针对机载微带有源阵列天线单元间的互耦问题,提出了一种基于特征模理论的降耦方法。首先,通过分析天线单元被激励起的特征模式,筛选出工作模式和非工作模式;然后,根据阵列的结构、非工作模式的模式权重系数和特征远场方向图,分析出频带内对互耦贡献大的非工作模式;最后,通过抑制这些模式实现互耦降低,同时减少对工作模式的影响以保证天线性能。设计了频带为2. 19 GHz~2. 32 GHz 的微带天线单元,通过对贴片修形、设置金属柱等措施抑制频带内对互耦贡献大的非工作模式。将改进前后的单元组成微带二元阵进行仿真,结果表明:改进后的二元阵,在整个频带内的S21 降低了3 dB 以上、增益损失可接受、交叉极化得到改善。该方法为机载大型微带有源阵列天线的有效降耦提供了一条新思路。

To solve the mutual coupling of the airborne microstrip active array antenna, a decoupling method based on characteristic mode analysis is proposed. In this method, the excited characteristic modes of the element are studied to distinguish between working and non-working modes firstly. Then, non-working modes contributing more to mutual coupling are obtained by studying the structure of the array, modal weighting coefficients, and modal characteristic far fields. Finally, non-working modes are suppressed while reducing the impact on working modes, thereby reducing the coupling while ensuring antenna performance. A microstrip antenna element of the band of 2. 19 GHz to 2. 32 GHz is designed. Non-working modes contributing more to mutual coupling are suppressed by shaping the patch of the element and adding metal columns in the element. Binary arrays before and after the improvement are compared. It can be seen that S12 in the entire band is reduced by more than 3 dB with acceptable gain drop and improvement of cross polarization. This method provides a new idea for effective decoupling of the airborne large-scale microstrip active array antenna.

TN95

国家自然科学基金资助项目(61890544,91748106)