毫米波高频段数字极化功率合成方法研究

As a key technology of the exploration of high millimeter wave region, power-combining can increase the output power capacity of single amplifier, which has important value in rapid developing applications, such as radar, communication, imaging, measurement, etc. However, due to the conventional scheme of divider, amplifier and combiner in cascade and the keen to domain-mode designing, the combining-efficiency cannot be software optimized, the mode type and polarization direction of the combined-wave cannot be real-time control, and the structure is difficult in scaling to higher band. To address the above key issues, in this project, we propose a novel digital polarization power-combining method. In this method, a new scheme of divider, vector controller, frequency extender, amplifier and combiner in cascade is adopted, and the time or space symmetrical circular/sector waveguide high-order mode is chosen as the combined-wave mode. The digital polarization synthesis theory and technique will be researched, the key techniques, like vector calibration, error estimation, high-order mode radial combining and balanced mode converting, will also be broken through. Then, higher combining-efficiency and new functions (manipulation of the mode type and polarization direction) will be achieved. The results of the project have great significance for developing the power-combining technology and the system-development at high millimeter wave region.

功率合成可以倍增单个放大器的输出功率能力，在雷达、通信、成像、测量等领域有着重要的应用价值，是开发毫米波高端频段的关键技术。然而长期以来由于采用分配-放大-合成的构架和对主模合成的热衷，功率合成放大器存在合成效率无法软件优化、合成波模式和极化方向均不可实时控制、合成结构在更高频段难以实现等问题。针对上述关键问题，本项目提出了新颖的数字极化功率合成思路，采用分配-矢量控制-扩频/放大-反馈-合成的构架，选择具有时间或空间对称性的圆/扇波导高次模作为合成波的模式。通过研究数字极化合成方法及理论，突破矢量校准与误差估计、高次模径向合成以及平衡模式变换等关键技术，实现更高的合成效率以及合成模式和极化方向的可操控等新功能，对功率合成技术本身的发展和毫米波高端频段的系统开发有着重要作用和意义。

功率合成是倍增加单个放大器的输出功率能力的首要手段。本项目提出了圆波导圆极化模和扇形波导的角向对称模，更加适用于毫米波高频段；提出了数字极化功率合成方法，采用幅相控制-放大-合成的构架，利用矢量调制技术合成支路的幅相优化，在E波段（84~85 GHz）频段实现了最高91 %的合成效率；利用数字极化技术还实现圆极化旋向的可控和线极化波极化方向的可控；最后研究了基于平衡模式激励的模式转换器作为数字合成与标准矩形波导之间的接口。本项目提出的新方法在提高毫米波功率合成效率和实现空间电磁场的极化特性和模式类型上方面取得了良好的效果。