A new polarization reconfigurable antenna based on substrate integrated waveguide

Abstract

The present invention belongs to the technical field of microwave antennas, and specifically, is a novel polarization reconfigurable antenna based on substrate integrated waveguide, comprising two metal layers, one dielectric layer and a plurality of metal cylinders. From top to bottom, they are the first metal layer, the middle dielectric layer and the second metal layer. The first metal layer is a metal layer comprising a square annular gap; the second metal layer is a metal layer comprising a coplanar waveguide feeding structure. Four rectangular gaps connected end to end are etched on the first metal layer and four parasitic cut corners are additionally introduced. By loading four diodes at appropriate positions of the gaps, the antenna can be flexibly switched between linear polarization, left-hand circular polarization and right-hand circular polarization, and due to the particularity of the structure, the diode bias circuit is simpler, so the performance is better. The present invention realizes the polarization reconfigurable performance of the SIW back cavity slot antenna, while maintaining the working performance of the antenna in various states.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave antennas, and in particular, is a novel polarization reconfigurable antenna based on a substrate integrated waveguide. Background Art

[0002] With the growing demand for wireless communications, the problem of spectrum resource scarcity has become increasingly prominent. In order to effectively improve the utilization efficiency of resources, various reconfigurable antennas have emerged. Reconfigurable antennas can be divided into three types: polarization, frequency, and pattern reconfiguration. They often change the antenna's radiator or feed network by adding an appropriate amount of active devices such as diodes and varactor diodes at the gap. They are widely used because of their simple structure and rich functions. Circularly polarized antennas play an important role in the field of radio communications and are widely used. It can receive any linearly polarized wave, so when the circularly polarized antenna is used as a receiving antenna, the fault tolerance rate is high. Therefore, it is of great significance to design an antenna that can work in both circular and linear polarization states at the same time.

[0003] The paper “A Low-Profile Reconfigurable Cavity-Backed Slot Antenna With Frequency, Polarization, and Radiation Pattern Agility[J]. IEEE Transactions on Antennas & Propagation, 2017, PP(5):1-1.” proposes a SIW cavity-backed slot antenna that can reconfigure frequency, polarization, and radiation pattern. The antenna is made by etching cross-shaped slots on both the upper and lower surfaces of the SIW resonant cavity, and then adding diodes at the appropriate positions of the slots. By controlling the state of the diodes, the antenna can be reconfigured in frequency, radiation pattern, and polarization state. The antenna has a simple structure, but its operating bandwidth in various states is narrow and its gain within the operating frequency range is not high.

[0004] In the past, there were a lot of studies on reconfigurable antennas based on substrate integrated waveguides, but there were not many designs that took into account both the working bandwidth and gain performance. Therefore, it is of great significance to develop antennas with good working bandwidth and gain performance. Summary of the invention

[0005] In order to solve the technical problems mentioned in the background technology, the present invention provides a new polarization reconfigurable antenna based on substrate integrated waveguide, realizing a new idea of ​​polarization reconfiguration of SIW back-cavity slot antenna, and enabling the antenna to flexibly switch between linear polarization and two circular polarizations by loading diodes at appropriate slots on the radiating surface.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A new polarization reconfigurable antenna based on substrate integrated waveguide includes a first metal layer, an intermediate dielectric substrate, a second metal layer and several metal cylinders; the upper surface of the intermediate dielectric substrate is the first metal layer, the middle of the first metal layer has a square annular gap parallel to the periphery of the intermediate dielectric substrate, the interior of the square annular gap is composed of 4 parasitic cut corners, octagonal metal patches and 4 diodes, and the spacing between the 4 parasitic cut corners and the octagonal metal patches is equal, the spacing is consistent with the width of the square annular gap, and the octagonal metal patch is the main radiation patch of the antenna, and then a diode is placed between each parasitic cut corner and the main radiation patch, and a total of 4 diodes are placed. In addition, the first metal layer is the radiation surface of the antenna; the lower surface of the intermediate dielectric substrate is the second metal layer, which includes a grounded coplanar waveguide feeding structure; the metal cylinder runs through the intermediate dielectric substrate, and the two ends of the metal cylinder are respectively connected to the first metal layer and the second metal layer.

[0008] As a further optimization solution of the present invention, the intermediate dielectric substrate is made of Rogers 5880 material with a thickness of 1.575 mm, and the side length of the SIW resonant square cavity composed of the internal metal cylinders is 30 mm.

[0009] As a further optimization scheme of the present invention, the width and side length of the square annular gap of the first metal layer are determined according to design indicators, the width is between 0.5-0.9mm, preferably 0.8mm, the side length is between 12mm-14mm, preferably 13.5mm, and the spacing between the four parasitic cut corners and the octagonal metal patch is between 0.5-0.9mm, preferably 0.8mm.

[0010] As a further optimization scheme of the present invention, the inner metal strip of the grounded coplanar waveguide in the second metal layer is between 8-10 mm long, preferably 9 mm, and is between 0.4-0.8 mm wide, preferably 0.5 mm.

[0011] As a further optimization solution of the present invention, the distance between the parasitic cut angle of the first metal layer and the main radiation patch is determined according to design indicators.

[0012] As a further optimization solution of the present invention, the diode model is MADP-000907-14020.

[0013] As a further optimization solution of the present invention, the impedance of the microstrip line and the port are both 50 ohms.

[0014] The working principle of the present invention is as follows: a number of metal cylinders penetrate the intermediate dielectric substrate, and the two ends are connected to the first metal layer and the second metal layer, respectively, to form a SIW resonant cavity, thereby achieving the purpose of a low profile; the antenna feeds the resonant cavity through the grounded coplanar waveguide structure of the second metal layer, exciting the radiation slot of the first metal layer to radiate electromagnetic waves outward, and by controlling the state of the diode so that the corresponding slot is short-circuited or open-circuited, the radiation slot of the antenna changes, and left-hand circular polarization, right-hand circular polarization and linear polarization waves are generated. The entire antenna can obtain good radiation performance in three working states, and the relative working bandwidth in the linear polarization, left-hand circular polarization and right-hand circular polarization states reaches 4.4% and 1.8% respectively, and the radiation gain of about 6.5dBi can be achieved in the working frequency range of each state; compared with other types of SIW reconfigurable antennas, the relative working bandwidth and the radiation gain in the working frequency range of the present invention both show good performance.

[0015] The beneficial effects of the present invention are as follows: the present invention controls the diode state on the upper surface of the SIW resonant cavity to excite a pair of degenerate modes (TE102 mode and TE201 mode) inside the resonant cavity and makes the phase difference between the degenerate modes reach 90 degrees, so that the antenna can work in left-hand circular polarization and right-hand circular polarization states; the present invention controls the diode state on the upper surface of the SIW resonant cavity to excite the TE102 mode inside the resonant cavity, so that the antenna can work in a linear polarization state; the present invention proposes a novel design for realizing a SIW polarization reconfigurable antenna, and due to the independence of the parasitic patch, the bias circuit of the antenna is simpler than other SIW reconfigurable antennas, and the state of each diode can be controlled individually without adding additional active devices; the invention ultimately makes the SIW polarization reconfigurable antenna simpler in structure and easier to process while maintaining good radiation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a three-dimensional structural schematic diagram of the present invention.

[0017] Figure 2 It is a schematic diagram of the upper surface of the intermediate medium substrate of the present invention.

[0018] Figure 3 It is a schematic diagram of the lower surface of the intermediate dielectric substrate of the present invention.

[0019] Figure 4 1 is a simulated S parameter diagram of the embodiment of the present invention under linear polarization and two circular polarization states.

[0020] Figure 5 It is a simulated axial ratio diagram of the linear polarization and two circular polarization states of the embodiment of the present invention.

[0021] Figure 6It is a simulation gain diagram of the linear polarization and two circular polarization states of the embodiment of the present invention.

[0022] Figure 7 It is the E-plane simulation radiation pattern at 6.59 GHz in the linear polarization state of the embodiment of the present invention.

[0023] Figure 8 It is a simulated H-plane radiation pattern at 6.59 GHz in a linear polarization state according to an embodiment of the present invention.

[0024] Fig. 9 It is a simulated XOZ radiation pattern at 6.76 GHz in the left-hand circular polarization state of an embodiment of the present invention.

[0025] Fig.10 It is a YOZ simulation radiation pattern at 6.76 GHz in the left-hand circular polarization state of an embodiment of the present invention.

[0026] Fig.11 It is a simulated XOZ radiation pattern at 6.76 GHz in the right-hand circular polarization state of an embodiment of the present invention.

[0027] Fig.12 It is a YOZ simulation radiation pattern at 6.76 GHz in the right-hand circular polarization state of an embodiment of the present invention.

[0028] In the figure, 1-the first metal layer, 2-the intermediate dielectric substrate, 3-the second metal layer, 4-the metal cylinder, 5-the square annular gap, 6-the parasitic patch, 7-the octagonal metal patch, 8-the diode, and 9-the grounded coplanar waveguide feeding structure. DETAILED DESCRIPTION

[0029] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The embodiments are only used to explain the present invention and do not limit the protection scope of the present invention.

[0030] Embodiment: A polarization reconfigurable antenna based on substrate integrated waveguide, the structure is shown as follows Figures 1 to 3 As shown, Figure 1 It is a three-dimensional diagram of the structure, in which the first metal layer 1 is located on the upper surface of the intermediate dielectric substrate 2, the second metal layer 3 is located on the lower surface of the intermediate dielectric substrate 2, and the metal cylinder 4 penetrates the intermediate dielectric substrate 2, with the first metal layer 1 and the second metal layer 3 connected at both ends respectively; Figure 2The structure of the first metal layer 1 is shown schematically. The first metal layer 1 has a square annular gap 5. The four sides of the gap and the four sides of the intermediate dielectric substrate 2 are parallel to each other. First, four parasitic patches 6 are introduced into the square annular gap 5, so that the inside of the square annular gap is composed of four parasitic cut corners and an octagonal metal patch 7. The parasitic cut corners 6 and the octagonal metal patch 7 are separated by a certain distance, which is consistent with the width of the square annular gap 5. Then, the parasitic cut corners 6 and the octagonal metal patch 7 are connected by a diode 8. The width of the square annular gap, the number of diodes and the loading position are all important factors affecting the polarization reconfigurable performance of the antenna. Figure 3 The structure of the second metal layer 3 is shown schematically, including a grounded coplanar waveguide feeding structure 9 .

[0031] The intermediate dielectric substrate is made of Rogers 5880 material, with a thickness of 1.575 mm, and the side length of the SIW resonant square cavity composed of internal metal cylinders is 30 mm.

[0032] The width of the square annular gap in the first metal layer 1 is 0.8 mm and the side length is 13.5 mm; the spacing between the four parasitic cut corners and the internal main radiation patch is 0.8 mm, which is equal to the width of the square annular gap; the diode model loaded between the parasitic cut corners and the internal main radiation patch is MADP-000907-14020.

[0033] The inner metal strip of the grounded coplanar waveguide in the second metal layer 3 is 9 mm long and 0.5 mm wide.

[0034] The simulation results of the embodiment are as follows Figures 4 to 12 As shown, due to the symmetry of the structure, the working performance in the two circular polarization states is basically the same, wherein the simulation bandwidths of the antenna reflection coefficient less than -10dB in the linear polarization, left-hand circular polarization and right-hand circular polarization states are 6.45GHz-6.74GHz and 6.54GHz-7.09GHz respectively, the 3dB axial ratio bandwidth in the two circular polarization states covers 6.7GHz-6.82GHz, the gain of the antenna in the linear polarization and two circular polarization states within the working bandwidth is 6.08dBi-6.36dBi and 6.69dBi-6.87dBi respectively, and the front-to-back ratio of the antenna in the three states is greater than 20dB. The antenna shows good radiation performance in all states, indicating that the structure of the present invention can not only realize the flexible switching between linear polarization and two circular polarization states, but also has a simple structure, and the working bandwidth and radiation gain in each state are good.

[0035] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A new polarization reconfigurable antenna based on substrate integrated waveguide, It is characterized in that The invention comprises a first metal layer, an intermediate dielectric substrate, a second metal layer and a plurality of metal cylinders, wherein the upper surface of the intermediate dielectric substrate is the first metal layer, the middle of the first metal layer is provided with a square annular gap parallel to the periphery of the intermediate dielectric substrate, the interior of the square annular gap is composed of four parasitic cut corners, one octagonal metal patch and four diodes, the spacing between the four parasitic cut corners and the octagonal metal patch is equal, and the spacing is consistent with the width of the square annular gap, one diode is arranged between each parasitic cut corner and the octagonal metal patch, the lower surface of the intermediate dielectric substrate is the second metal layer, the surface of the second metal layer is provided with a grounded coplanar waveguide feeding structure, the metal cylinder passes through the intermediate dielectric substrate and the two ends are respectively connected to the first metal layer and the second metal layer.

2. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 1, It is characterized in that The thickness of the intermediate dielectric substrate is 1.575 mm, and the side length of the SIW resonant square cavity formed by the metal cylinders inside is 30 mm.

3. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 2, It is characterized in that The width of the square annular gap in the first metal layer is between 0.5-0.9 mm, the side length is between 12 mm-14 mm, and the spacing between the four parasitic cut corners and the octagonal metal patch is between 0.5-0.9 mm.

4. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 3, It is characterized in that The width of the square annular gap in the first metal layer is 0.8 mm, the side length is 13.5 mm, and the spacing between the four parasitic cut corners and the octagonal metal patch is 0.8 mm.

5. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to any one of claims 1 to 4, It is characterized in that The diode model is MADP-000907-14020.

6. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 5, It is characterized in that The inner metal strip of the grounded coplanar waveguide in the second metal layer is between 8 and 10 mm long and between 0.4 and 0.8 mm wide.

7. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 6, It is characterized in that The inner metal strip of the grounded coplanar waveguide in the second metal layer is 9 mm long and 0.5 mm wide.

8. The novel polarization reconfigurable antenna based on substrate integrated waveguide according to claim 7, It is characterized in that The impedance of the microstrip line and the port of the grounded coplanar waveguide in the second metal layer is 50 ohms.

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