Design Of Polarization Reconfigurable Ship Radar Antenna

Navigation radar is an important equipment on ship.Antenna,as an important part of radar,directly affects the performance of radar.The polarization modes of marine radar antennas are mostly horizontal polarization and circular polarization.Horizontally polarized antennas can reduce the impact of sea wave clutter,and circularly polarized antennas are highly resistant to rain and fog interference.Therefore,in order to adapt ship radar antennas to different application environments,two antennas with different polarization modes are required,resulting in increase in system volume and cost.In order to solve this problem,this thesis proposes a solution of designing a polarized reconfigurable antenna for ship radar.The advantage of using polarization reconfigurable antenna is the polarization mode of the antenna can be easily switched according to the application environment,so that the antenna always works in the best polarization state,and its size is small and the cost is low.Therefore,it is of great significance to study the design and implementation methods of polarization reconfigurable antenna for ship radar.At present,marine radar antennas mainly include waveguide slot antenna arrays and microstrip antenna arrays.Since the Substrate Integrated Waveguide(SIW)has the advantages of both waveguide and microstrip line,this article studies the design and implementation methods of an X-band polarized reconfigurable marine radar antenna based on the SIW structure.The main research contents and results are as follows:(1)An X-band vertical polarization SIW slot array antenna is designed.Vertical polarization is achieved by opening longitudinal slots on the wide side of the SIW;a wide frequency band is achieved by using a traveling wave array;a low sidelobe level is achieved by using a current distribution with Taylor distribution,and the surface current distribution is changed by changing the bias of the slot.According to the slot antenna and antenna array theory,the antenna array is designed,and the HFSS electromagnetic simulation software is used for simulation and optimization.The results show that the reflection coefficient of the antenna array in the 9～10GHz frequency band is less than-10 dB.At the center frequency of 9.4GHz,the horizontal main lobe width is 12.2°,the gain is 11.4dBi,and the sidelobe level is less than-18 dB.(2)An X-band horizontally polarized SIW wide-side V-shaped slot array antenna with high cross-polarization discrimination rate is designed.In order to achieve horizontal polarization,V-shaped slots are opened on the wide side of the SIW;in order to achieve a low sidelobe level,Taylor distribution slot antenna voltage distribution is adopted,and by changing the tilt angles of the slots to change the voltages at the slots.The method of theory design combining with simulation software simulation and optimization is used to design.The results show that the antenna array has a reflection coefficient of less than-10 dB in the 9.32～9.59 GHz frequency band.At the center frequency of 9.4GHz,the horizontal main lobe width is 9.6°,the gain is13.52 dBi,the sidelobe level is-20.4dB,and the cross-polarization discrimination rate is high,reaching 53.78 dB.(3)Based on the vertically polarized and the horizontally polarized SIW slot antenna arrays,a horizontally polarized/circularly polarized reconfigurable SIW slot antenna array is designed.First,combine the vertically polarized antenna array and the horizontally polarized antenna array to design a vertical/horizontal dual-polarized SIW slot antenna array.Then a Wilkinson power division feed network was designed.In order to combining the vertically polarized wave and the horizontally polarized wave into a circularly polarized wave,the power division ratio of the two output ports of the power divider is 2.2:1,and the phase difference is90°.By adding radio frequency switches to the feed network,a reconfigurable power divider is realized.The radio frequency switches control the on-off of the output ends of the power divider through the states of the diodes.When both output ends are channels,the horizontal polarization component lags the vertical polarization component by 90°,radiating right-handed circularly polarized wave;when only the branch to the horizontally polarized antenna array is a path,horizontally polarized wave is radiated.According to the design results,the polarized reconfigurable antenna array was processed and tested.The tested results show that the antenna array has horizontal polarization/circular polarization reconfigurable function,and in horizontal polarization mode,the horizontal main lobe width is 10°,the gain is 12.89 dBi,and the side lobe level is-19.1dB;in the right-hand circular polarization working mode,the horizontal main lobe width is 9.5°,the gain is 10.31 dBic,and the side lobe level is-17.8dB.The antenna array meets the requirements of low sidelobe level and horizontal polarization/circular polarization reconfigurability.At the same time,the antenna array also has the advantages of low cost and small size.