随着航天技术的革新，对近地轨道的通信需求逐年增高。近地轨道卫星就在此背景下产生，主要应用于遥感探测天气预报和数据通信领域。由于近地轨道卫星天线辐射波束所覆盖的地球表面是球面，因此波束通常设计为等通量形式。由于卫星通信通常存在极化失配、多径效应等问题，选择多极化而不是圆极化作为近地卫星天线的工作状态能更好地适应复杂的工作环境，保证通信质量，将等通量波束天线和多极化可重构技术结合起来有很大的应用前景。基于一对正交圆极化波能合成线极化波的设计原理，文中提出了一种具有等通量波束的多极化可重构天线，该天线由可重构馈电网络和带扼流环的隔片极化器圆波导组成。馈电网络中嵌入单刀四掷开关（SP4T）与单刀双掷开关（SP2T），通过改变开关的工作状态，馈电网络将给圆波导提供不同的馈电条件，在圆波导内隔片的作用下天线实现两种圆极化与两种线极化的可重构。通过在圆波导口引入扼流环以及波导口作“T”型开槽处理，实现波束赋形，并且保证天线在不同极化状态下辐射等通量波束。实测结果显示，天线在不同的极化状态下-15 dB重叠阻抗带宽14.7%，覆盖4.80~5.56 GHz，方向图顶部在\theta为-24°~+24°范围内具有平坦效果，圆极化状态下空间轴比覆盖-51°~+50°，覆盖范围大于方向图顶部平坦范围。天线实测结果与仿真结果有较好的一致性，具有多极化和方向图顶部平坦的优势，可满足移动通信和卫星通信中多极化应用场景的需要。

With the innovation of space technology, the demand for low earth orbit communication is increasing year by year. Low earth orbit satellites produced in this context are mainly used in remote sensing detection, weather forecasting and data communication fields. Because the earth surface covered by the antenna beam of low earth orbit satellite is spherical, the beam is usually designed as the equal flux form. Because of the problems of polarization mismatch and multipath effect in satellite communication, choosing multipolarization rather than circular polarization as the working state of low earth orbit satellite antenna can better adapt to the complex working environment and ensure the quality of communication. The combination of equal flux beam antenna and multipolarization reconfigurable technology has great application prospects. Based on the design principle of synthesizing linearly polarized waves from a pair of orthogonal circularly polarized waves, a multi-polarization reconfigurable antenna with isoflux beam was proposed in this paper. The antenna consists of a reconfigurable feeding network and a septum polarizer circular waveguide with choke rings. By changing the working states of SP4T switch and SP2T switches embedded in the feeding network, the feeding network will provide different feeding conditions to the circular waveguide, and the antenna can be reconfigured with two kinds of circular polarizations and two kinds of linear polarizations under the action of the septum in the circular waveguide. In addition, the beamforming was realized by introducing choke rings and T-shaped slots structures into the circular waveguide,which ensures that the antenna radiates isoflux pattern under different polarization states. The measured results show that the overlapping impedance bandwidth of -15 dB is 14.7%, covering 4.80~5.56 GHz, and the top of the radiation pattern has a flat effect in the range of θ from -24° to +24°. In the circular polarization states, the spatial axis ratio covers from -51° to +50°, and the coverage range is larger than the flat range at the top of the pattern. The measured results are in good agreement with the simulation results, and the antenna has the advantages of multi-polarization and flat top of the pattern, which can meet the needs of multi-polarization application scenarios in mobile communication and satellite communication.