A superdirective antenna array has the potential to achieve an array gain proportional to the square of the number of antennas, making it of great value for future wireless communications. However, designing the superdirective beamformer while considering the complicated mutual-coupling effect is a practical challenge. Moreover, the superdirective antenna array is highly sensitive to excitation errors, especially when the number of antennas is large or the antenna spacing is very small, necessitating demanding and precise control over excitations. To address these problems, we first propose a novel superdirective beamforming approach based on the embedded element pattern (EEP), which contains the coupling information. The closed-form solution to the beamforming vector and the corresponding directivity factor are derived. This method relies on the beam coupling factors (BCFs) between the antennas, which are provided in closed form. To address the high sensitivity problem, we formulate a constrained optimization problem and propose an EEP-aided orthogonal complement-based robust beamforming (EEP-OCRB) algorithm. Full-wave simulation results validate our proposed methods. Finally, we build a prototype of a 5-dipole superdirective antenna array and conduct real-world experiments. The measurement results demonstrate the realization of the superdirectivity with our EEP-based method, as well as the robustness of the proposed EEP-OCRB algorithm to excitation errors.

翻译：超指向性天线阵列具有实现与天线数量平方成正比的阵列增益的潜力，使其对未来无线通信具有重要意义。然而，在考虑复杂互耦效应的情况下设计超指向性波束赋形器是一项实际挑战。此外，超指向性天线阵列对激励误差高度敏感，尤其是在天线数量较多或天线间距极小时，这需要对激励进行严苛而精确的控制。为解决这些问题，我们首先提出了一种基于嵌入式单元模式（EEP）的新型超指向性波束赋形方法，该方法包含了耦合信息。推导了波束赋形向量及相应方向性系数的闭式解。该方法依赖于天线间的波束耦合因子（BCF），并以闭式形式给出。针对高敏感性问题，我们构建了一个约束优化问题，并提出了一种基于EEP辅助的正交补鲁棒波束赋形（EEP-OCRB）算法。全波仿真结果验证了所提方法的有效性。最后，我们构建了5偶极子超指向性天线阵列原型并进行了实际实验。测量结果表明，基于EEP的方法实现了超指向性，且所提EEP-OCRB算法对激励误差具有鲁棒性。