Tightly-spaced MIMO microstrip antenna with adjustable E-plane directional diagram

Abstract

The invention relates to the technical field of microstrip antennas, in particular to a tight-interval E-plane directional diagram adjustable MIMO microstrip antenna which comprises main patch units, a 1 / 4 wavelength impedance conversion line, a feed transmission line, a dielectric substrate, a metal grounding plate, a metal ground wall and a metal strip, the two main patch units are located on the upper surface of the dielectric substrate, and the interval between the two main patch units is 2.58 mm; according to the invention, the metal strip etched with the bent gap is placed between the two patch units arranged on the E surface, the energy of the antenna is coupled to the metal strip through a near field and excites the gap, the energy radiated by the gap is combined with the energy radiated by the antenna, an inclined directional diagram is regulated and controlled, and edge emission close to the gap antenna unit is realized; and meanwhile, the metal ground wall below the metal strip plays a role in prolonging a ground current path to achieve a decoupling effect, so that the isolation degree between the two patch units which are closely arranged along the E surface is improved, a single-side radiation pattern can be regulated and controlled, and the antenna is suitable for a future small MIMO (Multiple Input Multiple Output) antenna.

Description

Technical Field

[0001] The present invention relates to the technical field of microstrip antennas, and in particular to a MIMO microstrip antenna with closely spaced E-plane directional patterns that can be adjusted. Background Art

[0002] The development demand for miniaturized multi-antenna structures has made the compact arrangement of antenna units with reduced spacing between them a current research focus. However, the corresponding reduction in spacing will cause strong coupling between units, which in turn affects the radiation performance of the antenna. However, the current decoupling technology is usually accompanied by a tilt in the antenna pattern. This common phenomenon restricts the directional radiation of the antenna in the side-firing direction and reduces the flexibility of the compact antenna structure. Summary of the invention

[0003] The object of the present invention is to provide a MIMO microstrip antenna with closely spaced E-plane directional patterns that can be adjusted, so as to achieve decoupling while making the unilateral tilted radiation pattern adjustable to the side-firing direction and maintaining the tilted radiation characteristics of the other antenna.

[0004] To achieve the above-mentioned purpose, the present invention provides a MIMO microstrip antenna with a tight spacing and adjustable E-plane radiation pattern, comprising a main patch unit, a 1 / 4 wavelength impedance transformation line, a feeding transmission line, a dielectric substrate, a metal ground plate, a metal ground wall and a metal strip, wherein two main patch units are located on the upper surface of the dielectric substrate and are spaced 2.58 mm apart, one side of each main patch unit is respectively connected to a 1 / 4 wavelength impedance transformation line, the outer side of the 1 / 4 wavelength impedance transformation line is connected to the feeding transmission line, the two feeding transmission lines are respectively arranged at two ends of the upper surface of the dielectric substrate, the metal ground plate is located on the lower surface of the dielectric substrate, the metal strip is located between the two main patch units and is in the same plane as the two main patch units, and the metal ground wall is erected between the two main patch units and is 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 feeding transmission line are all arranged along the horizontal length of the dielectric substrate.

[0006] The dielectric constant of the dielectric substrate is 4.4, the loss tangent value is 0.0033, and the thickness is 1.6 mm.

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

[0008] Wherein, a bending gap is etched on one side of the metal strip.

[0009] The length of the bending gap on the metal strip is equal to half the antenna working wavelength.

[0010] The present invention provides a MIMO microstrip antenna with closely spaced E-plane directional patterns that can be adjusted. The antenna comprises a main patch unit, a 1 / 4 wavelength impedance transformation line, a feeding transmission line, a dielectric substrate, a metal ground plate, 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. The present invention places a metal strip with a bent gap etched therein between two patch units arranged on the E-plane. The energy of the antenna is coupled to the metal strip through the near field and stimulates the gap on the metal strip. The energy radiated by the gap is combined with the energy radiated by the antenna to adjust the inclined directional pattern, thereby realizing the side emission of the antenna. At the same time, the metal ground wall below the metal strip serves to extend the ground current path to achieve the effect of decoupling. The present invention not only improves the isolation between two patch units closely arranged along the E-plane (with a spacing of 1 / 20 wavelength), but also realizes the adjustable unilateral radiation pattern. The antenna is suitable for future small MIMO antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0012] Figure 1 It is a structural schematic diagram of a MIMO microstrip antenna with closely spaced E-plane directional patterns that can be adjusted according to the present invention.

[0013] Figure 2 It is a top view of a MIMO microstrip antenna with closely spaced E-plane radiation pattern and controllable characteristics according to the present invention.

[0014] Figure 3 It is a schematic diagram of the dimensions of a metal ground wall of a MIMO microstrip antenna with closely spaced E-plane radiation patterns and controllable characteristics according to the present invention.

[0015] Figure 4 It is a schematic diagram of the dimensions of a metal strip with etched bent gaps of a MIMO microstrip antenna with a tight spacing and adjustable E-plane radiation pattern according to the present invention.

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

[0017] Figure 6 It is a comparison diagram of the E-plane directional diagrams with and without the decoupling adjustable structure in a specific embodiment of the present invention.

[0018] 1-main patch unit, 2-1 / 4 wavelength impedance transformation line, 3-feeding transmission line, 4-dielectric substrate, 5-metal ground plane, 6-metal ground wall, 7-metal strip. DETAILED DESCRIPTION

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

[0020] See also Figure 1 The present invention proposes a MIMO microstrip antenna with a tight spacing and adjustable E-plane radiation pattern, comprising a main patch unit 1, a 1 / 4 wavelength impedance transformation line 2, a feeding transmission line 3, a dielectric substrate 4, a metal ground plate 5, a metal ground wall 6 and a metal strip 7, wherein the two main patch units 1 are located on the upper surface of the dielectric substrate 4 and are spaced 2.58 mm (1 / 20 wavelength) apart, one side of each main patch unit 1 is connected to a 1 / 4 wavelength impedance transformation line 2, the outer side of the 1 / 4 wavelength impedance transformation line 2 is connected to the feeding transmission line 3, the two feeding transmission lines 3 are arranged at both ends of the upper surface of the dielectric substrate 4, the metal ground plate 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 in the same plane as the two main patch units 1, and the metal ground wall 6 is erected between the two main patch units 1 and is 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 feeding 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 ground wall 6 is connected to the metal ground plate 5 but is not connected to the metal strip 7 .

[0024] A bending gap is etched on one side of the metal strip 7 .

[0025] The length of the bending gap on the metal strip 7 is equal to half the antenna working wavelength.

[0026] The following is further described in conjunction with specific embodiments. Figures 2 to 6 :

[0027] In this embodiment, a bending slot is etched on the left side of the metal strip 7 with the bending slot, and no bending slot is etched on the right side of the metal strip 7 , and the main patch unit 1 is fed by the feeding 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 feeding transmission line 3 for feeding the main patch unit has a length L3 = 3 mm and a width W3 = 3 mm.

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

[0032] See also Figure 3 , Figure 3 The dimensions of the metal ground wall 6 used in the MIMO microstrip antenna with closely spaced E-plane directional pattern controllable according to the present invention are shown in FIG. 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] See also Figure 4 , Figure 4 This is a detailed view of the metal strip 7 of the MIMO microstrip antenna with closely spaced E-plane directional pattern controllable according to the present invention. The metal strip 7 has a length S L =2.2mm, width S W =16mm, the length of the first section of the slit etched thereon is W4=4.6mm, the length of the second section is W5=1.6mm, the length of the third section is W6=3mm, the bending slit is a symmetrical structure, and the interval between each section is L4=L5=mm.

[0034] Furthermore, the present invention also compares the performance of a microstrip antenna with a decoupling adjustable structure and a microstrip antenna without a decoupling adjustable structure.

[0035] See also Figure 5 , Figure 5 This is a comparison of the S parameters of the tightly spaced E-plane directional pattern adjustable MIMO microstrip antenna of the present invention, with and without the decoupling adjustable structure. The solid line represents the S11 and S21 curves with and without the decoupling adjustable structure, and the dotted line represents the S11 and S21 curves without the decoupling adjustable structure. Figure 5By comparing the solid line with the dotted line, it can be seen that after adding the metal ground wall 6 and the metal strip 7, the center frequency point does not shift, and the matching characteristics are slightly reduced, but the coupling degree at the center frequency point is also reduced from the original -11dB to -16.4dB, achieving an isolation improvement of 5.4dB.

[0036] See also Figure 6 , Figure 6 This is a comparison diagram of the E-plane radiation pattern of the tightly spaced MIMO microstrip antenna with adjustable E-plane radiation pattern as described in the present invention, with and without the addition of a decoupling adjustable structure. The solid line represents the E-plane radiation pattern with the addition of the decoupling adjustable structure, and the dotted line represents the E-plane radiation pattern without the addition of the decoupling adjustable structure (which is also the direction of the adjustable antenna radiation pattern on the other side). Figure 6 By comparing the solid line and the dotted line, it can be seen that after adding the decoupling adjustable structure, the maximum direction of the antenna E-plane radiation pattern is adjusted from 32° to 0°, and the radiation pattern points to the side-firing direction of the antenna, realizing the control of the unilateral radiation pattern.

[0037] In summary, the decoupling and controllable radiation pattern of the present invention is achieved by placing a metal strip etched with a bent gap between two patch antennas arranged on the E plane. The energy of the antenna is coupled to the metal strip through the near field and excites the gap on the metal strip. The energy radiated by the gap is combined with the energy radiated by the antenna to form an energy pointing in the main radiation direction of the antenna, thereby controlling the inclined radiation pattern. The metal ground wall below the metal strip etched with the bent gap serves to extend the ground current path to achieve the effect of decoupling. The present invention can improve the isolation between two patch antennas that are closely arranged along the E plane (spacing 1 / 20 wavelength), and realize the controllable unilateral radiation pattern, which is conducive to the formation of small antenna arrays in the future.

[0038] What is disclosed above is only one or more preferred embodiments of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of implementing the above embodiments and making equivalent changes according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A MIMO microstrip antenna with closely spaced E-plane radiation pattern and adjustable radiation pattern, characterized in that: The invention comprises a main patch unit, a 1 / 4 wavelength impedance transformation line, a feeding transmission line, a dielectric substrate, a metal ground plate, a metal ground wall and a metal strip. The two main patch units are located on the upper surface of the dielectric substrate and are spaced 2.58 mm apart. One side of each main patch unit is respectively connected to a 1 / 4 wavelength impedance transformation line, and the outer side of the 1 / 4 wavelength impedance transformation line is connected to the feeding transmission line. The two feeding transmission lines are arranged at two ends of the upper surface of the dielectric substrate. The metal ground plate is located on the lower surface of the dielectric substrate. The metal strip is located between the two main patch units and is in the same plane as the two main patch units. The metal ground wall stands between the two main patch units and is located below the metal strip.

2. The closely spaced E-plane directional pattern controllable MIMO microstrip antenna according to claim 1, characterized in that: The dielectric substrate is arranged in a rectangular shape that is vertically narrow and laterally long, and the main patch unit, the 1 / 4 wavelength impedance transformation line and the feeding transmission line are all arranged along the lateral length of the dielectric substrate.

3. The closely spaced E-plane directional pattern controllable MIMO microstrip antenna according to claim 2, characterized in that: The dielectric constant of the dielectric substrate is 4.4, the loss tangent value is 0.0033, and the thickness is 1.6 mm.

4. The MIMO microstrip antenna with closely spaced E-plane radiation pattern controllable as claimed in claim 3, characterized in that: The metal ground wall is connected to the metal ground plate but not to the metal strip.

5. The closely spaced E-plane directional pattern controllable MIMO microstrip antenna according to claim 4, characterized in that: A bending gap is etched on one side of the metal strip.

6. The closely spaced E-plane directional pattern controllable MIMO microstrip antenna according to claim 5, characterized in that: The length of the bending gap on the metal strip is equal to half the antenna equivalent wavelength.

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