Research And Design Of Antenna Based On Substrate Integrated Waveguide

With the rapid development of wireless communication technology,traditional microstrip antenna can no longer meet the development needs,so Substrate Integrated Waveguide（SIW）antenna becomes a better choice.Compared with the traditional planar transmission lines such as microstrip lines,the substrate integrated waveguide structure has the advantages of high Q value,low loss and easy integration.It is a three-dimensional periodic structure made by adding periodic metallization through holes between the upper and lower metal surfaces.The metallization through holes play a similar role to the electric wall.Based on the above characteristics of SIW,this structure is analyzed and simulated.The specific research results are as follows:1.A miniaturized SIW back-cavity slot antenna based on two-layer metasurface element is proposed.Firstly,according to the design principle of the back cavity slot antenna,a SIW back cavity slot antenna working near 10GHz is designed.Then,a 4×4 metasurface array composed of square metal patch elements was designed to take advantage of the miniaturization characteristics of the metasurface.The SIW back-cavity slot antenna loaded with the array worked at 8.67GHz,thus achieving the reduction of electrical size.Finally,Giuseppe Peano’s fractal theory is used to design a2×2 metasurface array composed of fractal elements,and the array is loaded on top of the 4×4metasurface array to form a SIW back-cavity gap antenna based on the two-layer metasurface element.The resonant frequency of the antenna decreases from 8.67GHz to 6.5GHz,and the electrical size of the antenna decreases by 35%compared with that of the SIW back-cavity gap antenna without the metasurface element.2.A polarization reconfigurable antenna based on SIW structure is proposed.Firstly,the resonant frequency of the antenna is determined and the original resonant cavity size is designed.Then,according to the electric field distribution and surface current distribution of TE₁₀₂ and TE₂₀₁ modes in the resonant cavity,four rectangular gaps were loaded in the middle and edge regions of the upper surface.The disturbance was introduced by adjusting the gap length appropriately,so as to realize circular polarization.Finally,the diode state loaded on the gap is controlled to realize the conversion between two kinds of circular polarization and linear polarization（Linear Polarization,LP）.The simulation results show that the axial ratio（AR）bandwidth of the antenna reaches 0.8%and 0.6%in the two circular polarization states,and the relative impedance bandwidth of the LP is 1.4%,and the peak gain of the antenna reaches more than 4d Bi in the three states.3.A novel polarization reconfigurable antenna based on SIW structure is proposed.Firstly,according to the resonant frequency formula of the SIW,the resonant cavity size is calculated from the preset resonant frequency.Then a square annular gap is introduced on the upper surface of the cavity to cut the surface currents of TE₁₀₂ and TE₂₀₁ modes,and four parasitic tangent angles are introduced to make the phase difference between the two modes 90°.Then the four parasitic cutting angles are connected with the internal octagon patch by four diodes,and the switch of left circular polarization（Left-Hand Circular Polarization,LHCP）,right circular polarization（Right-Hand Circular Polarization,RHCP）and LP can be realized.Due to the particularity of the structure,the bias circuit of the antenna is simpler than other reconfigurable antennas,so the performance is better.Finally,physical machining and measurement are carried out.The measurement results show that the gain of the antenna under the three polarization modes reaches about 6d Bi,compared with the existing SIW polarization reconfigurable antenna,the performance of gain and bandwidth are greatly advantageous.