Broadband self-decoupling laminated microstrip patch antenna pair arranged at close interval

Abstract

The invention discloses a close-spaced broadband self-decoupling laminated microstrip patch antenna pair, which is of a layered structure and comprises a first dielectric substrate and a second dielectric substrate which are arranged in parallel, an air layer exists between the first dielectric substrate and the second dielectric substrate, a parasitic metal patch is arranged on the upper surface of the first dielectric substrate, and the parasitic metal patch is arranged on the lower surface of the second dielectric substrate. An extremely thin metal coupling line is embedded between two adjacent parasitic metal patches, and a gap with a fixed width exists at the internal intersection part of the metal coupling line and the parasitic metal patches; a driving metal patch is arranged on the upper surface of the second dielectric substrate, and a metal ground is arranged on the lower surface of the second dielectric substrate. The self-decoupling laminated microstrip patch antenna pair is realized under the condition of no additional structure or circuit under the condition that the antenna units are arranged at close intervals, and the self-decoupling laminated microstrip patch antenna pair has the characteristics of simple structure, broadband self-decoupling, wide impedance bandwidth, high total radiation efficiency, high visual axis gain, easiness in integration and the like.

Description

Technical Field

[0001] The present invention relates to a pair of closely spaced broadband self-decoupling stacked microstrip patch antennas, belonging to the technical field of antennas in radio equipment. Background Art

[0002] Stacked microstrip patch antennas (S-MPAs) have become a latest effective antenna solution suitable for MIMO scenarios due to their wide bandwidth, wide beam radiation, low manufacturing cost, easy integration, simple structure, and easy implementation of electrostatic discharge (ESD) protection, etc., and play an important role in fields such as fiber to the home (FTTR) applications, panel-type optical network terminals (ONTs), smartphone antenna designs, industrial Internet of Things (IIoT), intelligent transportation systems, small cells, indoor wireless coverage (Indoor DAS), etc.

[0003] However, for conventional multi-element stacked patch antenna arrays, the mutual coupling between elements cannot meet the requirements of modern communications. At the same time, due to the spatial limitations of communication devices, there is a need for closer spacing of antenna elements, and this close-spacing arrangement makes the mutual coupling problem more serious, which is prone to cause problems such as radiation pattern distortion, boresight gain reduction, total radiation efficiency reduction, active matching deterioration, and channel capacity deterioration. Compared with single-layer microstrip antennas, stacked microstrip patch antennas can meet a wider operating bandwidth, but due to more radiation sources affecting mutual coupling, the demand for the decoupling bandwidth of the antenna array also increases accordingly.

[0004] There are mainly 4 existing decoupling techniques available for stacked patch antennas. The first one is to achieve a mutual coupling null by increasing the dielectric constant of the upper substrate, so as to realize an out-of-phase current distribution between the parasitic patch and the driven patch within the target frequency band. However, this technique will weaken the antenna boresight gain and total radiation efficiency to a certain extent. And it shows a relatively weak decoupling effect in the low-frequency part of the interested frequency band. Most importantly, the selection requirements for the substrate are relatively harsh in practical applications, increasing the manufacturing cost. The second one is to use a half-wavelength strip and a double-hole single-pad structure to achieve decoupling. Such solutions that additionally introduce periodic decoupling structures or circuits have problems of complex structure and too large size. The third one is to introduce an artificial surface plasmon polariton (SSPP)-type defected ground structure (DGS). Such a method will increase the back lobe of the radiation pattern (especially the E-plane radiation pattern) and reduce the total radiation efficiency. The fourth one is to suppress mutual coupling by using shorting pins. However, it divides the driven patch into two regions, generating opposite currents at the resonance point, which has an adverse effect on the boresight gain and radiation efficiency.

[0005] Generally speaking, the existing decoupling schemes for stacked patch antennas mainly aim to solve the weak mutual coupling when the patch units are spaced at about half-wavelength intervals. The underlying principle is to utilize the reverse TM 10 mode cancellation of the parasitic radiation patch and the driven radiation patch to counteract the mutual coupling effect on the load. And there are generally problems such as the need to add additional decoupling structures or circuits, which affect the boresight gain and the total radiation efficiency. The related research on strongly suppressing the mutual coupling of stacked patch antennas with closely spaced arrangements is currently in a blank stage. Therefore, it is necessary to invent a broadband self-decoupling scheme with a simple structure for application in stacked microstrip patch antenna arrays with closely spaced arrangements. Summary of the Invention

[0006] Technical Problem: The purpose of the present invention is to provide a pair of broadband self-decoupling stacked microstrip patch antennas with closely spaced arrangements to solve the above-mentioned technical problems existing in the related prior art.

[0007] Technical Solution: A pair of broadband self-decoupling stacked microstrip patch antennas with closely spaced arrangements according to the present invention is a layered structure, including a first dielectric substrate and a second dielectric substrate arranged in parallel. There is an air layer between the first dielectric substrate and the second dielectric substrate. Two parasitic metal patches are provided on the upper surface of the first dielectric substrate, and metal coupling lines are embedded in two adjacent parasitic metal patches. There is a gap with a fixed width at the intersection part of the metal coupling line and the interior of the parasitic metal patch; two adjacent driven metal patches are provided on the upper surface of the second dielectric substrate, and metal probes are respectively connected below the two driven metal patches and are symmetrically distributed; a metal ground is provided on the lower surface of the second dielectric substrate, and the metal probes pass through the second dielectric substrate and the metal ground to connect to the outside.

[0008] The spacing between the adjacent driven metal patches is 0.036λ c ; λ c is the free-space wavelength at the center frequency of the antenna.

[0009] The spacing between the adjacent parasitic metal patches is 0.053λ c ,λ c is the free-space wavelength at the center frequency of the antenna.

[0010] The thickness of the first dielectric substrate is 0.018λ c ,the thickness of the second dielectric substrate is 0.036λ c ,and the thickness of the air layer added between the first dielectric substrate and the second dielectric substrate is 0.05λ c ,λ c is the free-space wavelength at the center frequency of the antenna.

[0011] The side length of the parasitic metal patch is between 0.30λ c -0.33λc A square metal patch between them, the driving metal patch having a side length between 0.33λ c -0.35λ c A square metal patch between them, λ c is the free space wavelength at the center frequency of the antenna.

[0012] The length of the metal coupling line embedded between two adjacent parasitic metal patches is between 0.38λ c -0.42λ c between, and the width is between 0.0012λ c -0.0072λ c between.

[0013] The metal coupling line is embedded on two adjacent parasitic metal patches, and there is a gap with a fixed width in the embedded part, which is 0.0012λ c -0.0036λ c , λ c is the free space wavelength at the center frequency of the antenna.

[0014] The driving metal patches are arranged along the direction of the electric field plane.

[0015] The material of the first dielectric substrate is a glass cloth-reinforced hydrocarbon and ceramic composite material, and the material of the second dielectric substrate is polytetrafluoroethylene or epoxy resin.

[0016] Advantages: In the present invention, an extremely thin metal coupling line is embedded between two adjacent parasitic metal patches of a stacked microstrip patch antenna array arranged in a close pitch to form an antenna pair, and a gap with a fixed width is provided at the intersection part inside the metal coupling line and the parasitic metal patch. This broadband self-decoupling technology for stacked patch antennas has six major advantages: 1) It reduces the surface current intensity of the parasitic patches in the load part and reduces the influence of indirect coupling on the load. 2) The surface current distribution of the metal coupling line is opposite to that of the driving patch, achieving the purpose of canceling the coupling paths of both to the load. 3) Since the metal coupling line and the corresponding gap are thin enough, they do not act as effective wide-side radiation elements, but only play a role in coupling adjustment, and do not affect the effective wide-side radiation of the driving patch and the parasitic patch corresponding to the excited antenna element in the fundamental mode TM 10 mode. 4) It realizes the cooperative work of the parasitic radiation patch and the driving patch (the surface currents are distributed in the same direction), greatly improves the boresight gain and total radiation efficiency of the antenna element, and at the same time maintains a relatively wide impedance bandwidth. There is no risk of affecting the wide-side radiation of the antenna and generating radiation nulls caused by the opposite current distribution existing in the existing stacked patch antenna decoupling technology. 5) The antenna pair has a simple structure and is compact, and can achieve self-decoupling without the need to add additional decoupling structures or circuits. 6) It can achieve self-decoupling of different frequencies in adjacent frequency bands. Brief Description of the Drawings

[0017] Figure 1 FIG. 4 is a side cross-sectional structure diagram of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention;

[0018] Figure 2 FIG. 5 is a top view of the front side of the first dielectric substrate of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention;

[0019] Figure 3 FIG. 6 is Detail A of the top view of the front side of the first dielectric substrate of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention;

[0020] Figure 4 FIG. 7 is Detail B of the top view of the front side of the first dielectric substrate of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention

[0021] Figure 5 FIG. 8 is a top view of the front side of the second dielectric substrate of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention;

[0022] Figure 6 FIG. 9 is a comparison diagram of the S-parameter effects of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention, where Figure 6 (a) in FIG. 9 is an embodiment, Figure 6 (b) in FIG. 9 is a stacked microstrip patch antenna pair with a conventional close spacing arrangement;

[0023] Figure 7 FIG. 10 is a comparison diagram of the surface current distributions of the driving layer and the parasitic layer of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention at the center frequency point of 3.6 GHz in the 5G New Radio N77 band (3.3 GHz - 3.8 GHz), where Figure 7 (a) in FIG. 10 is an embodiment, Figure 7 (b) in FIG. 10 is a stacked microstrip patch antenna pair with a conventional close spacing arrangement;

[0024] Figure 8 FIG. 11 is a comparison diagram of the boresight gain of a 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely spaced along the electric field direction plane according to an embodiment of the present invention, where Figure 8 (a) in FIG. 11 is an embodiment, Figure 8 (b) in FIG. 11 is a stacked microstrip patch antenna pair with a conventional close spacing arrangement;

[0025] Figure 9 The comparative diagram of the total radiation efficiency of the 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely arranged along the electric field direction plane according to the embodiment of the present invention, where Figure 9 (a) in it is the embodiment, Figure 9 (b) in it is the stacked microstrip patch antenna pair arranged in a conventional close spacing;

[0026] Figure 10 The radiation pattern of the 1×2 broadband self-decoupling stacked microstrip patch antenna pair closely arranged along the electric field direction plane according to the embodiment of the present invention at the center frequency point of 3.6 GHz in the 5G New Radio N77 band (3.3 GHz - 3.8 GHz). Where Figure 10 (a) in it is the E-plane radiation pattern of the embodiment with port one fed and port two connected to a 50Ω load; where Figure 10 (b) in it is the H-plane radiation pattern of the embodiment with port one fed and port two connected to a 50Ω load; where Figure 10 (c) in it is the E-plane radiation pattern of the stacked microstrip patch antenna pair arranged in a conventional close spacing with port one fed and port two connected to a 50Ω load; Figure 10 (d) in it is the H-plane radiation pattern of the stacked microstrip patch antenna pair arranged in a conventional close spacing with port one fed and port two connected to a 50Ω load;

[0027] Figure 11 The comparative diagram of the S-parameter effect of the 1×2 different-frequency broadband self-decoupling stacked microstrip patch antenna pair closely arranged along the electric field direction plane according to the embodiment of the present invention (taking the 5G New Radio N77 band and N78 band as examples respectively), where Figure 11 (a) in it is the embodiment, Figure 11 (b) in it is the stacked microstrip patch antenna pair arranged in a conventional close spacing;

[0028] In the figure: parasitic metal patch 1, metal coupling line 2, gap 3, first dielectric substrate 4, air layer 5, driving metal patch 6, second dielectric substrate 7, metal ground 8, metal probe 9. Detailed implementation manner

[0029] The present invention will be specifically described below through embodiments. It is necessary to point out here that these embodiments are only used to further illustrate the invention and cannot be understood as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above content of the present invention.

[0030] The antenna is a layered structure, including a first dielectric substrate 4 and a second dielectric substrate 7 arranged in parallel. There is an air layer 5 between the first dielectric substrate 4 and the second dielectric substrate 7. A parasitic metal patch 1 is provided on the upper surface of the first dielectric substrate 4. Ultra-thin metal coupling wires 2 are embedded in two adjacent parasitic metal patches 1. There is a gap 3 with a fixed width at the intersection of the metal coupling wire 2 and the interior of the parasitic metal patch 1. A driving metal patch 6 is provided on the upper surface of the second dielectric substrate 7. The metal probes 9 of the two driving metal patches 6 are symmetrically distributed. A metal ground 8 is provided on the lower surface of the second dielectric substrate 7. The driving metal patch 6 is connected to the metal probe 9, and the metal probe 9 passes through the second dielectric substrate 7 and the metal ground 8 to connect to the outside. Example:

[0031] The overall structure of the broadband self-decoupling stacked microstrip patch antenna pair with closely spaced arrangement of the present invention is as Figures 1 to 5 shown. The broadband self-decoupling stacked microstrip patch antenna pair with closely spaced arrangement is composed of a parasitic layer, an air layer, and a driving layer. The driving patches are arranged along the electric field direction plane, and there is no electrical connection between the parasitic layer and the driving layer. It includes a driving metal patch 1, a metal coupling wire 2, a gap 3, a first dielectric substrate 4, an air layer 5, a driving metal patch 6, a second dielectric substrate 7, a metal ground 8, and a metal probe 9.

[0032] Through simulation calculations, the broadband self-decoupling stacked microstrip patch antenna pair in this example can operate normally in the 5G New Radio N77 band (3.3 GHz - 3.8 GHz), and the self-decoupling effect fully covers the N77 band. The final mutual coupling level of the antenna pair is below -20 dB, reaching the industrial application level of the closely spaced patch antenna array in fields such as fiber to the home (FTTR) applications, panel-type optical network terminals (ONTs), and industrial Internet of Things (IIoT). This example also reduces the surface current intensity of the parasitic patch corresponding to the load part and the surface current intensity of the driving patch of the load part, achieving a real improvement in antenna isolation. Compared with other mode cancellation self-decoupling schemes, there are no strict requirements for the position of the feeding probe in this example.

[0033] The surface current distribution of the metal coupling wire and the driving patch in this example is opposite, achieving the purpose of canceling the coupling paths of the two to the load. At the same time, since the metal coupling wire and the corresponding gap are thin enough, they do not act as effective wide-side radiation elements, but only play a role in coupling adjustment, and will not affect the driving patch and the parasitic patch corresponding to the excited antenna unit in the fundamental mode TM 10Effective broadside radiation in the mode. The parasitic radiation patch works in cooperation with the driven patch (the surface currents are distributed in the same direction), and the boresight gain is increased by more than 1.28 dBi in the N77 band compared with the conventional form, with the highest increase of 3.83 dBi, reaching an average of 6.93 dBi. The total radiation efficiency is increased by 14.8% in the N77 band compared with the conventional form, with an average increase of 20.62%, reaching an average of 90.59%.

[0034] In this example, the cross-frequency self-decoupling of adjacent frequency bands 5G New Radio N77 band (3.3 GHz - 3.8 GHz) and N78 band (3.3 GHz - 4.2 GHz) is also achieved. Within 3.3 GHz - 4.2 GHz, the isolation between the antennas is guaranteed to be greater than 20 dB when arranged in a close spacing, and the isolation reaches 43.83 dB at 3.8 GHz.

Claims

1. A broadband self-decoupling laminated microstrip patch antenna pair arranged in close spacing, characterized in that: The antenna pair is a layered structure, comprising a first dielectric substrate (4) and a second dielectric substrate (7) arranged in parallel, an air layer (5) existing between the first dielectric substrate (4) and the second dielectric substrate (7), two parasitic metal patches (1) being provided on the upper surface of the first dielectric substrate (4), metal coupling lines (2) being embedded in the two adjacent parasitic metal patches (1), and a gap (3) of fixed width existing between the metal coupling lines (2) and the inner intersection of the parasitic metal patches (1); two adjacent driving metal patches (6) being provided on the upper surface of the second dielectric substrate (7), metal probes (9) being connected to the lower parts of the two driving metal patches (6) respectively and being symmetrically distributed; a metal ground (8) being provided on the lower surface of the second dielectric substrate (7), and the metal probes (9) passing through the second dielectric substrate (7) and the metal ground (8) to be connected to the outside.

2. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The spacing between adjacent driving metal patches (6) is 0.036λ c ; c is the free space wavelength at the antenna center frequency.

3. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The spacing between adjacent parasitic metal patches (1) is 0.053λ c ,λ c is the free space wavelength at the antenna center frequency.

4. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The thickness of the first dielectric substrate (4) is 0.018λ c , the thickness of the second dielectric substrate (7) is 0.036λ c The thickness of the air layer (5) added between the first dielectric substrate (4) and the second dielectric substrate (7) is 0.05λ c ,λ c is the free space wavelength at the antenna center frequency.

5. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The parasitic metal patch (1) has a side length of 0.30λ c -0.33λ c The driving metal patch (6) is a square metal patch with a side length of 0.33λ c -0.35λ c The square metal patch between c is the free space wavelength at the antenna center frequency.

6. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The length of the metal coupling line (2) embedded between the two adjacent parasitic metal patches (1) is 0.38λ c -0.42λ c The width is between 0.0012λ c -0.0072λ c between.

7. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The metal coupling line (2) is embedded in two adjacent parasitic metal patches (1), and a gap (3) with a fixed width of 0.0012λ exists in the embedded part. c -0.0036λ c ,λ c is the free space wavelength at the antenna center frequency.

8. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The driving metal patches (6) are arranged along the electric field direction.

9. The broadband self-decoupling laminated microstrip patch antenna pair arranged closely together as claimed in claim 1, characterized in that: The material of the first dielectric substrate (4) is a glass cloth reinforced hydrocarbon and ceramic composite material, and the material of the second dielectric substrate (7) is polytetrafluoroethylene or epoxy resin.

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