Closely spaced E-plane pattern adjustable MIMO microstrip antenna

Abstract

This invention relates to the field of microstrip antenna technology, and more particularly to a tightly spaced MIMO microstrip antenna with adjustable E-plane radiation pattern. The antenna includes main patch elements, a quarter-wavelength impedance transformation line, a feed transmission line, a dielectric substrate, a metal ground plane, a metal ground wall, and a metal strip. Two main patch elements are located on the upper surface of the dielectric substrate with a spacing of 2.58 mm. This invention places a metal strip with etched bends between the two patch elements arranged in the E-plane. The antenna energy is coupled to the metal strip through near-field coupling and excites the gaps, resulting in a combination of gap radiation energy and antenna radiation energy, which modulates the tilted radiation pattern. This achieves side-firing close to the gap antenna elements. Simultaneously, the metal ground wall below the metal strip extends the ground current path, achieving decoupling. This invention improves the isolation between the two tightly spaced patch elements along the E-plane and enables adjustable unilateral radiation patterns, making it suitable for future small MIMO antennas.

Description

Technical Field

[0001] This invention relates to the field of microstrip antenna technology, and more particularly to a tightly spaced E-plane pattern adjustable MIMO microstrip antenna. Background Art

[0002] The demand for miniaturized multi-antenna structures has made compact antenna element spacing a current research focus. However, this reduction in spacing leads to strong coupling between elements, affecting the antenna's radiation performance. Furthermore, current decoupling techniques often result in antenna pattern tilting, a common phenomenon that restricts directional radiation in the side-firing direction and reduces the flexibility of compact antenna structures. Summary of the Invention

[0003] The purpose of this invention is to provide a tightly spaced E-plane pattern adjustable MIMO microstrip antenna, which aims to achieve decoupling while adjusting the radiation pattern of a single-sided tilted antenna to the side-firing direction and maintaining the tilted radiation characteristics of the other antenna.

[0004] To achieve the above objectives, the present invention provides a closely spaced MIMO microstrip antenna with adjustable E-plane radiation pattern, comprising main patch units, a quarter-wavelength impedance transformation line, a feed transmission line, a dielectric substrate, a metal ground plane, a metal ground wall, and a metal strip. Two main patch units are located on the upper surface of the dielectric substrate with a spacing of 2.58 mm. A quarter-wavelength impedance transformation line is connected to one side of each main patch unit. The outer side of the quarter-wavelength impedance transformation line is connected to the feed transmission line. The two feed transmission lines are respectively located at both ends of the upper surface of the dielectric substrate. The metal ground plane is located on the lower surface of the dielectric substrate. The metal strip is located between the two main patch units and is on the same plane as the two main patch units. The metal ground wall is erected between the two main patch units and located below the metal strip.

[0005] The dielectric substrate is arranged in a rectangular shape that is narrow vertically and long horizontally, and the main patch unit, the 1 / 4 wavelength impedance transformation line and the power supply transmission line are all arranged along the horizontal length of the dielectric substrate.

[0006] The dielectric substrate has a dielectric constant of 4.4, a loss tangent of 0.0033, and a thickness of 1.6 mm.

[0007] The metal floor wall is connected to the metal grounding plate but not to the metal strip.

[0008] One side of the metal strip is etched with a bending gap.

[0009] The length of the bend in the metal strip is equal to half the operating wavelength of the antenna.

[0010] This invention provides a tightly spaced MIMO microstrip antenna with an adjustable E-plane radiation pattern, comprising main patch elements, a 1 / 4 wavelength impedance transformation line, a feed transmission line, a dielectric substrate, a metal ground plane, a metal ground wall, and a metal strip. Two main patch elements are located on the upper surface of the dielectric substrate with a spacing of 2.58 mm. This invention places a metal strip with etched bends between the two patch elements arranged in the E-plane. The antenna energy is coupled to the metal strip through near-field coupling and excites the gaps in the metal strip. The energy radiated from the gaps combines with the energy radiated by the antenna to adjust the tilted radiation pattern, achieving side-firing of the antenna. At the same time, the metal ground wall below the metal strip extends the ground current path to achieve decoupling. This invention improves the isolation between the two patch elements arranged closely along the E-plane (spacing 1 / 20 wavelength) and achieves adjustable single-sided radiation pattern, making it suitable for future small MIMO antennas. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the structure of a tightly spaced E-plane pattern adjustable MIMO microstrip antenna according to the present invention.

[0013] Figure 2 This is a top view of a tightly spaced E-plane pattern adjustable MIMO microstrip antenna according to the present invention.

[0014] Figure 3 This is a schematic diagram of the metal ground wall dimensions of a tightly spaced E-plane pattern adjustable MIMO microstrip antenna according to the present invention.

[0015] Figure 4 This is a schematic diagram of the dimensions of a metal strip with etched and bent slots, which is a tightly spaced MIMO microstrip antenna with adjustable E-plane radiation pattern according to the present invention.

[0016] Figure 5 This is a comparison chart of S-parameters with and without the addition of a decoupling adjustable structure in a specific embodiment of the present invention.

[0017] Figure 6 This is a comparison diagram of the E-plane radiation patterns of a specific embodiment of the present invention with and without the addition of a decoupling adjustable structure.

[0018] 1-Main patch unit, 2-1 / 4 wavelength impedance transformation line, 3-Power supply transmission line, 4-Dielectric substrate, 5-Metal ground plane, 6-Metal ground wall, 7-Metal strip. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] Please see Figure 1 This invention proposes a closely spaced MIMO microstrip antenna with adjustable E-plane radiation pattern, comprising main patch units 1, 1 / 4 wavelength impedance transformation lines 2, feed transmission lines 3, dielectric substrate 4, metal ground plane 5, metal ground wall 6, and metal strip 7. Two main patch units 1 are located on the upper surface of the dielectric substrate 4 with a spacing of 2.58 mm (1 / 20 wavelength). Each main patch unit 1 has a 1 / 4 wavelength impedance transformation line 2 connected to one side. The outer side of each 1 / 4 wavelength impedance transformation line 2 is connected to the feed transmission line 3. The two feed transmission lines 3 are located at opposite ends of the upper surface of the dielectric substrate 4. The metal ground plane 5 is located on the lower surface of the dielectric substrate 4. The metal strip 7 is located between the two main patch units 1 and is on the same plane as the two main patch units 1. The metal ground wall 6 is erected between the two main patch units 1 and located below the metal strip 7.

[0021] The dielectric substrate 4 is arranged in a rectangular shape that is narrow vertically and long horizontally. The main patch unit 1, the 1 / 4 wavelength impedance transformation line 2 and the power supply transmission line 3 are all arranged along the horizontal length of the dielectric substrate 4.

[0022] The dielectric substrate 4 has a dielectric constant of 4.4, a loss tangent of 0.0033, and a thickness of 1.6 mm.

[0023] The metal floor wall 6 is connected to the metal floor plate 5 but not to the metal strip 7.

[0024] One side of the metal strip 7 is etched with a bending gap.

[0025] The length of the bend in the metal strip 7 is equal to half the operating wavelength of the antenna.

[0026] The following description, in conjunction with specific embodiments, provides further details. Please refer to the provided text. Figures 2 to 6 :

[0027] In this embodiment, the bending gap is etched on the left side of the metal strip 7, while the bending gap is not etched on the right side of the metal strip 7. The main patch unit 1 is fed by the power supply transmission line 3.

[0028] The main patch unit 1 has a length L1 = 11.1 mm and a width W1 = 16 mm.

[0029] The 1 / 4 impedance transformation line 2 has a length L2 = 7.4 mm and a width W2 = 0.4 mm.

[0030] The power supply transmission line 3 for powering the main surface mount unit has a length L3 = 3mm and a width W3 = 3mm.

[0031] The dielectric substrate 4 has a length L0 = 45.58 mm, a width W0 = 27.4 mm, and a relatively thin thickness of only 1.6 mm.

[0032] Please see Figure 3 , Figure 3 This is a dimensional diagram of the metal ground wall 6 used in the tightly spaced E-plane pattern-adjustable MIMO microstrip antenna of the present invention. The height of the metal ground wall is h. wall =1.4mm, width W wall =16mm, the height of the metal ground wall 6 is less than the height of the dielectric substrate 4, and the width of the metal ground wall 6 is equal to the width of the main patch unit 1.

[0033] Please see Figure 4 , Figure 4 This is a detailed view of the metal strip 7 of the tightly spaced E-plane pattern-adjustable MIMO microstrip antenna described in this invention. The metal strip 7 has a length S. L =2.2mm, width S W =16mm, the first segment of the etched seam has a length of W4=4.6mm, the second segment has a length of W5=1.6mm, and the third segment has a length of W6=3mm. The folded seam has a symmetrical structure, and the interval between each segment is L4=L5=mm.

[0034] Furthermore, the present invention also provides a performance comparison of microstrip antennas with and without a decoupling tunable structure.

[0035] Please see Figure 5 , Figure 5 This is a comparison of the S-parameters of the tightly spaced E-plane pattern-tunable MIMO microstrip antenna described in this invention, with and without the addition of a decoupling controllable structure. The solid lines represent the S11 and S21 curves with and without the decoupling controllable structure, while the dashed lines represent the S11 and S21 curves without the decoupling controllable structure. Figure 5A comparison of the solid and dashed lines shows that after adding the metal ground wall 6 and the metal strip 7, the center frequency did not shift, the matching characteristics decreased slightly, but the coupling at the center frequency also decreased from -11dB to -16.4dB, achieving an isolation improvement of 5.4dB.

[0036] Please see Figure 6 , Figure 6 This is a comparison of the E-plane radiation patterns of the tightly spaced, tunable E-plane microstrip antenna described in this invention, with and without a decoupling controllable structure. The solid line represents the E-plane radiation pattern with the decoupling controllable structure, and the dashed line represents the E-plane radiation pattern without the decoupling controllable structure (which also points to the other side of the tunable antenna pattern). Figure 6 A comparison of the solid and dashed lines shows that after adding the decoupling adjustable structure, the maximum pointing of the antenna's E-plane radiation pattern is adjusted from 32° to 0°, and the radiation pattern points to the side-firing direction of the antenna, thus realizing the control of the single-sided radiation pattern.

[0037] In summary, the decoupling and pattern controllability of this invention are achieved by placing a metal strip with etched bends between two patch antennas arranged in the E-plane. The antenna energy is coupled to the metal strip through near-field coupling and excites the gaps in the metal strip. The energy radiated from the gaps combines with the energy radiated from the antenna to form an energy direction pointing towards the main radiation direction of the antenna, thereby controlling the tilted radiation pattern. The metal ground wall below the etched bends in the metal strip extends the ground current path, achieving the decoupling effect. This invention can improve the isolation between two patch antennas arranged closely along the E-plane (spacing 1 / 20 wavelength) and achieve unilateral radiation pattern controllability, which is beneficial for the future arraying of small antenna arrays.

[0038] The above description discloses only one or more preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A MIMO microstrip antenna with tunable E-plane radiation pattern and close spacing, characterized in that, The device includes main patch units, a quarter-wavelength impedance transformation line, a power supply transmission line, a dielectric substrate, a metal ground plane, a metal ground wall, and a metal strip. Two main patch units are located on the upper surface of the dielectric substrate with a spacing of 2.58 mm. Each main patch unit has a quarter-wavelength impedance transformation line connected to one side. The outer side of the quarter-wavelength impedance transformation line is connected to the power supply transmission line. Two power supply transmission lines are located at opposite ends of the upper surface of the dielectric substrate. The metal ground plane is located on the lower surface of the dielectric substrate. The metal strip is located between the two main patch units and is on the same plane as the two main patch units. The metal ground wall is erected between the two main patch units and located below the metal strip. The metal floor wall is connected to the metal grounding plate but not to the metal strip; One side of the metal strip is etched with a bending slot; The length of the bend in the metal strip is equal to half the equivalent wavelength of the antenna.

2. The tightly spaced E-plane pattern-tunable MIMO microstrip antenna as described in claim 1, characterized in that, The dielectric substrate is arranged in a rectangular shape that is narrow vertically and long horizontally. The main patch unit, the 1 / 4 wavelength impedance transformation line and the power supply transmission line are all arranged along the horizontal length of the dielectric substrate.

3. The tightly spaced E-plane pattern-tunable MIMO microstrip antenna as described in claim 2, characterized in that, The dielectric substrate has a dielectric constant of 4.4, a loss tangent of 0.0033, and a thickness of 1.6 mm.

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