An asymmetric antenna array structure based on weak field self-decoupling

Abstract

The present invention relates to the field of antenna transmission, and in particular to an asymmetric antenna array structure based on weak field self-decoupling. The structure includes a dielectric plate, a patch antenna, and an antenna array element. The patch antenna and the antenna array element are both arranged on the dielectric plate. The patch antenna includes a patch and an embedded microstrip line. The patch is divided into a middle patch and a side patch. Both sides of the middle patch are connected to side patches. A slot is provided at the connection between the middle patch and the side patch. Two microstrip lines are connected to the two ends of the middle patch. The ends of the microstrip lines are connected to coaxial probes. The sizes of the microstrip lines and the slots are set so that the microstrip line radiation and the patch radiation at adjacent antenna array elements in the antenna array have the same amplitude and opposite phase. This structure designs an asymmetric MIMO system based on the weak field self-decoupling theory, realizes self-decoupling by structural design of the feed end, and uses differential feeding to adapt the self-decoupling design to the asymmetric array.

Description

Technical Field

[0001] The invention relates to the field of antenna transmission, and in particular to an asymmetric antenna array structure based on weak field self-decoupling. Background Art

[0002] Conventional MIMO array designs are all symmetrical, that is, the number of transmitting antennas is the same as the number of receiving antennas, or the antenna array is connected to the receiver and transmitter at the same time to switch working states. Such a design has reciprocity of transmission and reception, allowing the MIMO system to freely switch between transmission and reception with the same system. However, in 5G and future communication systems, symmetrical designs require more hardware resources and higher energy consumption, so asymmetric MIMO systems have been proposed to reduce system complexity and energy consumption. However, in the antenna array of an ordinary asymmetric system, the coupling between the receiving antenna and the transmitting unit is high, and additional transmission and reception decoupling design is required.

[0003] For decoupling technology, in some simple applications, increasing the spacing between array elements is a simple way to reduce coupling. When faced with complex arrays, existing methods for reducing the coupling between different antenna ports include using metamaterials to isolate surface waves on the periphery of the original antenna, or using parasitic units to create additional coupling paths around the antenna to reduce its coupling with other units in the array; or using orthogonal polarization, where the antenna units are configured in mutually orthogonal polarizations to reduce port coupling. However, the above technologies will make the original array structure more complex and increase the difficulty of processing. In order to reduce the difficulty of processing, a self-decoupling antenna technology based on weak fields was subsequently proposed, which is also based on field cancellation. In a single-port fed antenna array, a weak field can usually only be generated in a fixed direction, so this technology is difficult to play its role under the design requirements of a two-dimensional asymmetric antenna array.

[0004] The above decoupling methods have the following disadvantages: First, the symmetric MIMO system is highly complex and energy-intensive; second, if the antenna is not decoupled, the asymmetric array's transmit and receive antennas are highly coupled; third, the antenna process of adding an additional decoupling structure design is more complicated; fourth, the ordinary single-port self-decoupling design based on weak fields cannot adapt to two-dimensional asymmetric array structures. Summary of the invention

[0005] The present invention provides an asymmetric antenna array structure based on weak field self-decoupling, aiming to solve the shortcomings of the existing decoupling method.

[0006] The present invention provides an asymmetric antenna array structure based on weak field self-decoupling, comprising a dielectric plate, a patch antenna, and an antenna array element. The patch antenna and the antenna array element are both arranged on the dielectric plate. The patch antenna comprises a patch and an embedded microstrip line. The patch is divided into a middle patch and a side patch. Both sides of the middle patch are connected with side patches. A slot is arranged at the connection between the middle patch and the side patches. Two microstrip lines are connected at two ends of the middle patch. The ends of the microstrip lines are connected to coaxial probes. By setting the sizes of the microstrip lines and the slots, the microstrip line radiation and the patch radiation at adjacent antenna array elements in the antenna array have the same amplitude and opposite phase.

[0007] As a further improvement of the present invention, the antenna array element includes a grid antenna array element, the patch antenna is located at the center of the dielectric plate as a receiving antenna, and multiple grid antenna array elements form a two-dimensional array with the patch antenna as the center as a transmitting antenna, and the radiation of the multiple grid antenna array elements is superimposed on each other to form a weak field.

[0008] As a further improvement of the present invention, the distance between the feed point port of the microstrip line and the adjacent grid antenna array element is smaller than the distance between the patch and the adjacent grid antenna array element.

[0009] As a further improvement of the present invention, the grid antenna array elements of the transmitting antenna are placed at intervals of 1.8λ0 in the y direction and 1.2λ0 in the x direction, wherein λ0 is the wavelength in air.

[0010] As a further improvement of the present invention, the feeding part of the patch antenna is fed by two coaxial probes at the ends of the embedded microstrip lines to form differential feeding.

[0011] As a further improvement of the present invention, the material of the dielectric plate is Rogers5880.

[0012] As a further improvement of the present invention, the length of the patch is 0.5λ e , where λ e is the wavelength in the medium.

[0013] The beneficial effects of the present invention are as follows: the present structure designs an asymmetric MIMO system based on the weak field self-decoupling theory, realizes self-decoupling by structural design of the feeding end, and uses differential feeding to adapt the self-decoupling design to the asymmetric array. The feeding structure of the asymmetric antenna array is simple, the area is small, and the transmit-receive isolation is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural three-view diagram of the magnetoelectric dipole unit in the present invention;

[0015] Figure 2It is a top view of a single-layer 2×2 magnetoelectric dipole array with four-port feed that can switch between linear polarization and circular polarization in the present invention;

[0016] Figure 3 It is a ground plane current distribution diagram of the weak field-based self-decoupling differentially fed asymmetric array antenna receiving antenna excitation in the present invention;

[0017] Figure 4 is a reflection coefficient diagram of a receiving antenna port in the present invention;

[0018] Figure 5 is a diagram showing the reflection coefficient and coupling degree of the antenna port in the present invention;

[0019] Figure 6 is a frequency gain curve diagram of a receiving antenna in the present invention;

[0020] Figure 7 is the E-plane radiation pattern of the receiving antenna in the present invention;

[0021] Figure 8 is the H-plane directional pattern of the receiving antenna in the present invention;

[0022] Fig. 9 It is a ground plane current distribution diagram when the transmitting antenna of the weak field-based self-decoupling differential feeding asymmetric array antenna is excited;

[0023] Fig.10 is a reflection coefficient diagram of a transmitting antenna port in the present invention;

[0024] Fig.11 is a diagram showing the coupling degree of ports between transmitting antenna units in the present invention;

[0025] Fig.12 is a frequency gain curve diagram of the transmitting antenna in the present invention;

[0026] Fig.13 is the E-plane radiation pattern of the transmitting antenna in the present invention;

[0027] Fig.14 It is the H-plane radiation pattern of the transmitting antenna in the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1As shown, an asymmetric antenna array structure based on weak field self-decoupling of the present invention includes a dielectric plate 1, a patch antenna 2, and an antenna array element. The patch antenna 2 and the antenna array element are both arranged on the dielectric plate 1. The patch antenna 2 includes a patch and an embedded microstrip line 3. The patch is divided into a middle patch 21 and a side patch 22. Both sides of the middle patch 21 are connected to the side patches 22. A slot 23 is provided at the connection between the middle patch 21 and the side patches 22. Two microstrip lines 3 are connected to the two ends of the middle patch 21. The end of the microstrip line 3 is connected to a coaxial probe 4. By setting the sizes of the microstrip line 3 and the slot 23, the radiation of the microstrip line 3 and the patch radiation at adjacent antenna array elements in the antenna array have the same amplitude and opposite phase.

[0030] The antenna structure achieves self-decoupling by embedding the feed itself, and increases the weak field range generated by the self-decoupling structure through the differential structure. The main radiator of the antenna unit is the patch antenna 2, and the feed part uses a differential feed composed of two coaxial probes 4 at the end of the embedded microstrip line 3. The length L of the patch is about 0.5λ e , where λ e is the wavelength in the medium, so that the resonant frequency is at the operating frequency. Figure 1 By reasonably setting the feeder dimensions W0, L0, and the surrounding slot dimensions W1, L1, the feeder radiation and the patch radiation at the adjacent array elements in the array have the same amplitude and opposite phase, thus forming a weak field at the location of other array elements. The position of the weak field area is determined by these parameters, which need to be adjusted according to the situation of the array. The parameter settings used in the model in this embodiment are as shown in the following table. In the table, W represents the width of the patch, and dx represents the distance from the center of the coaxial probe 4 feed to the upper edge or lower edge.

[0031]

[0032] The distance between the feed port of the microstrip line 3 and the adjacent grid antenna element 5 is smaller than the distance between the patch and the adjacent grid antenna element 5. Since the radiation of the feed line is weaker than that of the patch, the feed port needs to be closer to the adjacent element. The differential feeding design makes the area where the weak field is formed more flexible and larger.

[0033] like Figure 2 As shown, the antenna array element includes a grid antenna array element 5, a patch antenna 2 is located at the center of the dielectric plate 1 as a receiving antenna, and multiple grid antenna array elements 5 form a two-dimensional array with the patch antenna 2 as the center as a transmitting antenna. The radiation of multiple grid antenna array elements 5 is superimposed on each other to form a weak field.

[0034] The transmitting antenna is a two-dimensional array composed of four grid antenna elements 5, and the center of the substrate is a self-decoupling patch antenna 2. The radiation of the sub-elements of the grid array unit overlaps each other to form a weak field, reducing the coupling degree of the transmitting antenna port, so that the grid array elements can also guarantee performance when they are close. The transmitting antenna elements are placed at intervals of 1.8λ0 in the y direction and 1.2λ0 in the x direction.

[0035] The dielectric plate 1 is made of Rogers 5880, with a thickness of 0.787 mm, a dielectric constant of 2.2, a loss tangent of 0.0009, and an overall size of 28.5 mm × 42.8 mm × 0.787 mm. The design of the present invention is the size of a single sub-array. According to needs, the dielectric plate can be expanded outward into different sizes with the same antenna element spacing.

[0036] When the asymmetric antenna array structure is working, the radiation generated by the antenna feed structure and the radiation of the patch cancel each other out at the position of the adjacent array element, resulting in a weak field in this area, thereby reducing the coupling between antennas. The coupling between antenna elements is mainly caused by the field of a certain antenna unit generating strong interference at the position of other antenna elements, which can be seen from Figure 3 It can be seen from the ground plane current distribution that most of the locations of the transmitting grid antenna array are in the area with weak current distribution.

[0037] The bandwidth and gain of the receiving antenna are as follows: Figures 4 to 8 As shown in the figure, at the operating frequency of 28 GHz, the coupling between the transmitting port and the differential port is significantly reduced, proving the effectiveness of this technology.

[0038] The performance of the receiving unit of the antenna array is shown in the following table, and it can be seen that it meets the performance requirements.

[0039] Sdd11 bandwidth 27.56~28.80GHz(1.24GHz) Sdd12 bandwidth >12GHz Maximum gain point (28.0GHz, 9.65dB) 3dB bandwidth 25.80~30.37GHz(4.57GHz) Main polarization and cross polarization levels <h2 style=";text-align:left;direction:ltr"><-35dB<h2 style=";text-align:left;direction:ltr">

[0040] Check the working status of the grid antenna array. The ground plane current distribution when the grid antenna is excited is as follows: Fig. 9 Even if the distance between the transmitting units is close, due to the generation of weak field, the ground plane current distribution at the location of the transmitting grid antenna is still maintained at a low level, which makes the structure of the entire antenna system compact and the area utilization rate high.

[0041] The bandwidth and gain of the transmitting antenna are shown as Figures 10 to 14 As shown in Figure 2, it can be seen that the grid structure has a larger bandwidth and a lower port coupling degree.

[0042] The performance of the transmitting unit of the antenna array is shown in the following table, and it can be seen that it meets the performance requirements.

[0043] Sdd11 bandwidth 25.41~29.44GHz(4.04GHz) Sdd12 bandwidth >12GHz Maximum gain point (28.25GHz, 19.27dB) 3dB bandwidth 26.15~30.81GHz(4.66GHz) Main polarization and cross polarization levels <-20dB

[0044] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. An asymmetric antenna array structure based on weak field self-decoupling, characterized in that: It comprises a dielectric plate, a patch antenna, and an antenna array element. The patch antenna and the antenna array element are both arranged on the dielectric plate. The patch antenna comprises a patch and an embedded microstrip line. The patch is divided into a middle patch and a side patch. Both sides of the middle patch are connected to side patches. A slot is provided at the connection between the middle patch and the side patches. Two microstrip lines are connected to the two ends of the middle patch. The ends of the microstrip lines are connected to a coaxial probe. By setting the sizes of the microstrip lines and the slots, the microstrip line radiation and the patch radiation at adjacent antenna array elements in the antenna array have the same amplitude and opposite phase. The antenna array element comprises a grid antenna array element, the patch antenna is located at the center of the dielectric plate as a receiving antenna, a plurality of the grid antenna array elements form a two-dimensional array with the patch antenna as the center as a transmitting antenna, and the radiation of the plurality of the grid antenna array elements is superimposed on each other to form a weak field; The distance between the feed point port of the microstrip line and the adjacent grid antenna array element is smaller than the distance between the patch and the adjacent grid antenna array element; The feeding part of the patch antenna is a differential feeding formed by feeding coaxial probes at the ends of two embedded microstrip lines; The length of the patch is 0.5λ e , where λ e is the wavelength in the medium.

2. The asymmetric antenna array structure based on weak field self-decoupling according to claim 1, characterized in that: The grid antenna elements of the transmitting antenna are arranged at intervals of 1.8λ0 in the y direction and 1.2λ0 in the x direction, wherein λ0 is the wavelength in air.

3. The asymmetric antenna array structure based on weak field self-decoupling according to claim 1, characterized in that: The material of the medium plate is Rogers5880.

Images