Broadband miniaturized microstrip antenna applied to wireless terminal equipment

Abstract

The invention discloses a broadband miniaturized microstrip antenna applied to wireless terminal equipment, and the structure of the antenna comprises double layers of dielectric substrates, a coupling metal patch layer disposed on the upper surface of the first layer of first dielectric substrate, and a second layer of second dielectric substrate stacked on the first layer of first dielectric substrate. The radiation metal patch layer is arranged on the upper surface of the second dielectric substrate on the second layer and is etched with a U-shaped groove which is nested inside and outside, the grounding metal plate layer is arranged below the air layer on the first layer and is etched with an L-shaped groove, and a feed source point connected to the coupling metal patch layer is arranged on a grounding metal patch. The microstrip antenna provided by the invention is compact in structure and small in size, is easy to be integrated in a small wireless terminal device, can work in two working frequency bands of 2.45 GHz-2. 76 GHz and 3.22 GHz-4. 56 GHz at the same time, and can cover N41 / N77 / N78 and other core communication frequency bands in 5G Sub-6.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a broadband miniaturized microstrip antenna applied to wireless terminal equipment. Background Art

[0002] With the rapid development of wireless communication technology and the continuous maturity of mobile Internet and Internet of Things technology, users have increasingly higher requirements for mobile terminal devices in terms of miniaturization, low power consumption and multi-functions. Antennas, as key components of wireless communication systems, face higher requirements because their performance affects the entire communication system. Microstrip antennas are widely used in wireless terminal devices due to their advantages such as light weight, small size, easy integration and low cost. However, traditional microstrip antennas have problems such as narrow bandwidth, low gain, insufficient radiation efficiency and large physical size when working at low frequencies, making it difficult to meet the needs of modern wireless terminal devices. Summary of the Invention

[0003] This specification provides a broadband miniaturized microstrip antenna for use in wireless terminal equipment, to overcome at least one technical problem existing in the related art.

[0004] The embodiments of this specification provide a broadband miniaturized microstrip antenna for use in wireless terminal devices, including:

[0005] A metal grounding layer, the metal grounding layer comprising a grounding plate metal patch having an L-shaped defective ground structure etched thereon, the L-shaped defective ground structure being composed of orthogonal horizontal strip grooves and vertical strip grooves; a first dielectric substrate and a second dielectric substrate being stacked in sequence on an upper surface of the metal grounding layer; wherein the dielectric constant of the first dielectric substrate is less than a first predetermined threshold, the dielectric constant of the second dielectric substrate is greater than a second predetermined threshold, and the first predetermined threshold is less than the second predetermined threshold;

[0006] A coupling metal patch is provided between the first dielectric substrate and the second dielectric substrate, and a metal radiation patch is mounted on the upper surface of the second dielectric substrate. The metal radiation patch is etched with a double U-shaped groove structure nested inside and outside;

[0007] A metal feeding post is vertically passed through the first dielectric substrate, a first end of the metal feeding post is electrically connected to the coupling metal patch, and a second end of the metal feeding post is electrically connected to a feeding port provided on the metal ground layer; a feeding line is provided in the first dielectric substrate, and the feeding line is connected to the feeding port through the metal feeding post;

[0008] The coupling metal patch partially overlaps with the metal radiation patch in a vertical direction to achieve coupled feeding and electromagnetic waves are radiated by the metal radiation patch.

[0009] In some optional embodiments, the inner and outer nested double U-shaped groove structures on the metal radiation patch are symmetrically distributed in the plane center, and the opening directions of the two U-shaped grooves are consistent, and the inner U-shaped groove and the outer U-shaped groove form a nested gap in the horizontal direction.

[0010] In some optional embodiments, the coupling metal patch is arranged on the upper surface of the first dielectric substrate and adheres to the lower surface of the second dielectric substrate, the metal radiation patch completely covers the corresponding area of ​​the upper surface of the second dielectric substrate, and the overlapping area of ​​the two in the vertical projection direction forms a coupling feeding interval.

[0011] In some optional embodiments, the L-shaped defect ground structure on the metal grounding layer is located directly above the feeding port, the horizontal strip groove extends along the length direction of the metal grounding layer, and the vertical strip groove extends along the width direction of the metal grounding layer, and the connection node between the two corresponds to the projection position of the feeding port.

[0012] In some optional embodiments, the thickness of the second dielectric substrate is less than that of the first dielectric substrate, and the two are made of different materials; the thickness of the second dielectric substrate is 1.5 mm-1.7 mm, and the size is 60 mm×60 mm-62 mm×62 mm; the thickness of the first dielectric substrate is 7 mm-8 mm, and the size is 60 mm×60 mm-62 mm×62 mm; the size of the metal ground layer is 65 mm×65 mm-68 mm×68 mm.

[0013] In some optional embodiments, the coupling metal patch is square in shape, has a size of 3.4 mm×3.4 mm-3.7 mm×3.7 mm, and edges of both the metal radiation patch and the coupling metal patch are aligned with the same side of the second dielectric substrate.

[0014] In some optional embodiments, the size of the metal radiation patch is 28.5 mm×15 mm.

[0015] In some optional embodiments, the metal feeding post has a diameter of 1.27 mm and a length of 7.5 mm; the metal feeding post only passes through the first dielectric substrate to connect to the coupling metal patch, and does not contact the metal radiation patch or the second dielectric substrate.

[0016] In some optional embodiments, the length and width of the horizontal strip groove and the vertical strip groove of the L-shaped defective ground structure are the same, wherein the length is 18mm-20mm and the width is 10mm-14mm.

[0017] In some optional embodiments, the double U-shaped groove structure includes an inner U-shaped groove and an outer U-shaped groove, wherein the inner U-shaped groove is composed of a third vertical groove, a fourth vertical groove and a seventh vertical groove connecting the two; the outer U-shaped groove is composed of a fifth vertical groove, a sixth vertical groove and an eighth vertical groove connecting the two; all groove widths are 0.4mm-0.6mm, and the double U-shaped grooves are symmetrical about the axis of the metal radiation patch and have the same opening direction.

[0018] One embodiment of this specification can achieve at least the following beneficial effects:

[0019] 1. The broadband miniaturized microstrip antenna for wireless terminal devices proposed in this invention has a compact structure, is easy to integrate, is small in size, and is easy to process and manufacture. The feeding structure adopts a coaxial feeding method with spatial coupling feeding, which can reduce the complex feeding circuit design. The use of a first dielectric substrate and a common second dielectric substrate can reduce costs and manufacturing difficulty, facilitating the integrated application of the antenna in various wireless terminal devices.

[0020] 2. The present invention proposes a broadband miniaturized microstrip antenna for wireless terminal devices. Based on the meandering technology, a double U-shaped groove structure is etched on the radiating metal patch, which can change the effective path length of the current. While ensuring the miniaturization of the antenna, it also has a wider operating frequency band. It can simultaneously operate in the 2.45GHz-2.76GHz and 3.22GHz-4.56GHz frequency bands, and the operating frequency band can cover the commonly used communication frequency bands in 5G Sub6. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of this specification or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A side view of a broadband miniaturized microstrip antenna for wireless terminal equipment provided by the present invention;

[0023] Figure 2 A top view of the broadband miniaturized microstrip antenna provided by the present invention for use in wireless terminal equipment;

[0024] Figure 3 A schematic diagram of a ground plate metal patch in a broadband miniaturized microstrip antenna for wireless terminal equipment provided by the present invention;

[0025] Figure 4A curve chart showing the reflection coefficient simulation results of the broadband miniaturized microstrip antenna applied to wireless terminal equipment provided by the present invention;

[0026] Figure 5 Comparison of the radiation patterns of XOZ and YOZ of the broadband miniaturized microstrip antenna for wireless terminal devices provided by the present invention operating at a frequency of 2.5 GHz;

[0027] Figure 6 Comparison of the XOZ and YOZ radiation patterns of the broadband miniaturized microstrip antenna for wireless terminal devices provided by the present invention operating at a frequency of 3 GHz;

[0028] Figure 7 Comparison of the radiation patterns of XOZ and YOZ of the broadband miniaturized microstrip antenna for wireless terminal devices provided by the present invention operating at a frequency of 3.5 GHz;

[0029] Figure 8 A comparison diagram of the XOZ and YOZ radiation patterns of the broadband miniaturized microstrip antenna for wireless terminal devices provided by the present invention operating at a frequency of 4 GHz;

[0030] Figure 9 The reflection coefficient of the broadband miniaturized microstrip antenna designed by the present invention is |S 11 |Graph of changes with frequency;

[0031] Figure 10 The 3D total gain pattern of the broadband miniaturized microstrip antenna designed for the present invention in the first case;

[0032] Figure 11 The 3D total gain pattern of the broadband miniaturized microstrip antenna designed for the present invention in the second case;

[0033] Figure 12 The 3D total gain pattern of the broadband miniaturized microstrip antenna designed for the present invention in the third case;

[0034] Figure 13 3D total gain pattern of the broadband miniaturized microstrip antenna designed for the present invention in the fourth case.

[0035] Among them, 1 represents a metal radiation patch, 2 represents a second dielectric substrate, 3 represents a coupling metal patch, 4 represents a metal feeding column, 5 represents a first dielectric substrate, 6 represents a metal grounding layer, and 7 represents a feeding port. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 1 This is a side view of a broadband miniaturized microstrip antenna for wireless terminal equipment provided by the present invention. Figure 2 is the top view of the microstrip antenna. Figure 3 Figure 1 is a schematic diagram of the metal patch on the ground plane of the microstrip antenna. Figure 1As shown, the microstrip antenna includes a metal ground layer 6, which includes a ground plate metal patch, on which an L-shaped defect ground structure is etched. The L-shaped defect ground structure is composed of horizontal strip grooves and vertical strip grooves orthogonal to each other. A first dielectric substrate 5 and a second dielectric substrate 2 are stacked in sequence on the upper surface of the metal ground layer 6, wherein the dielectric constant of the first dielectric substrate 5 is less than a first predetermined threshold, the dielectric constant of the second dielectric substrate 2 is greater than a second predetermined threshold, and the first predetermined threshold is less than the second predetermined threshold; wherein a coupling metal patch 3 is provided between the first dielectric substrate 5 and the second dielectric substrate 2, and a coupling metal patch 3 is provided on the second dielectric substrate 2. A metal radiating patch 1 is mounted on the upper surface of the board 2, and the metal radiating patch 1 is etched with a double U-shaped groove structure nested inside and outside; a metal feeding post 4 is vertically passed through the first dielectric substrate 5, the first end of the metal feeding post 4 is electrically connected to the coupling metal patch 3, and the second end of the metal feeding post 4 is electrically connected to the feeding port 7 provided on the metal ground layer 6; a feeding line (not shown in the figure) is provided in the first dielectric substrate 5, and the feeding line is connected to the feeding port 7 through the metal feeding post 4; the coupling metal patch 3 and the metal radiating patch 1 partially overlap in the vertical direction to achieve coupled feeding and radiate electromagnetic waves from the metal radiating patch 1. In the above scheme, the first and second predetermined thresholds are demarcations set based on the antenna's functional requirements, with the first predetermined threshold being lower than the second predetermined threshold. This distinguishes between a first dielectric substrate with a low dielectric constant and a second dielectric substrate with a relatively high dielectric constant, ensuring that a dielectric gradient is formed between the two, each assuming different functions. Specifically, the first dielectric substrate 5, due to its low dielectric constant and low loss characteristics, is suitable as a dielectric layer for coupled energy transmission; while the second dielectric substrate 2, due to its relatively high dielectric constant, is suitable for supporting the metal radiating patch 1 and regulating its surface current distribution, synergistically achieving broadband radiation and miniaturization of the antenna. In practical scenarios, considering that the dielectric constant of air is approximately 1 and the loss tangent is approximately 0, the first dielectric substrate 5 can be an air dielectric substrate. Alternatively, it can include polytetrafluoroethylene (Teflon, dielectric constant approximately 2.1) or foam materials (dielectric constant approximately 1.1-1.3). These materials have low dielectric constants and low loss, which can reduce energy loss during coupled transmission. As for the second dielectric substrate, considering that the dielectric constant of FR4 medium is ≈4.4, the second dielectric substrate 2 can be an FR4 dielectric substrate. In addition, it can also include ceramic composite materials (dielectric constant ≈6-10), high-frequency epoxy substrates (dielectric constant ≈3.5-4.2), etc. These materials have a high dielectric constant and can provide stable support for the metal radiation patch. The propagation speed of electromagnetic waves can be controlled through the dielectric properties, and the resonant frequency can be adjusted in conjunction with the slot structure of the radiation patch.

[0038] like Figure 3 As shown, Figure 3Schematic diagram of the ground plate metal patch in the microstrip antenna, on which an L-shaped defect structure is etched. The L-shaped defect structure is composed of horizontal strip grooves and vertical strip grooves orthogonal to each other. The length L of the horizontal strip groove and the vertical strip groove is g and width w g Same, where the length L g Can be 19mm, width w g It can be 12mm.

[0039] The metal radiation patch 1 is etched with a double U-shaped groove structure nested inside and outside, such as Figure 2 As shown, Figure 2 is the side view of the microstrip antenna. Figure 2 It can be seen that the structure of the double U-shaped groove structure includes an inner U-shaped groove and an outer U-shaped groove, wherein the inner U-shaped groove is composed of a third vertical groove, a fourth vertical groove and a seventh vertical groove connecting the two; the outer U-shaped groove is composed of a fifth vertical groove, a sixth vertical groove and an eighth vertical groove connecting the two; all groove widths are 0.4-0.6mm, such as 0.5mm, and the double U-shaped grooves are symmetrical about the axis of the metal radiation patch and have the same opening direction.

[0040] Figure 2 The yellow area in the middle is the metal ground layer 6, which measures 67 mm × 67 mm. An L-shaped defect structure is etched on its surface and serves as the reference ground plane for the antenna. The green area is the metal radiation patch 1, which is mounted on the top surface of the second dielectric substrate 2 (the second dielectric substrate measures 60 mm × 60 mm and is 1.6 mm thick).

[0041] A metal feeding post 4 vertically penetrates the first dielectric substrate 5. The first end of the metal feeding post 4 is electrically connected to the coupling metal patch 3, and the second end of the metal feeding post 4 is electrically connected to the feeding port 7 provided on the metal ground layer 6. A feeding line is provided in the first dielectric substrate 5 and connected to the feeding port 7 via the metal feeding post 4. The coupling metal patch 3 partially overlaps with the metal radiating patch 1 in the vertical direction to achieve coupled feeding and radiate electromagnetic waves from the metal radiating patch 1.

[0042] The second dielectric substrate 2 is thinner than the first dielectric substrate 5, and the two are made of different materials. The thickness of the second dielectric substrate 2 can range from 1.5 mm to 1.7 mm, such as 1.6 mm, and the dimensions can range from 60 mm × 60 mm to 62 mm × 62 mm. The thickness of the first dielectric substrate 5 can range from 7 mm to 8 mm, such as 7.5 mm, and the dimensions can range from 60 mm × 60 mm to 62 mm × 62 mm. The dimensions of the metal ground layer 6 can range from 65 mm × 65 mm to 68 mm × 68 mm, such as 67 mm × 67 mm. The coupling metal patch 3 is square in shape and has dimensions ranging from 3.4 mm × 3.4 mm to 3.7 mm × 3.7 mm, such as 3.5 mm × 3.5 mm. The edges of the metal radiating patch 1 and the coupling metal patch 3 are aligned with the same side of the second dielectric substrate 2. The dimensions of the metal radiating patch 1 can be 28.5 mm × 15 mm. The metal feeding post 4 may have a diameter of 1.27 mm and a length of 7.5 mm. The metal feeding post 4 only passes through the first dielectric substrate 5 to connect to the coupling metal patch 3 and does not contact the metal radiation patch 1 or the second dielectric substrate 2 .

[0043] In the above technical solution, if Figure 2As shown, the inner and outer nested double-U groove structure on the metal radiation patch 1 is symmetrically distributed around the plane center, and the opening directions of the two U grooves are the same. A nested gap is formed between the inner U groove and the outer U groove in the horizontal direction. The coupling metal patch 3 is disposed on the upper surface of the first dielectric substrate 5 and adheres to the lower surface of the second dielectric substrate 2. The metal radiation patch 1 completely covers the corresponding area on the upper surface of the second dielectric substrate 2, and the overlapping area of the two in the vertical projection direction forms a coupling feeding interval. When an electrical signal is applied to the coupling metal patch 3, it will excite a spatial electromagnetic field. Since the radiation patch 1 and the coupling patch 3 overlap in the projection area, an alternating current will be induced in the radiation patch within this overlapping area, that is, through the "spatial coupling" of the electromagnetic field rather than direct metal connection, thereby achieving the transfer of energy from the coupling end to the radiation end. The essence of the total coupling feeding in this solution is to utilize electromagnetic induction, through the spatial electromagnetic field coupling between the two patches, to replace the traditional direct connection of metal probes / microstrip lines. This method can reduce the structural complexity, such as no need for drilling or wiring, and avoid parasitic effects introduced by direct connection, such as impedance mutation and loss, and is more conducive to the miniaturization of the antenna. At the same time, in the technical solution of this application, the L-shaped defected ground structure on the metal ground layer 6 is located directly above the feeding port 7. The horizontal strip groove extends along the length direction of the metal ground layer 6, and the vertical strip groove extends along the width direction of the metal ground layer 6. The connection node of the two corresponds to the projection position of the feeding port 7. In this solution, it can be formed by etching an L-shaped groove composed of a horizontal strip groove and a vertical strip groove on the surface of the metal ground layer 6; this L-shaped structure is located directly above the feeding port 7, that is, they spatially overlap in the vertical projection direction, so as to ensure that the electromagnetic field of the feeding port can be efficiently coupled to the defected ground structure. The two intersect vertically to form an L-shaped contour, and its connection node (the intersection of the horizontal groove and the vertical groove) coincides with the position of the vertical projection of the feeding port 7 on the metal ground layer 6. This design can make the electromagnetic field of the feeding signal concentrate and couple at the connection node, forcing the current to flow around the groove, equivalently introducing a distributed LC resonance circuit, and realizing impedance matching optimization.

[0044] Specifically, in the technical solution of the present invention, the outer U groove in the double-U groove is composed of two side vertical grooves (depth L0) and a bottom horizontal groove (width w0), and the groove width u w can be 0.5 mm, forming a "frame-type" current path and extending the current transmission distance in the low-frequency band (2.45 - 2.76 GHz). The inner U groove is nested inside the outer groove, and the depth of the vertical groove is L i (L i < L0), and the width of the bottom horizontal groove is w i (w i<w0), the slot width can also be 0.5 mm, and the high-frequency band (3.22 - 4.56 GHz) resonance is excited through a shorter current path. The depth L0 of the outer layer slot in the double U-shaped slot determines the low-frequency resonance point. The longer L0 is, the farther the equivalent current path is, and the lower the resonance frequency. The depth L of the inner layer slot i determines the high-frequency resonance point, L i is shorter, corresponding to a 3.5 GHz resonance, and cooperates with the outer layer slot to achieve dual-band coverage. The slot width u w = 0.5 mm balances the current density and loss. If it is too narrow, the ohmic loss will increase; if it is too wide, the current path will be shortened, reducing the bandwidth expansion effect. The differential design of the geometric parameters (inner and outer layer depths, widths) of the double U-shaped slot, the spatial coupling layout (Df, L2) of the feeding structure, combined with the dielectric gradient of the multi-layer dielectric (air + FR4), realizes 5G Sub-6 dual-band coverage and miniaturized integration.

[0045] In the above technical solution, two nested U-shaped slots etched on the radiation patch 1 are used to expand the current path of the antenna, broaden the bandwidth of the antenna, and at the same time reduce the resonance frequency of the antenna, realizing the miniaturization of the antenna. In order to make the antenna better cover the core communication bands (n41, n77, n78, etc.) of 5G Sub6 and also have good impedance matching, an L-shaped defected ground structure is etched on the metal ground layer 6. The present invention uses a space-coupled coaxial probe feeding method to feed the antenna. The metal coupling patch 4 and the cylindrical feeding probe form a capacitive near-field coupling feed, compensating for the distributed inductance caused by the longer feeding probe.

[0046] The microstrip antenna in this embodiment uses U-shaped slots and L-shaped slots to realize the miniaturization of the antenna and further expand the bandwidth of the antenna. The antenna in this embodiment can operate in two frequency bands of 2.45 GHz - 2.76 GHz and 3.22 GHz - 4.56 GHz, can well cover the communication bands such as n41 / n77 / n78 in 5G Sub6, and the reflection coefficients at the resonance frequency points are -18.21 dB, -18.19 dB, and -48.64 dB respectively, with good impedance matching effect. The total relative bandwidth of the antenna reaches 46.3%, and the peak gain of the antenna at the 3 GHz frequency point can reach 7.56 dB. The dielectric substrate of the antenna is made of FR4 material. Therefore, the antenna has a low design cost, a simple manufacturing process, and is easier to be integrated into various wireless terminal devices. In a possible case, the dimensions of each structure can be as shown in Table 1.

[0047] Table 1 Structure Dimension List (unit: mm)

[0048]

[0049] The inner conductor of the coaxial line passes through the feeding port 7 on the metal grounding layer 6, penetrates the first dielectric substrate 5 with a thickness of 7.5 mm, and is electrically connected to the coupling metal patch 3 with a size of 3.5 mm × 3.5 mm. The outer conductor of the coaxial line is directly connected to the metal grounding layer 6 to form a reference ground; after the RF signal is input into the coupling metal patch 3 through the inner conductor, it excites its surface current. This current generates a near-field electromagnetic field in the space above the air medium (dielectric constant ≈ 1, low loss characteristics). Due to the coupling metal patch 3 and the upper second dielectric substrate 2 (thickness 1.6 mm, dielectric constant The metal radiation patch 1 (size 28.5mm×15mm, etched with double U-shaped grooves) on 4.4) partially overlaps in the vertical direction (spacing 1.6mm, much smaller than the 85.7mm wavelength of the 3.5GHz band, and is in the near-field region). The near-field electromagnetic field of the coupled metal patch 3 transfers energy through the FR4 medium in a "near-field coupling" manner, stimulating the surface current of the radiation-coupled metal patch 1; the inner and outer nested double U-shaped grooves (groove width 0.5mm) of the radiation patch 1 extend the current path, respectively stimulating the resonant modes of 2.45GHz-2.76GHz (covering 5G n41) and 3.22GHz-4.56GHz (covering n77 and n78). The surface current oscillates in the resonant mode and is eventually radiated in the form of free-space electromagnetic waves, realizing multi-band signal transmission.

[0050] The present invention also simulates and tests the microstrip antenna designed above in the electromagnetic simulation software HFSS. The simulation results are as follows: Figures 4 to 13 As shown, they are introduced below.

[0051] Figure 4 The curve diagram of the reflection coefficient simulation results of the designed antenna is shown in Figure 2. Figure 4 The horizontal axis is frequency (GHz), and the vertical axis is reflection coefficient S11 (dB). The curve in this graph shows the impedance matching characteristics of the designed microstrip antenna in the 2.0GHz to 5.0GHz frequency band. The graph shows that the reflection coefficient S11 of the microstrip antenna in the low-frequency band of 2.45GHz-2.76GHz and the high-frequency band of 3.22GHz-4.56GHz is less than -10dB, meeting the impedance matching requirements in engineering applications. The S11 is -18.21dB at the 2.5GHz frequency point, -18.19dB at the 3.5GHz frequency point, and -48.64dB at the 4GHz frequency point, indicating excellent impedance matching at the resonant point. The graph shows that the designed microstrip antenna has a total relative bandwidth of 46.3%, which can cover core communication frequency bands such as N41 / N77 / N78 in 5G Sub-6. This performance is due to the synergistic effect of the dual U-shaped groove structure etched on the metal radiation patch and the L-shaped defect ground structure of the metal ground layer. The dual U-shaped groove structure can stimulate multi-resonant modes through the meander effect, and the L-shaped groove perturbs the ground current distribution. Together, they expand the antenna bandwidth. Figure 4The simulation results in Figure 4 verify the effectiveness of the broadband design.

[0052] Figure 5 The XOZ and YOZ radiation patterns of the microstrip antenna designed for the present invention operating at a frequency of 2.5 GHz are compared, where the XOZ plane is a horizontal plane (Y=0) and the YOZ plane is a vertical plane (X=0). The figure shows the normalized gain distribution of the antenna at different angles through polar coordinate curves. The radiation pattern of the XOZ plane is approximately circular, with the main lobe concentrated in the 0° direction (positive direction of the X-axis). The gain distribution is uniform within 360°, reflecting a nearly omnidirectional radiation characteristic in the horizontal direction, which is suitable for multi-directional signal transmission of wireless terminal devices in the horizontal plane. The radiation pattern of the YOZ plane is petal-shaped, with the main lobe concentrated in the range of 0° to 30° (positive direction of the Z-axis, above the antenna). The sidelobe level is low and the front-to-back ratio is significant, indicating that the vertical energy is mainly radiated above the antenna to reduce loss to the ground layer. This radiation characteristic stems from the synergistic effect of the dual U-shaped groove structure on the radiating metal patch and the L-shaped defective ground structure of the metal ground layer. The dual U-shaped groove optimizes current distribution through the meander effect, making the radiation in the XOZ plane uniform and the main lobe in the YOZ plane concentrated. The L-shaped defective ground structure suppresses the surface waves in the ground layer to improve the forward gain. At this time, the antenna's reflection coefficient is -18.21dB at 2.5GHz, the maximum gain in the XOZ plane is approximately 3 to 5dB, and the peak gain of the main lobe in the YOZ plane is slightly higher. The main lobe width is close to 360° in the XOZ plane and approximately 60° to 80° in the YOZ plane. This radiation pattern characteristic matches the requirements of the N41 band covering Wi-Fi and 5G Sub-6 in the 2.5GHz frequency band, verifying the optimization effect of the structural design on radiation directivity and gain.

[0053] Figure 6 The radiation patterns of the XOZ and YOZ microstrip antennas designed for the present invention operating at a frequency of 3 GHz are compared. The black dotted line represents the radiation characteristics of the XOZ surface, and the red solid line represents the radiation characteristics of the YOZ surface. Since the dual U-shaped slots of the radiating patch are symmetrical about the X-axis and the openings are along the negative direction of the X-axis, the current distribution in the X direction is more symmetrical. Therefore, the main lobe of the XOZ surface radiation pattern is concentrated and the side lobes are well suppressed. The YOZ surface has a slightly wider main lobe due to the width dimension (14.5 mm) and the slot structure, but both exhibit stable directional radiation patterns. This verifies the radiation performance of the dual U-shaped slot and coupled feed design at 3 GHz (belonging to the 3.22 GHz-4.56 GHz operating frequency band), supporting the antenna's signal directional transmission capability in the 5G Sub-6 core frequency band.

[0054] Figure 7The broadband miniaturized microstrip antenna designed for the present invention operates at a frequency of 3.5 GHz (belonging to the 3.22 GHz-4.56 GHz operating frequency band). The radiation patterns of the XOZ plane (including the X-axis and the Z-axis, corresponding to the length direction of the radiation patch) and the YOZ plane (including the Y-axis and the Z-axis, corresponding to the width direction of the radiation patch) are compared. The black dotted line represents the radiation characteristics of the XOZ plane, and the red solid line represents the radiation characteristics of the YOZ plane. Since the double U-shaped slots of the radiation patch are symmetrical about the X-axis and the openings are along the negative direction of the X-axis, and the coupling metal patch is aligned with the edge of the radiation patch, the current distribution in the X direction is more symmetrical. Therefore, the main lobe of the XOZ plane radiation pattern is concentrated and the side lobe suppression is better. The main lobe of the YOZ plane is slightly wider due to the width dimension (14.5 mm) and structure, but both present a stable directional radiation pattern, verifying the radiation performance of the double U-shaped slot and spatial coupling feed design at 3.5 GHz, supporting the antenna to transmit signals efficiently in the 5GSub-6 core frequency band (such as n77 / n78).

[0055] Figure 8 The radiation patterns of the microstrip antenna designed for the present invention are compared in the XOZ plane (including the X-axis and Z-axis, corresponding to the length direction of the radiation patch) and the YOZ plane (including the Y-axis and Z-axis, corresponding to the width direction of the radiation patch) at the 4 GHz frequency (belonging to the 3.22 GHz-4.56 GHz operating frequency band). The black dotted line represents the radiation characteristics of the XOZ plane, and the red dotted line represents the radiation characteristics of the YOZ plane. Since the double U-shaped slots of the radiation patch are symmetrical about the X-axis and the openings are along the negative direction of the X-axis, and the coupling metal patch is aligned with the edge of the radiation patch, the current distribution in the X direction is more symmetrical. Therefore, the main lobe of the XOZ plane radiation pattern is concentrated and the side lobe is well suppressed. The main lobe of the YOZ plane is slightly wider due to the width dimension (14.5 mm) and structure, but both show stable directional radiation patterns, verifying the radiation performance of the double U-shaped slot and spatial coupling feed design at the 4 GHz frequency, supporting the antenna to transmit signals efficiently in the 5G Sub-6 core frequency band (such as n77 / n78).

[0056] Figure 9 This is a curve showing the reflection coefficient |S11| of the microstrip antenna designed in this invention as a function of frequency. The horizontal axis covers 2.0-5.0 GHz, and the vertical axis quantifies the ratio of reflected power to incident power in dB (the larger the absolute negative value, the better the impedance matching). The curve shows two core resonant ranges: the first is 2.45-2.76 GHz (corresponding to the 5G n41 band), where |S11| is the reflection coefficient of the microstrip antenna designed in this invention. The reflection coefficient |S11| is the reflection coefficient of the microstrip antenna designed in this invention. The horizontal axis covers 2.0-5.0 GHz, and the vertical axis quantifies the ratio of reflected power to incident power in dB (the larger the absolute negative value, the better the impedance matching). The curve shows two core resonant ranges: the first is 2.45-2.76 GHz (corresponding to the 5G n41 band), where the U-shaped grooves on the outer layer of the radiating patch (deeper, extending the current path) and the L-shaped defective ground structure of the metal ground layer (horizontal / vertical strip grooves are 19 mm long and 12 mm wide, regulating the ground current distribution) work together to achieve the best reflection coefficient |S11| in this frequency band. 11|≤-10dB; the second is 3.22-4.56GHz (corresponding to the n77 / n78 frequency band), which is jointly controlled by the U-shaped groove in the inner layer of the radiation patch (with a shorter depth to compress the current path), the 3.5mm×3.5mm coupling metal patch (which forms capacitive proximity coupling with the feed column with a diameter of 1.27mm and a length of 7.5mm to compensate for the distributed inductance introduced by the aspect ratio of the feed column) and the L-shaped defect ground to achieve |S in this frequency band 11 |≤-10dB. Around 3.64GHz|S 11 The signal level dropped to below -45dB, demonstrating the frequency separation effect of the dual U-slots and the impedance matching optimization capability of the coupled feed, verifying the antenna's broadband matching performance in the 5G Sub-6 core frequency band.

[0057] Figure 10 The 3D total gain pattern of the microstrip antenna designed in this invention adopts a spherical coordinate system (the Z axis is the zenith angle θ direction, and the X and Y axes constitute the azimuth angle The 3D radiation pattern is shown in the XZ plane (Figure 2). The color bar on the left quantifies the gain value in dB. The red area corresponds to high gain (up to 5.714 dB) and the blue area corresponds to low gain (down to -11.46 dB). Since the double U-shaped grooves etched in the radiation patch are symmetrical about the X axis, with the opening along the negative direction of the X axis, and the 3.5mm×3.5mm coupling metal patch is aligned with the edge of the radiation patch, the current distribution in the X direction is more symmetrical. The main lobe is concentrated along the length of the radiating patch and slightly wider in the YZ plane (θ = 90°, along the width of the radiating patch), exhibiting directional radiation characteristics. The low-loss characteristics of the 7.5mm thick first dielectric substrate, the capacitive proximity coupling between the metal feed post and the coupling patch (compensating for distributed inductance to ensure efficient energy transfer), and the L-shaped defect ground structure of the metal ground layer (suppressing reverse current and reducing back radiation) together concentrate the high-gain area (red) in the positive direction of the Z axis and the extension direction of the X axis, verifying the antenna's directional radiation capability and high-gain performance within the operating frequency band (such as 3.22-4.56GHz) (the peak gain is close to the 6.1dBi recorded in the technical briefing, but fluctuates slightly due to differences in specific frequency points).

[0058] Figure 11 The 3D total gain pattern of the microstrip antenna designed in this invention adopts a spherical coordinate system (the Z axis corresponds to the zenith angle θ direction, and the X and Y axes constitute the azimuth angle The color bar on the left quantifies the gain value in dB, with the red area corresponding to high gain (up to 7.186 dB) and the blue area corresponding to low gain (down to -16.229 dB). Because the dual U-shaped slots etched into the radiating patch are symmetrical about the X-axis and open along the negative X-axis, and the 3.5mm×3.5mm coupling metal patch is aligned with the edge of the radiating patch, the X-direction current distribution is more symmetrical. As a result, the high-gain region (red) of the 3D radiation pattern is concentrated in the positive Z-axis and along the X-axis, exhibiting directional radiation characteristics. The 1.27mm diameter, 7.5mm length metal feed post forms capacitive proximity coupling with the coupling patch (compensating for the distributed inductance introduced by the feed post's aspect ratio). This, combined with the low-loss characteristics of the 7.5mm-thick first dielectric substrate, ensures efficient energy transfer. The L-shaped defective ground structure of the metal ground layer (horizontal and vertical slots 19mm long and 12mm wide) suppresses reverse current and reduces back radiation (blue area). Ultimately, the antenna demonstrates directional radiation capability and high gain performance within the operating frequency band (e.g., 3.22-4.56GHz) (peak gain adapts to the frequency band, demonstrating gain stability within the broadband).

[0059] Figure 12 The 3D total gain pattern of the broadband miniaturized microstrip antenna designed in this invention adopts a spherical coordinate system (the Z axis corresponds to the zenith angle θ direction, and the X and Y axes constitute the azimuth angle The color bar on the left quantifies the gain value in dB, with the red area corresponding to high gain (up to 6.541 dB) and the blue area corresponding to low gain (down to -31.614 dB). Because the dual U-shaped slots etched into the radiating patch are symmetrical about the X-axis and open along the negative X-axis, and the 3.5mm×3.5mm coupling metal patch is aligned with the edge of the radiating patch, the X-direction current distribution is more symmetrical. Therefore, the high-gain region (red) of the 3D radiation pattern is concentrated in the positive Z-axis and the X-axis extension direction, exhibiting directional radiation characteristics. The 1.27mm diameter, 7.5mm length metal feed post forms capacitive proximity coupling with the coupling patch (compensating for the distributed inductance introduced by the feed post aspect ratio). Combined with the low-loss characteristics of the 7.5mm thick first dielectric substrate (dielectric constant ≈ 1, loss tangent ≈ 0), this ensures efficient energy transfer. The L-shaped defective ground structure of the metal ground layer (horizontal and vertical strips 19mm long and 12mm wide) modulates the ground current path, suppressing reverse radiation and significantly reducing the gain in the back-facing region (blue). This ultimately verifies that the antenna operates in the operating frequency band (3.22-4.56GHz, covering 5G) n77 / n78, etc.) with directional radiation capability and high gain stability (peak gain adaptation frequency band characteristics, reflecting the synergistic optimization effect of double U-slot and coupled feeding).

[0060] Figure 13The 3D total gain pattern of the microstrip antenna designed in this invention adopts a spherical coordinate system (the Z axis corresponds to the zenith angle θ direction, and the X and Y axes constitute the azimuth angle The spatial radiation characteristics are quantified on the plane, and the color bar on the left shows the gain gradient in dB (the red area corresponds to the highest gain of 5.1112dB, and the blue area corresponds to the lowest gain of -20.015dB). The formation of this radiation pattern is due to the synergy between the multi-layer structure of the antenna and the electromagnetic design: the inner and outer nested double U-shaped grooves (groove width 0.5mm) etched on the surface of the radiation patch (1, 28.5mm×15mm) extend the current path through the meander effect, supporting the dual-band resonance of 2.45GHz-2.76GHz (5Gn41) and 3.22GHz-4.56GHz (n77, n78); the 3.5mm×3.5mm coupling metal patch (3) is 1.6mm vertically spaced from the radiation patch (the thickness of the second dielectric substrate), and uses near-field coupling to transmit energy from the coaxial cable feeding end (through the metal feeding column penetrating the 7.5mm first The L-shaped defective ground structure of the metal ground layer (6) (regulating the distribution of the ground current) and the 7.5 mm thick first dielectric substrate (dielectric constant ≈ 1, low loss) jointly suppress the back radiation (blue area), so that the high gain area (red) is concentrated in the positive direction of the Z axis and the extension direction of the X axis (because the double U-shaped groove is symmetrical about the X axis and the opening is along the negative direction of the X axis, the symmetry of the current in the X direction is enhanced). Finally, the directional radiation capability and gain stability of the antenna in the working frequency band are verified. The peak gain of 5.11 dB is adapted to the signal transmission requirements of the 3.22 GHz-4.56 GHz frequency band.

[0061] The broadband miniaturized microstrip antenna for wireless terminal devices proposed in the present invention has a compact structure, is easy to integrate, has a small size, and is easy to process and manufacture. The feeding structure adopts a coaxial feeding method with spatial coupling feeding, which can reduce the complex feeding circuit design. The use of a first dielectric substrate and a common second dielectric substrate can reduce costs and manufacturing difficulty, facilitating the integrated application of the antenna in various wireless terminal devices. Furthermore, the microstrip antenna proposed in the present invention uses a meandering technique to etch a dual U-shaped groove structure on the radiating metal patch, which can change the effective path length of the current. This ensures the miniaturization of the antenna while also having a wide operating frequency band. It can simultaneously operate in the 2.45GHz-2.76GHz and 3.22GHz-4.56GHz frequency bands, covering the commonly used communication frequency bands in 5G Sub6.

[0062] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of this specification and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units that are inherent to the process, method, product, or apparatus.

[0063] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A broadband miniaturized microstrip antenna for wireless terminal equipment, characterized in that: include: A metal grounding layer (6), the metal grounding layer (6) comprising a grounding plate metal patch, on which an L-shaped defect ground structure is etched, the L-shaped defect ground structure being composed of horizontal strip grooves and vertical strip grooves orthogonally; a first dielectric substrate (5) and a second dielectric substrate (2) are sequentially stacked on the upper surface of the metal grounding layer (6); wherein the dielectric constant of the first dielectric substrate (5) is less than a first predetermined threshold value, the dielectric constant of the second dielectric substrate (2) is greater than a second predetermined threshold value, and the first predetermined threshold value is less than the second predetermined threshold value; A coupling metal patch (3) is provided between the first dielectric substrate (5) and the second dielectric substrate (2); a metal radiation patch (1) is mounted on the upper surface of the second dielectric substrate (2); the metal radiation patch (1) is etched with a double U-shaped groove structure nested inside and outside; A metal feeding column (4) vertically penetrates the first dielectric substrate (5), a first end of the metal feeding column (4) is electrically connected to the coupling metal patch (3), and a second end of the metal feeding column (4) is electrically connected to a feeding port (7) provided on the metal grounding layer (6); a feeding line is provided in the first dielectric substrate (5), and the feeding line is connected to the feeding port (7) via the metal feeding column (4); The coupling metal patch (3) partially overlaps with the metal radiation patch (1) in a vertical direction, so as to achieve coupled power feeding and radiate electromagnetic waves from the metal radiation patch (1).

2. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The inner and outer nested double U-shaped groove structures on the metal radiation patch (1) are symmetrically distributed in the center of the plane, and the opening directions of the two U-shaped grooves are consistent. The inner U-shaped groove and the outer U-shaped groove form a nested gap in the horizontal direction.

3. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The coupling metal patch (3) is arranged on the upper surface of the first dielectric substrate (5) and is attached to the lower surface of the second dielectric substrate (2); the metal radiation patch (1) completely covers the corresponding area of ​​the upper surface of the second dielectric substrate (2); and the overlapping area of ​​the two in the vertical projection direction forms a coupling feeding interval.

4. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The L-shaped defective ground structure on the metal grounding layer (6) is located directly above the feeding port (7), the horizontal strip groove extends along the length direction of the metal grounding layer (6), and the vertical strip groove extends along the width direction of the metal grounding layer (6), and the connection node between the two corresponds to the projection position of the feeding port (7).

5. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The thickness of the second dielectric substrate (2) is less than that of the first dielectric substrate (5), and the two are made of different materials; the thickness of the second dielectric substrate (2) is 1.5mm-1.7mm, and the size is 60mm×60mm-62mm×62mm; the thickness of the first dielectric substrate (5) is 7-8mm, and the size is 60mm×60mm-62mm×62mm; the size of the metal grounding layer (6) is 65mm×65mm-68mm×68mm.

6. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The coupling metal patch (3) is square in shape, has a size of 3.4mm×3.4mm-3.7mm×3.7mm, and the edges of both the metal radiation patch (1) and the coupling metal patch (3) are aligned with the same side of the second dielectric substrate (2).

7. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The size of the metal radiation patch (1) is 28.5 mm×15 mm.

8. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The metal feeding post (4) has a diameter of 1.5 mm to 1.7 mm and a length of 7 mm to 8 mm; the metal feeding post (4) only passes through the first dielectric substrate (5) to connect to the coupling metal patch (3), and does not contact the metal radiation patch (1) or the second dielectric substrate (2).

9. The broadband miniaturized microstrip antenna for wireless terminal equipment according to claim 1, characterized in that: The length and width of the horizontal strip grooves and the vertical strip grooves of the L-shaped defective ground structure are the same, wherein the length is 18mm-20mm and the width is 10mm-14mm.

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