Directional radiation broadband circularly polarized slot antenna

Abstract

The utility model discloses a broadband circularly polarized slot antenna with directional radiation. The broadband circularly polarized slot antenna comprises a first-layer radiation structure and a second-layer metal reflection structure, the radiation structure comprises a dielectric substrate, two sections of feed microstrip lines, a triangular feed patch, a grounding plate and two square metal patches of which the opposite angles are cut off; the grounding plate is arranged on the lower surface of the dielectric substrate; a Z-shaped gap is etched in the grounding plate; the metal reflection structure comprises a metal reflection plane and four vertical metal baffle plates which are symmetrically distributed by taking the metal reflection plane as a center; and two rectangular gaps which are symmetrical left and right are cut off from the bottoms of the four vertical metal baffle plates. According to the utility model, the square metal patch of which the opposite angles are cut off is arranged at the Z-shaped slot, so that the working frequency of the slot antenna can be effectively reduced, and the transverse size of the antenna is indirectly reduced; the four vertical metal baffles are arranged on the metal reflection plane, and two rectangular gaps which are bilaterally symmetrical are cut off from the bottoms of the vertical metal baffles, so that the circular polarization bandwidth of the antenna can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of communication equipment, and particularly relates to a broadband circularly polarized slot antenna with directional radiation. Background Technique

[0002] In modern communication applications, circularly polarized antennas have been widely used due to their advantages such as no need for polarization matching, effective reduction of multipath interference and attenuation in signal transmission, and solution of the Faraday rotation problem. Examples include satellite communication, radio frequency identification (RFID) systems, wireless energy transfer, navigation and positioning (GPS, ultra-wideband UWB, Beidou navigation), etc.

[0003] Slot antennas are often used to design circularly polarized antennas and applied to Internet of Things communication devices because of their characteristics of compact structure, low profile, convenient processing, and low manufacturing cost. However, most of the existing broadband circularly polarized slot antennas on the market are bidirectional radiation with low gain, which greatly limits the application range of the antennas. Therefore, it is crucial to design a broadband circularly polarized slot antenna with directional radiation and high gain for improving the performance of communication systems. To achieve directional radiation, a metal reflector needs to be added to the slot antenna, but the distance from the reflector to the slot antenna often requires a quarter of the wavelength corresponding to the operating frequency of the antenna, resulting in a high profile of the directional radiation slot antenna. Yongsheng Pan et al. in "IEEE access" published "Low-profile Low-cost Ultra-wideband circularly polarized slot antennas" use a grid-shaped reflector instead of a pure metal reflector to achieve directional radiation. Although it can ensure broadband circular polarization at a low profile, the grid-shaped reflector is large in size, which will increase the volume of the antenna. At the same time, the grid-shaped reflector is fabricated using PCB technology, increasing the manufacturing cost of the antenna. Content of the Utility Model

[0004] The main purpose of the utility model is to overcome the disadvantages and deficiencies of the prior art, and propose a broadband circularly polarized slot antenna with directional radiation.

[0005] To achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A broadband circularly polarized slot antenna with directional radiation includes a radiation structure on the first layer and a metal reflection structure on the second layer;

[0007] The radiation structure includes a dielectric substrate, two sections of feeding microstrip lines, a triangular feeding patch, a ground plane, and two square metal patches with diagonals cut off;

[0008] The ground plane is disposed on the lower surface of the dielectric substrate; a Z-shaped slot is etched on the ground plane, and the Z-shaped slot is centrosymmetric about the center point of the ground plane; two-section feed microstrip lines and triangular feed patches are disposed on the upper surface of the dielectric substrate as the feed structure of the Z-shaped slot; two square metal patches with diagonal corners cut off are disposed in the Z-shaped slot and are centrosymmetric about the center point of the ground plane;

[0009] The metal reflection structure includes a metal reflection plane and four vertical metal baffles symmetrically distributed about the metal reflection plane; the four vertical metal baffles are respectively fixed on the four edges of the metal reflection plane and are higher than the metal reflection plane; two rectangular slots symmetrically cut off on the left and right are cut off at the bottom of the four vertical metal baffles.

[0010] Compared with the prior art, the present utility model has the following advantages and beneficial effects:

[0011] 1. For the present utility model, a broadband circularly polarized slot antenna with directional radiation, in order to reduce the size of the antenna, square metal patches with diagonal corners cut off are arranged on the Z-shaped slot of the first-layer radiation structure, and under the condition of ensuring a relatively wide impedance bandwidth, the operating frequency of the antenna is reduced; in the metal reflection structure of the second layer of the present utility model, four vertically metal baffles with central symmetry are added, which can effectively broaden the circularly polarized radiation bandwidth and realize directional broadband circularly polarized radiation without increasing the height of the antenna.

[0012] 2. In order to further broaden the circularly polarized bandwidth, two rectangular slots are cut off at the bottom of each vertical metal baffle in the present utility model, effectively improving the circularly polarized performance and circularly polarized bandwidth. Description of the Drawings

[0013] Figure 1 is a three-dimensional structural schematic diagram of the antenna according to the embodiment of the present utility model;

[0014] Figure 2 is a schematic diagram of the radiation structure of the antenna according to the embodiment of the present utility model;

[0015] Figure 3 is a schematic diagram of the metal reflection structure of the antenna according to the embodiment of the present utility model;

[0016] Figure 4 is the reflection coefficient curve of the antenna according to the embodiment of the present utility model;

[0017] Figure 5 is the axial ratio curve of the antenna according to the embodiment of the present utility model;

[0018] Figure 6 is the gain curve of the antenna according to the embodiment of the present utility model;

[0019] Figure 7a is the XOZ radiation pattern of the antenna according to the embodiment of the present utility model at 3.5 GHz;

[0020] Figure 7b is the YOZ radiation pattern of the antenna according to the embodiment of the present utility model at 3.5 GHz;

[0021] Figure 8a is the XOZ radiation pattern of the antenna according to the embodiment of the present utility model at 4.0 GHz;

[0022] Figure 8b is the YOZ radiation pattern of the antenna according to the embodiment of the present utility model at 4.0 GHz;

[0023] Figure 9a is the XOZ radiation pattern of the antenna according to the embodiment of the present utility model at 4.5 GHz;

[0024] Figure 9b is the YOZ radiation pattern of the antenna according to the embodiment of the present utility model at 4.5 GHz;

[0025] Explanation of the reference numerals in the drawings: 1 - radiation structure; 2 - metal reflection structure; 3 - first - stage feeding microstrip line; 4 - second - stage feeding microstrip line; 5 - triangular feeding patch; 6 - plastic column; 7 - SMA connector; 8 - inner core of the SMA connector; 9 - circular slot; 10 - square metal patch with diagonals cut off; 11 - ground plane; 12 - Z - shaped slot; 13 - vertical metal baffle; 14 - rectangular slot. Detailed implementation manners

[0026] The present utility model will be further described in detail below in conjunction with the embodiments and the drawings, but the implementation manners of the present utility model are not limited thereto.

[0027] Embodiment

[0028] As Figure 1 、 Figure 2 and Figure 3 shown, the present utility model, a broadband circularly - polarized slot antenna with directional radiation, includes a radiation structure 1 in the first layer and a metal reflection structure 2 in the second layer;

[0029] The radiation structure includes a dielectric substrate, a first - stage feeding microstrip line 3, a second - stage feeding microstrip line 4, a triangular feeding patch 5, a ground plane 11, and two square metal patches 10 with diagonals cut off;

[0030] The ground plane is disposed on the lower surface of the dielectric substrate, and the shape of the ground plane is a square with a pair of opposite corners cut off; a Z-shaped slot 12 is etched on the ground plane, and the Z-shaped slot is centrosymmetric about the center point of the ground plane; two sections of feeding microstrip lines and a triangular feeding patch are used as the feeding structure of the Z-shaped slot and are disposed on the upper surface of the dielectric substrate; two square metal patches with opposite corners cut off are disposed in the Z-shaped slot and are centrosymmetric about the center point of the ground plane; a circular slot 9 is opened at the center of the square metal patch.

[0031] The metal reflection structure includes a metal reflection plane and four vertical metal baffles 13 symmetrically distributed about the metal reflection plane; the four vertical metal baffles are respectively fixed on the four edges of the metal reflection plane and are higher than the metal reflection plane; two rectangular slots 14 symmetrically cut off on the left and right are cut off at the bottom of the four vertical metal baffles. The four vertical metal baffles and the metal reflection plane are integrally formed.

[0032] In this embodiment, the feeding microstrip line is fed by an SMA connector 7;

[0033] The grounding end of the SMA connector is welded to the ground plane, and the inner core 8 of the SMA connector is welded to the feeding microstrip line.

[0034] In this embodiment, as Figure 1 shown, there are also four plastic columns 6, two of which pass through the circular slot of the square metal patch and are used to fix the radiation structure of the first layer and the reflection metal structure of the second layer; the height of the plastic column is set to the distance between the metal reflection plane and the dielectric substrate, specifically 12 mm.

[0035] In this embodiment, the material of the dielectric substrate is epoxy resin;

[0036] The width of the first section of the feeding microstrip line 3 is 2.7 mm, and the width of the second section of the feeding microstrip line 4 is 0.7 mm.

[0037] The side length of the square metal patch is 16 mm, and the length of the cut-off diagonal is 5 mm.

[0038] The thickness of the four vertical metal baffles is 1 mm, the broadband is 19 mm, and the height is 13.6 mm; the width of the rectangular groove at the bottom of the four vertical metal baffles is 2.6 mm, and the length is 7.75 mm.

[0039] The metal reflection plane is a square with a side length of 47 mm and a thickness of 1 mm.

[0040] In this embodiment, the radiation structure is fabricated by PCB technology.

[0041] The present utility model adopts a centrally symmetric Z-shaped slot as the radiation structure. The Z-shaped slot is etched on the ground plane of the antenna, and the ground plane is arranged on the lower surface of the dielectric substrate; a pair of diagonals of the ground plane of the antenna are cut off to generate circularly polarized radiation for the antenna; two square metal patches with cut-off diagonals are arranged in the Z-shaped slot to effectively reduce the operating frequency of the antenna and reduce the lateral size of the antenna. For the metal reflection structure of the second layer, four centrally symmetric vertical metal baffles are arranged at the edge of the metal reflection plane. On the premise of maintaining directional radiation, the circular polarization performance of the antenna is effectively improved to achieve broadband circularly polarized radiation. Without increasing the height of the antenna, the influence of the horizontal metal reflection plane on the slot antenna is weakened, effectively reducing the profile of the antenna; two rectangular slots are cut off at the bottom of each vertical metal baffle, which can effectively optimize the circularly polarized radiation of the antenna and further increase the circular polarization bandwidth. The antenna is fed by an SMA connector. The grounding end of the SMA connector is welded to the ground plane of the radiation structure, and its inner core is welded to the feeding microstrip line of the radiation structure, so that the antenna has better impedance matching, thereby obtaining a wider impedance bandwidth without increasing the profile height and lateral size of the antenna.

[0042] As Figure 4 and Figure 5 shown, they are respectively the reflection coefficient curve and the axial ratio curve of the directional broadband circularly polarized slot antenna of this embodiment. As shown in the figure, the antenna has a very wide impedance bandwidth and circular polarization bandwidth. The impedance bandwidth can reach 46.5% (3.02 - 4.85 GHz), while the 3 dB axial ratio bandwidth is 42.9% (3.15 - 4.87 GHz), and the overlapping bandwidth of impedance and axial ratio is 42.5% (3.15 - 4.85 GHz).

[0043] As Figure 6 shown, it is the gain curve of the antenna of this embodiment. It can be seen from the figure that the highest gain within the overlapping bandwidth of impedance and 3 dB axial ratio reaches 6.5 dBic.

[0044] The radiation patterns of the antenna of this embodiment in the XOZ and YOZ planes at 3.5 GHz are as Figure 7a and Figure 7b shown; the radiation patterns in the XOZ and YOZ planes at 4.0 GHz are as Figure 8a and Figure 8b shown; the radiation patterns in the XOZ and YOZ planes at 4.5 GHz are as Figure 9a and Figure 9b shown. It can be seen that the radiation pattern of the antenna shows directional radiation, radiating along the Z-axis direction, the radiation polarization mode is right-handed circular polarization, and the back lobe of the radiation pattern is small.

[0045] For the broadband circularly polarized slot antenna of the present utility model, the designer can determine the size of the Z-shaped slot and the size of the square metal patch with cut-off diagonals according to the required frequency band.

[0046] It should also be noted that in this specification, terms such as "including", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0047] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A broadband circularly polarized slot antenna with directional radiation, characterized in that: A radiation structure comprising a first layer and a metal reflection structure comprising a second layer; The radiation structure includes a dielectric substrate, two sections of feeding microstrip lines, a triangular feeding patch, a ground plane, and two square metal patches with opposite corners cut off; A ground plate is arranged on the lower surface of a dielectric substrate; a Z-shaped gap is etched on the ground plate, and the Z-shaped gap is centrally symmetrical about the center point of the ground plate; two sections of feeding microstrip lines and a triangular feeding patch are arranged on the upper surface of the dielectric substrate as a feeding structure of the Z-shaped gap; two square metal patches with diagonal cuts are arranged in the Z-shaped gap, and are centrally symmetrical about the center point of the ground plate; The metal reflection structure includes a metal reflection plane and four vertical metal baffles symmetrically distributed around the metal reflection plane; the four vertical metal baffles are respectively fixed on the four edges of the metal reflection plane and are higher than the metal reflection plane; two left-right symmetrical rectangular gaps are cut from the bottom of the four vertical metal baffles.

2. A directional radiation broadband circularly polarized slot antenna according to claim 1, characterized in that: The ground plate is in the shape of a square with a pair of opposite corners cut off.

3. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: A circular gap is opened in the center of the square metal patch.

4. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: Four vertical metal baffles are integrally formed with the metal reflective plane.

5. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: The feeding microstrip line uses an SMA connector for feeding; The ground terminal of the SMA connector is welded to the ground plate, and the inner core of the SMA connector is welded to the feeding microstrip line.

6. The broadband circularly polarized slot antenna with directional radiation according to claim 3, characterized in that: It also includes a plastic column, which passes through the circular gap of the square metal patch and is used to fix the radiation structure of the first layer and the reflective metal structure of the second layer; The height of the plastic column is set to be the distance between the metal reflective plane and the dielectric substrate, specifically 12 mm.

7. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: The width of the first section of the feeding microstrip line is 2.7 mm, and the width of the second section of the feeding microstrip line is 0.7 mm.

8. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: The side length of the square metal patch is 16 mm, and the cut diagonal length is 5 mm.

9. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: The four vertical metal baffles are all 1mm thick, 19mm wide, and 13.6mm high; The rectangular slots at the bottom of the four vertical metal baffles are 2.6 mm wide and 7.75 mm long.

10. The broadband circularly polarized slot antenna with directional radiation according to claim 1, characterized in that: The metal reflective plane is a square with a side length of 47 mm and a thickness of 1 mm.

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