Research On Broadband Planar Reflect Array Antennas

Planar reflectarray antennas have attracted the attention of many scholars because of the characteristics of high gain,low profile,easy processing,and simple feeding network.Circularly polarized planar reflectarray antennas have a strong anti-interference ability,which can overcome the influence of the multipath effects and the interference of rain and fog,so it can be widely used in the field of satellite communications.The folded reflectarray antenna is developed based on the traditional reflectarray antenna.Compared with the ordinary reflectarray antenna,the folded reflectarray antenna has a lower profile(the profile is about half that of the ordinary reflectarray antenna),and its feeding source is easier to integrate with the reflectarray,which can avoid the shield for the antenna radiation by the feeding source and the bracket.The main contents and innovations of this paper are as follows:Firstly,the history and research status of the planar reflectarray antennas are summarized.The working principles and design methods of planar reflectarray antennas are analyzed.In view of the narrow bandwidth of the planar reflectarray antennas,the factors that influence the planar reflectarray bandwidth are analyzed.Secondly,a W-band dual-resonant broadband reflection unit is proposed.The unit is based on a cross-shaped patch unit.Two pairs of rectangular patches are added around the crossshaped patch unit to form a dual-resonant structure,which can widen the bandwidth of the unit and achieve a flat phase shift curve with a phase range exceeding 450°.In addition,by adjusting the size of the unit in the orthogonal direction,the reflection phase of the orthogonally polarized incident wave can be controlled independently to achieve the conversion from linear polarization to circular polarization and the polarization rotation by 90°.Based on this unit,a broadband circularly polarized planar reflectarray antenna and a broadband linearly polarized folded planar reflecarray antenna are designed,processed and tested.The measured results of the broadband circularly polarized planar reflectarray antenna show that both the-10 d B impedance bandwidth and the 3 d B gain bandwidth can reach 11.6%(80 GHz to 90 GHz),and the antenna gains are greater than 25 d B over the entire bandwidth.The measurements are basically consistent with the simulated results.The simulated axial ratio is less than 3d B over the entire bandwidth,and the measured axial ratio is slightly worse due to the processing and assembling errors,but all of the measured values are less than 4 d B.The measured results of the broadband linearly polarized folded planar reflectarray antenna show that both the-10 d B impedance bandwidth and the 3 d B gain bandwidth can reach 22.2%(80 GHz ～ 100 GHz),and the antenna gains are greater than 24 d B in the entire bandwidth.The measured results are basically consistent with the simulation results.Thirdly,a Ka-band dual-resonant broadband reflection unit is proposed.The unit consists of the Jerusalem cross patch,which is around bytwo pairs of rectangular patches.It has a flat phase shift curve with a phase shift range of 450 °.By adjusting the size of the unit in the orthogonal direction,the reflection phase of the orthogonally polarized incident wave can be controlled independently.Based on the unit,a broadband circularly polarized planar reflectarray antenna and a broadband linearly polarized folded planar reflectarray antenna are designed,processed and tested.The measured results of the broadband circularly polarized planar reflectarray antenna show that both the-10 d B impedance bandwidth and the 3 d B gain bandwidth can reach 25.7%(30 GHz to 39 GHz),and the gains are greater than 23.5 d B in the entire bandwidth.The measured results are basically consistent with the simulation results.The3 d B axial ratio bandwidth reaches 22.8%(30 GHz ～ 38 GHz),and the measured axial ratio is slightly worse due to processing and assembly errors,but all of the measured values are less than 4 d B.The measurement results of the broadband linearly polarized folded planar reflectarray antenna show that both the-10 d B impedance bandwidth and the 3 d B gain bandwidth can reach 22.2%(31 GHz ～ 40 GHz),and the antenna gains are greater than 25.5d B in the entire bandwidth.The measured results are basically consistent with the simulation results.