Dual-frequency MIMO mutual coupling removal patch antenna based on rectangular groove

Abstract

The invention discloses a dual-frequency MIMO mutual coupling removal patch antenna based on a rectangular groove, and belongs to the technical field of antennas for wireless communication. The antenna comprises a 1 * 2 symmetrical antenna unit array which is composed of a top metal layer, a dielectric substrate, a bottom metal layer and a coaxial probe in sequence. Double-frequency rectangular grooves are etched in the upper edges and the lower edges of the two side-by-side rectangular metal patches on the top layer, decoupling rectangular grooves are formed in the two sides of the upper portions of the rectangular metal patches, the decoupling rectangular grooves are formed between the double-frequency rectangular grooves and the feed port, and the coaxial probe penetrates through the substrate and is connected with the patches to form the feed port. Dual-band resonance is achieved through the dual-band rectangular groove, a weak field area is synchronously formed in dual bands through the decoupling rectangular groove to achieve mutual coupling removal of the antenna units, a radiation pattern is corrected at the same time, and the isolation degree and radiation performance of an antenna port are improved on the premise that the patch size is not increased and the low profile is kept; and a new antenna solution is provided for a high-performance wireless communication system.

Description

Technical Field

[0001] This invention relates to an antenna for wireless communication, and more particularly to a dual-band MIMO decoupling patch antenna. Background Technology

[0002] Compared to single-frequency antennas, dual-frequency antennas can significantly improve the channel capacity and spectrum utilization efficiency of communication systems. However, with the rapid development of wireless communication technology, mutual coupling remains a key bottleneck limiting further improvements in system performance. Mutual interference between antennas can lead to a series of problems, including poor impedance matching, distorted radiation patterns, and a decline in overall radiation performance.

[0003] Most existing decoupling techniques are designed for single-frequency antennas. While they can effectively suppress coupling between single-frequency antennas, they are difficult to apply directly to dual-frequency antennas because the latter requires decoupling of both operating frequency bands simultaneously. Therefore, exploring mutual coupling suppression methods suitable for dual-frequency antenna arrays is of great significance.

[0004] Existing technologies propose a dual-band metasurface decoupling scheme, which achieves high isolation but introduces problems such as increased profile height and structural complexity. Furthermore, it does not address radiation pattern decoupling optimization, making it unsuitable for antenna arrays with high requirements for structural simplicity. To simultaneously achieve mutual coupling suppression and radiation pattern optimization in both frequency bands... Figure 1 To further improve the existing technology, an improved dual-frequency metasurface decoupling method is proposed. While maintaining low coupling and stable radiation pattern, there is still room for further optimization in terms of structural complexity and cross-sectional size. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a dual-band MIMO decoupling patch antenna based on a rectangular slot is proposed, which achieves self-decoupling and effective decoupling of the radiation pattern of the antenna in both frequency bands without increasing the size of the metal patch, while maintaining a low profile.

[0006] Technical solution: A dual-band MIMO decoupling patch antenna based on a rectangular slot, comprising a 1×2 antenna element array. The antenna element array adopts a symmetrical structure design, comprising a top metal layer, a dielectric substrate and a bottom metal layer stacked sequentially, and also includes a coaxial probe for feeding. The top metal layer includes two rectangular metal patches arranged side by side in the horizontal direction. Each rectangular metal patch has a dual-frequency rectangular groove parallel to the edge of the patch on its upper and lower edges. Each rectangular metal patch has decoupling rectangular grooves arranged horizontally on both sides of its upper part. In the vertical direction of the patch, the decoupling rectangular groove is located between the dual-frequency rectangular groove and the feed port formed by the coaxial probe. The inner conductor of the coaxial probe passes through the bottom metal layer and the dielectric substrate, and is connected to two rectangular metal patches to form a feed port. Dual-band resonance is achieved through the dual-frequency rectangular slot, and decoupling between the dual-band antenna elements and radiation pattern correction are achieved through the decoupling rectangular slot.

[0007] Furthermore, the feed point of the coaxial probe is located on the vertical centerline of the rectangular metal patch, and this feed point is located at TM. 10 The optimal excitation position of the module enables the rectangular metal patch to synchronously generate quasi-TM in both frequency bands. 10 The model radiates outwards.

[0008] Furthermore, the decoupling rectangular slot changes the distribution pattern of the induced electromagnetic field between adjacent rectangular metal patches, forming a dual-band weak field region at the feed position of the coupling patch, blocking the transmission of the induced electromagnetic field to the feed port, and realizing bidirectional decoupling between antenna elements.

[0009] Furthermore, the bottom metal layer is laid as a metal ground on the lower surface of the dielectric substrate, and the bottom metal layer is provided with a through hole through which the inner conductor for coaxial probe power supply passes.

[0010] Furthermore, the horizontal length of the rectangular metal patch is 0.3λ0-0.35λ0, and the vertical width is between 0.15λ0-0.20λ0; the side-to-side spacing between two rectangular metal patches is 0.035λ0-0.04λ0, where λ0 is the free space wavelength corresponding to the center frequency.

[0011] Furthermore, the upper and lower dual-frequency rectangular slots on a single rectangular metal patch are symmetrical about the horizontal centerline of the patch, and all dual-frequency rectangular slots have the same dimensions, with a slot length of 0.25λ0-0.3λ0 and a slot width of 0.0015λ0-0.002λ0, where λ0 is the free space wavelength corresponding to the center frequency; the distance between the edge of the dual-frequency rectangular slot and the edge of the corresponding rectangular metal patch is 0.0015λ0-0.002λ0.

[0012] Furthermore, each of the decoupling rectangular slots has the same dimensions, with a slot length of 0.1λ0-0.15λ0 and a slot width of 0.01λ0-0.015λ0.

[0013] Furthermore, on a single rectangular metal patch, the distance between the lower edge of the upper dual-frequency rectangular groove and the upper edge of the decoupling rectangular groove is 0.0035λ0-0.004λ0.

[0014] Beneficial Effects: Current single-frequency antenna decoupling techniques are difficult to directly transfer to dual-frequency antenna applications. Furthermore, existing dual-frequency decoupling antennas often face challenges related to profile height and structural complexity, and some designs still lack effective pattern decoupling functionality. This invention, by arranging two horizontally symmetrical rectangular slots on both sides of the upper part of two dual-frequency patch units with etched dual-slot structures, can simultaneously achieve self-decoupling of low and high frequencies and can also correct the radiation pattern. This invention provides a new solution for the application of dual-frequency decoupling antenna arrays in high-performance wireless communication systems. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the dual-frequency MIMO decoupling patch antenna of the present invention. Figure 2 This is a schematic diagram of the top metal layer structure of the dual-frequency MIMO decoupling patch antenna of the present invention; Figure 3 This is a schematic diagram of the bottom metal feeding structure of the dual-frequency MIMO decoupling patch antenna of the present invention; Figure 4 The S-parameters of the dual-band MIMO decoupling patch antenna are shown in the example. Figure 5 This is a gain curve of the dual-band MIMO decoupling patch antenna in the embodiment; Figure 6 The simulation radiation pattern of the dual-band MIMO decoupling patch antenna is shown in the example, where (a) corresponds to 3.5 GHz and (b) corresponds to 4.9 GHz. Detailed Implementation

[0016] The invention will now be further explained with reference to the accompanying drawings.

[0017] like Figures 1 to 3 As shown, this embodiment presents a dual-band MIMO decoupling patch antenna based on a rectangular slot, which integrates a 1×2 antenna element array and consists of a top metal layer 1, a dielectric substrate 2, a bottom metal layer 3, and a coaxial probe feed 4. The overall structure is symmetrical about the vertical plane of the dielectric substrate 2.

[0018] The top metal layer 1 includes rectangular metal patches 11 and 12 arranged side by side along the x-axis on the upper surface of the dielectric substrate 2.

[0019] The rectangular metal patch 11 has rectangular grooves 13 and 15 parallel to its edges at its top and bottom edges, respectively. The rectangular grooves 13 and 15 are symmetrical about the center line of the rectangular metal patch 11 along the x-axis. Similarly, the rectangular metal patch 12 has rectangular grooves 14 and 16 parallel to its edges at its top and bottom edges, respectively. The rectangular grooves 14 and 16 are symmetrical about the center line of the rectangular metal patch 12 along the x-axis.

[0020] The upper two sides of the rectangular metal patch 11 have rectangular grooves 17 and 18 along the x-axis, respectively, and the rectangular grooves 17 and 18 extend to both sides of the patch, forming single-sided through grooves; the rectangular grooves 17 and 18 are symmetrical about the center line of the rectangular metal patch 11 in the y-axis direction. Similarly, the upper two sides of the rectangular metal patch 12 have rectangular grooves 19 and 20 along the x-axis, respectively, and the rectangular grooves 19 and 20 are symmetrical about the center line of the rectangular metal patch 12 in the y-axis direction.

[0021] The bottom metal layer 3 serves as a ground plane and is disposed on the lower surface of the dielectric substrate 2. The inner conductors of the two coaxial probe feeds 4 pass through the bottom metal layer 3 and the dielectric substrate 2 respectively, and are then connected to the rectangular metal patches 11 and 12 to form feed ports 41 and 42. The bottom metal layer 3 is provided with corresponding through holes for the inner conductors of the coaxial probe feeds 4 to pass through.

[0022] The length (x-axis direction) of rectangular metal patches 11 and 12 is between 0.3λ0 and 0.35λ0, and the width (y-axis direction) is between 0.15λ0 and 0.20λ0, where λ0 is the free-space wavelength corresponding to the center frequency of 3.5GHz. The side-to-side spacing of rectangular metal patches 11 and 12 is between 0.035λ0 and 0.04λ0, and the center-to-center spacing is between 0.35λ0 and 0.40λ0. Rectangular metal patches 11 and 12 constitute the radiating structure of a 1×2 antenna element.

[0023] Rectangular slots 13, 14, 15, and 16 have identical dimensions: slot length (x-axis direction) between 0.25λ0 and 0.3λ0, and slot width (y-axis direction) between 0.0015λ0 and 0.002λ0. The distance between the upper edge of rectangular slots 13 and 14 and the upper edge of rectangular metal patches 11 and 12, as well as the distance between the lower edge of rectangular slots 15 and 16 and the lower edge of rectangular metal patches 11 and 12, are all between 0.0015λ0 and 0.002λ0. Rectangular slots 13, 14, 15, and 16 constitute a dual-frequency structure.

[0024] Rectangular slots 17, 18, 19, and 20 have identical dimensions, with slot lengths (x-axis direction) between 0.1λ0 and 0.15λ0, and slot widths (y-axis direction) between 0.01λ0 and 0.015λ0. The spacing between the lower edge of rectangular slot 13 and the upper edges of rectangular slots 17 and 18, as well as the spacing between the lower edge of rectangular slot 14 and the upper edges of rectangular slots 19 and 20, are identical, all between 0.0035λ0 and 0.004λ0. Rectangular slots 17, 18, 19, and 20 constitute a decoupled structure for a 1×2 antenna element.

[0025] Two coaxial probes 4 form the feeding structure of a 1×2 antenna element, and the feed points connected to the rectangular metal patches 11 and 12 are located on the center lines of the y-axis of the rectangular metal patches 11 and 12, respectively. The arrangement direction of the rectangular slots 17, 18, 19, and 20 on the rectangular metal patches 11 and 12 is consistent with the direction of the line connecting the feed ports 41 and 42. Rectangular slots 17 and 18 are located between rectangular slot 13 and feed port 41 along the y-axis, and rectangular slots 19 and 20 are located between rectangular slot 14 and feed port 42 along the y-axis.

[0026] The excitation signal is fed into the rectangular metal patch 11 through the feed port 41, thereby generating quasi-TM signals simultaneously at 3.5 GHz and 4.9 GHz on the rectangular metal patch 11. 10 The mode radiates outwards. Thanks to the structure of rectangular slots 17, 18, 19, and 20, weak field regions are generated simultaneously at the two center frequencies of 3.5 GHz and 4.9 GHz at the feed positions on the mutually coupled rectangular metal patches 12. At this time, the energy of the weak field region cannot be transferred downwards to the feed port 42, so the feed port 42 cannot be excited, thereby achieving better isolation characteristics.

[0027] Specifically, the dual-band operation of this antenna is achieved by a dual-band structure consisting of rectangular slots 13, 14, 15, and 16 etched on the upper and lower edges of the rectangular metal patch. The dimensions of this dual-band structure are designed based on the free-space wavelength λ0 corresponding to the center frequency of 3.5 GHz, and each dual-band rectangular slot has the same size and a strictly symmetrical arrangement. The dual-band slot structures of the two patches are mirror images of each other. Combined with the overall symmetrical design of the antenna about the perpendicular plane of the dielectric substrate, this allows the radiated current to form different resonant transmission paths on the patches, respectively matching the wavelength characteristics of the low-frequency 3.5 GHz and the high-frequency 4.9 GHz. The coaxial probe feed point is located on the centerline of the rectangular metal patch along the y-axis, which is TM. 10 The optimal excitation position of the mode is determined by feeding the excitation signal into the patch through the feed port. Under the constraint of the dual-frequency slot, the radiated current forms a long-path resonance adapted to the 3.5GHz low frequency along the patch body and the outside of the slot, and a short-path resonance adapted to the 4.9GHz high frequency along the inside of the slot. The two resonance paths are independent of each other and do not interfere with each other. Ultimately, the patch synchronously generates a quasi-TM10 mode at the two center frequencies of 3.5GHz and 4.9GHz and radiates it outward, thereby realizing the dual-frequency operation characteristics of the antenna.

[0028] The dual-band decoupling function of this antenna is achieved by a decoupling structure consisting of rectangular slots 17, 18, 19, and 20 on both sides of the upper part of the rectangular metal patch. The dimensions of this decoupling structure are designed based on the free space wavelength λ0 corresponding to the center frequency of 3.5 GHz, and its spatial and dimensional design is adapted to the electromagnetic characteristics of the 3.5 GHz and 4.9 GHz dual-band frequencies. When the excitation signal is fed into the rectangular metal patch 11 through the feed port 41, the patch synchronously generates quasi-TM signals in both the 3.5 GHz and 4.9 GHz dual-band frequencies. 10 The antenna elements radiate outwards, and adjacent rectangular metal patches 12 generate induced electromagnetic fields due to electromagnetic coupling. Decoupling rectangular slots 17, 18, 19, and 20 utilize electromagnetic boundary conditions to alter the distribution of this induced electromagnetic field, causing the feed positions of the rectangular metal patches 12 to simultaneously form weak-field regions at the two center frequencies of 3.5 GHz and 4.9 GHz. The electromagnetic field energy in these weak-field regions is at an extremely low level, unable to propagate downwards along the metal patches to the feed port 42, thus preventing the feed port 42 from being excited by the induced electromagnetic field and fundamentally blocking the signal transmission path formed between antenna elements through electromagnetic coupling. Similarly, when the excitation signal is fed into the rectangular metal patch 12, the decoupling structure can form a dual-frequency weak-field region at the feed position of the rectangular metal patch 11, achieving bidirectional decoupling between antenna elements, thereby achieving port isolation and self-decoupling effects for the 1×2 antenna element array in both frequency bands. Meanwhile, during the process of regulating the electromagnetic field, the decoupled rectangular slot can optimize the distribution of radiated current on the two rectangular metal patches, avoid radiated current distortion caused by mutual coupling, correct the antenna radiation pattern, ensure the consistency of the radiation pattern under dual frequency bands, and improve the overall radiation performance of the antenna. Moreover, this decoupling structure design does not require increasing the antenna profile height or increasing the size of the metal patches, thus balancing structural simplicity with the optimization effects of dual-frequency decoupling and radiation pattern decoupling.

[0029] In this embodiment, the substrate material 2 is Rogers RO4003C, with a dielectric constant of 3.55 and a loss angle of 0.0027. The rectangular metal patches 11 and 12 have a length of 0.31λ0 and a width of 0.18λ0; the edge-to-edge spacing of the rectangular metal patches 11 and 12 is 0.037λ0, and the center-to-center spacing is 0.35λ0. The rectangular slots 13, 14, 15, and 16 have a slot length of 0.25λ0 and a slot width of 0.002λ0. The distance between the upper edge of the rectangular slots 13 and 14 and the upper edge of the rectangular metal patches 11 and 12, and the distance between the lower edge of the rectangular slots 15 and 16 and the lower edge of the rectangular metal patches 11 and 12, are 0.002λ0. The rectangular slots 17, 18, 19, and 20 have a length of 0.11λ0 and a width of 0.013λ0. The distance between the lower edge of rectangular groove 13 and the upper edge of rectangular grooves 17 and 18, and the distance between the lower edge of rectangular groove 14 and the upper edge of rectangular grooves 19 and 20 along the y-axis direction are 0.0036λ0.

[0030] The simulation results of antenna matching, isolation, and gain response in this embodiment are as follows: Figure 4 , Figure 5 As shown, the antenna in this embodiment has an impedance matching bandwidth of 0.34% at 3.5 GHz and 0.71% at 4.9 GHz. The maximum gain is 2.65 dB at 3.5 GHz and 2.23 dB at 4.9 GHz. The isolation is greater than 18.62 dB at 3.5 GHz and greater than 23.39 dB at 4.9 GHz. Figure 4 As shown, the simulated H-plane radiation pattern of this antenna at 3.5 GHz has a 3-dB beamwidth of 89° in the H-plane and a cross-polarization level of -19.4 dB within the 3-dB beamwidth. Figure 5 As shown, the simulated H-plane radiation pattern of the antenna at 4.9 GHz has a 3-dB beamwidth of 92.3° in the H-plane and a cross-polarization level of -10.8 dB within the 3-dB beamwidth in the H-plane.

[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A dual-frequency MIMO decoupling patch antenna based on a rectangular slot, characterized in that, It includes a 1×2 antenna element array, which adopts a symmetrical structure design, including a top metal layer, a dielectric substrate and a bottom metal layer stacked in sequence, and also includes a coaxial probe for feeding. The top metal layer includes two rectangular metal patches arranged side by side in the horizontal direction. Each rectangular metal patch has a dual-frequency rectangular groove parallel to the edge of the patch on its upper and lower edges. Each rectangular metal patch has decoupling rectangular grooves arranged horizontally on both sides of its upper part. In the vertical direction of the patch, the decoupling rectangular groove is located between the dual-frequency rectangular groove and the feed port formed by the coaxial probe. The inner conductor of the coaxial probe passes through the bottom metal layer and the dielectric substrate, and is connected to two rectangular metal patches to form a feed port. Dual-band resonance is achieved through the dual-frequency rectangular slot, and decoupling between the dual-band antenna elements and radiation pattern correction are achieved through the decoupling rectangular slot.

2. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 1, characterized in that, The feed point of the coaxial probe is located on the vertical centerline of the rectangular metal patch, and this feed point is located at TM. 10 The optimal excitation position of the module enables the rectangular metal patch to synchronously generate quasi-TM in both frequency bands. 10 The model radiates outwards.

3. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 1, characterized in that, The decoupling rectangular slot changes the distribution pattern of the induced electromagnetic field between adjacent rectangular metal patches, forming a dual-band weak field region at the feed position of the coupling patch, blocking the transmission of the induced electromagnetic field to the feed port, and realizing bidirectional decoupling between antenna elements.

4. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 1, characterized in that, The bottom metal layer is laid as a metal ground on the lower surface of the dielectric substrate, and a through hole is provided on the bottom metal layer for the inner conductor to pass through for power feeding of the coaxial probe.

5. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to any one of claims 1-4, characterized in that, The horizontal length of the rectangular metal patch is 0.3λ0-0.35λ0, and the vertical width is between 0.15λ0-0.20λ0; the side-to-side spacing between two rectangular metal patches is 0.035λ0-0.04λ0, where λ0 is the free space wavelength corresponding to the center frequency.

6. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 5, characterized in that, The upper and lower dual-frequency rectangular slots on a single rectangular metal patch are symmetrical about the horizontal centerline of the patch. All dual-frequency rectangular slots have the same dimensions, with a slot length of 0.25λ0-0.3λ0 and a slot width of 0.0015λ0-0.002λ0, where λ0 is the free space wavelength corresponding to the center frequency. The distance between the edge of the dual-frequency rectangular slot and the edge of the corresponding rectangular metal patch is 0.0015λ0-0.002λ0.

7. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 5, characterized in that, Each of the decoupling rectangular slots has the same dimensions, with a slot length of 0.1λ0-0.15λ0 and a slot width of 0.01λ0-0.015λ0.

8. The dual-frequency MIMO decoupling patch antenna based on a rectangular slot according to claim 5, characterized in that, On a single rectangular metal patch, the distance between the lower edge of the upper dual-frequency rectangular groove and the upper edge of the decoupling rectangular groove is 0.0035λ0-0.004λ0.

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