch. By changing the current distribution on the patch surface, the equivalent current path is extended and additional resonant modes are introduced, thereby enabling the antenna to generate multiple resonances at different frequency points, effectively broadening the operating bandwidth and reducing reflection loss. The width, length, and position of the slot are gradually adjusted through parameter scanning to precisely control the resonant frequency and the coupling relationship between each resonance. Second, a partial ground plane structure is used to replace the traditional complete ground plane, and a rectangular defective ground structure (DGS) is loaded on the ground plane. By weakening the continuity of the ground plane current and enhancing the coupling effect between the patch and the ground, the input impedance matching is improved and the impedance bandwidth is further expanded. In addition, the length of the partial ground plane and the size and position of the defective ground structure are also repeatedly optimized to achieve a synergistic effect on bandwidth improvement and return loss suppression within the target Sub-6GHz frequency band. Ultimately, by combining patch slotting with a partial grounding structure, a comprehensive performance improvement in multi-resonance, broadband, and high efficiency was achieved without increasing antenna size or introducing complex multi-layer structures.

[0009] Preferably, the proportional relationship between the key dimensions in the antenna is as follows: A. The ratio of the outer radius Rp of the patch to the radius R1 of the groove: Rp:R1=6.7:2≈3.35:1; B. The ratio of the distance L1 from the center of the slot to the center of the patch to the patch radius Rp: L1:Rp=5:6.7≈0.75:1; C. The ratio of the defect gap length Lgi to the grounding plane length Lg: Lgi:Lg=4:14.5≈0.28:1; D. Aspect ratio of substrate: Ls:Ws=32:24=4:3; Among them, the machining tolerance for all linear dimensions can be ±0.05mm; the tolerance for the critical ratio Rp / R1 can be ±5%.

[0010] Preferably, the radiating patch and the grounding layer of the slotted portion are made of annealed copper with a thickness of 0.035 mm.

[0011] This invention overcomes the shortcomings of existing technologies and provides a solution for 5G Sub-6GHz broadband and miniaturized applications. By introducing an open-end wrench-shaped radiating patch and a slotted grounding structure (DGS) to a traditional microstrip patch antenna, it achieves multiple resonances and a wide impedance bandwidth within a limited size. The technical principle lies in using the wrench-shaped asymmetrical curved patch to extend the equivalent current path and excite multiple resonant modes. Simultaneously, the patch slots and rectangular defect slots in the ground plane enhance electromagnetic coupling and improve impedance matching, thereby significantly widening the operating bandwidth and reducing reflection loss. The innovations of this design are mainly reflected in: the first introduction of an open-end wrench-shaped structure into a microstrip patch antenna, achieving synergistic modulation of resonant characteristics through "shape loading + ground structure defects"; achieving an ultra-wide impedance bandwidth (approximately 3.2GHz) of 2.6~5.8GHz and an extremely low reflection coefficient on a low-cost FR-4 substrate; and balancing high radiation efficiency and stable directivity within a compact size. Its key technical features include: fine optimization of the geometric parameters of the wrench-shaped patch to control multimode resonance, joint adjustment of impedance and bandwidth by the location and size of partial grounding and defect slot, matching design of 50Ω microstrip feeder and patch, and system trade-offs between size, bandwidth, efficiency and gain, making the antenna suitable for various Sub-6GHz wireless communication scenarios such as 5G, WiMAX and Wi-Fi.

[0012] The beneficial effects of this invention after adopting the above technical solution are as follows: This invention designs an open-end wrench-shaped patch antenna (multi-band microstrip patch antenna) with dimensions of 24×32×1.6mm³, and simulated it using ANSYS 2020 software to achieve operation in the Sub-6GHz 5G band. The antenna is fed by a 50Ω microstrip feed line and etched onto an FR-4 lossy dielectric substrate with a height of 1.6mm, a relative permittivity of 4.3, and a loss tangent of 0.025. Simulation results show that the use of a slotted patch and defect structure improves the antenna's bandwidth and impedance matching. The antenna has two resonant frequencies of 3GHz and 4.55GHz, with return losses of -58.5dB and -28.4dB, respectively. This antenna covers a wide impedance bandwidth of 3.2GHz, with a frequency range from 2.6 to 5.8GHz, covering multiple key frequency bands within the Sub-6GHz band used for different 5G applications. Within this frequency range, a maximum gain of 2.90 dB, a directivity of 4.13 dBi, and a radiation efficiency of 85.7% were achieved. Significant size reduction was realized while maintaining the necessary performance characteristics for Sub-6 GHz 5G wireless communication devices. Using this antenna as an experimental prototype, the measured return loss results showed good agreement with the simulation results. Attached Figure Description

[0013] Figures 1-4 This is a diagram of the antenna structure of the present invention; wherein, Figure 1 This is the front view. Figure 2 This is a magnified view of a portion of the front view. Figure 3 It is a side view. Figure 4 This is the bottom view; Figure 5 This is a graph showing the variation of the return loss at the operating frequency of the designed antenna. Figure 6 This is the voltage standing wave ratio (VSWR) curve of the designed patch antenna versus frequency; Figure 7 This is the far-field gain pattern of the antenna at 3 GHz; Figure 8 This is the far-field gain pattern of the antenna at 4.5 GHz. Detailed Implementation

[0014] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0015] This invention designs a small, open-end, wrench-shaped circular microstrip patch antenna on a low-loss FR-4 (lossy) substrate and performs simulations. The antenna exhibits a relative permittivity εr = 4.3 and a tangent loss tanδ = 0.025. The substrate, with a height of 1.6 mm, is used for structured antenna design and simulations were performed using ANSYS 2020 software. The antenna was initially constructed to have a resonant frequency of 3 GHz. The radiating patch and the grounding layer of the slotted portion are made of annealed copper with a thickness of 0.035 mm. The final measured dimensions of the wrench-shaped patch antenna are 24 × 32 × 1.6 mm³. A microstrip feeder provides microwave power to the antenna. Front, rear, side, and enlarged views of the antenna structure of this invention are shown below. Figures 1-4 As shown.

[0016] I. Antenna Parameter Design Calculation 1. Surface Mount Design: (1); Where a represents the patch radius, h represents the thickness of the dielectric substrate, εr is the relative permittivity of the substrate, and F is a logarithmic function; (2); Where fr is the resonant frequency; The length of the base is: (3); The base width is: (4).

[0017] A small open-end wrench-shaped patch antenna was modeled using CST software. The design process of the antenna was divided into several steps. First, the dielectric constant εr, resonant frequency fr (in GHz), and substrate thickness h (in mm) were assumed to be known. Using these parameters, the geometric properties of the antenna were calculated by simplifying the resonant cavity model equations (1)-(4). Then, the performance required for the intended application was achieved by using and modifying various strategies, including the use of slots and partial ground planes. For 5G applications, the design started with a slotless antenna model with optimized geometry. Subsequently, slots were gradually introduced into the patch to form an open-end wrench-shaped structure. After each step, the radiation performance was carefully monitored, and the size (width and radius) of the slots was adjusted according to the observed radiation response. The feed wire was 2.83 × 18 mm², the feed wire diameter was 6.7 mm, and the shape of the transmitting patch was wrench-shaped. A rectangular slot (defective ground structure) was added to the partial ground plane, with an optimal size of 3 mm wide and 4 mm long, which improved the impedance matching and bandwidth of the antenna. The slot's position has been adjusted to provide optimal performance for applications below 6GHz, such as... Figures 1-4 The images show the front view, magnified view, rear view, and side view of this antenna structure. The dimensions of these patch slots and the values ​​of other recommended design parameters for the miniature patch antenna are given in Table 1.

[0018] Table 1 Optimized design parameters for the antenna structure .

[0019] 2. Proportional relationships between key dimensions A. The ratio of the outer radius Rp of the patch to the radius R1 of the slot: Rp:R1 = 6.7:2 ≈ 3.35:1 B. The ratio of the distance L1 from the center of the slot to the center of the patch to the patch radius Rp: L1:Rp = 5:6.7 ≈ 0.75:1 C. The ratio of the defect gap length Lgi to the grounding plane length Lg: Lgi:Lg = 4:14.5 ≈ 0.28:1 D. Aspect ratio of substrate: Ls:Ws=32:24=4:3 The machining tolerance for all the above linear dimensions can be ±0.05mm; the tolerance for the critical ratio Rp / R1 can be ±5%.

[0020] II. Working Principle and Simulation Verification 1. Working principle This antenna achieves multi-band operation within the 2.6–5.8 GHz frequency range through a combination of rectangular and circular patches. By adjusting the size and shape of the patches, the resonant frequencies of different patches are controlled, thereby covering the required 5G millimeter-wave frequency band. The optimized antenna structure creates strong coupling between different patches, expanding the antenna bandwidth and improving gain and radiation efficiency.

[0021] 2. Simulation Verification The S-parameter curve reflects the return loss at port 1. The variation within the frequency scanning range is shown in the curves. The curves reveal that the antenna exhibits low reflection characteristics at multiple frequency points, with significant resonant points appearing near 3 GHz and 4.55 GHz. The reflection coefficients are all below -10 dB, indicating good impedance matching in these frequency bands. This demonstrates good return loss and acceptable impedance matching performance, ensuring reasonable transmission efficiency.

[0022] Figure 6 The voltage standing wave ratio (VSWR) of the designed patch antenna versus frequency is shown. At 3.5 GHz, the VSWR is 1.79. The very low VSWR of 1.79 at 3.5 GHz indicates good impedance matching and minimal power loss due to reflection. This demonstrates highly efficient signal transmission and reception at this frequency, making it ideal for 5G applications requiring reliable communication in the Sub-6 GHz range.

[0023] The far-field gain modes of the antenna shown are as follows at 3 GHz and 4.5 GHz: Figure 7 , 8 As shown. This study did not explicitly resolve or demonstrate the cross-polarization component, which is crucial for evaluating polarization purity and overall performance. The obtained main lobe amplitudes were 2.15 dBV / m at 3 GHz and 2.75 dBV / m at 4.5 GHz. The lobe directions were 166 kHz and 148 kHz, the 3 dB angular beamwidths (or half-power beamwidths) were 93.9 kHz and 90.7 kHz, and the sidelobe levels were -1.9 dB and -4.4 dB at these resonant frequencies. The observed radiation pattern indicates low sidelobe levels, ensuring focused energy delivery in the desired direction while minimizing energy leakage in the undesired direction. The minimal cross-polarization level achieved a cross-polarization discrimination value exceeding 12 dB, indicating that the co-polarization component is much stronger than the cross-polarization component, implying good polarization purity and meeting the requirements of polarization-specific applications in 5G networks.

[0024] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A design method of a multi-band microstrip patch antenna for 5G millimeter wave wireless communication, characterized in that, The method involves modeling a small open-end wrench-shaped patch antenna using CST software, specifically including the following steps: (1) Taking FR-4 lossy dielectric substrate as the object, set the parameter values ​​of relative permittivity εr, resonant frequency fr and substrate thickness h, and calculate the geometric properties of the antenna by simplifying the resonant cavity model; (2) Based on the expected performance, optimize to obtain the required geometric dimensions and slotless antenna model; (3) Grooves are gradually introduced into the patch to form an open wrench-shaped structure, during which the radiation performance is monitored and the size of the grooves is adjusted according to the observed radiation response; (4) A rectangular defective ground gap is added to part of the grounding layer to improve the impedance matching and bandwidth of the antenna; (5) Adjust the position of the slot to provide optimal performance for applications below 6 GHz.

2. The method of claim 1, wherein, In step (1), the simplified resonant cavity model is specifically represented by the following equation: （1） Where a represents the patch radius, h represents the thickness of the dielectric substrate, εr is the relative permittivity of the substrate, and F is a logarithmic function; （2） Where fr is the resonant frequency; The length of the base is: （3） The base width is: （4）。 3. The method of claim 1, wherein, In step (1), the relative dielectric constant ε r is 4.3, the resonance frequency fr is 3 GHz, and the substrate thickness h is 1.6 mm.

4. The method of claim 1, wherein, Step (2) specifically includes the following steps: (2-1) Introduce a slotted structure of a specific shape and size on the radiating patch, and extend the equivalent current path and introduce additional resonant modes by changing the current distribution on the patch surface; wherein the width, length and position of the slot are gradually adjusted by parameter scanning to precisely control the resonant frequency and the coupling relationship between each resonator. (2-2) A partial ground plane structure is used to replace the traditional complete ground plane, and a rectangular defect groove is loaded on the ground plane; (2-3) The length of part of the ground plane and the size and location of the defect slot are repeatedly optimized so that they can play a synergistic role in bandwidth improvement and return loss suppression in the target Sub-6GHz frequency band.

5. The method as described in claim 1, characterized in that, The proportional relationship between the key dimensions of the antenna is as follows: A. Outer radius of the patch With groove radius The ratio: ; B. Distance from the center of the slot to the center of the patch panel With patch radius The ratio: ; C. Defective ground gap length Length of ground plane The ratio: ; D. Aspect ratio of substrate: ; Among them, the machining tolerance for all linear dimensions can be ±0.05mm; key proportions The tolerance can be ±5%.

6. The method as described in claim 1, characterized in that, The radiating patch and the grounding layer of the slotted portion are made of annealed copper with a thickness of 0.035 mm.

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