**5. Conclusions**

In this paper, considering that the GA representation contains physical interpretations and complete information of incident signals, we use the idea of the traditional ESPRIT algorithm to find multiple EM signals in the direction finding method in GA. In particular, the model for DPULAs was built in GA and GA-ESPRIT was successfully derived using new calculation rules to achieve the two-dimensional DOA estimation. Compared with the previous ESPRIT algorithms, due to the robustness to sensor-model error and correlated noise, our proposed approach has potential in many practical situations, such as military radar in difficult environments. According to the experimental results, we have confirmed that the GA-ESPRIT has improved accuracy in two-dimension DOA estimation and can resist environmental interference to some extent. More importantly, the proposed algorithm achieves a reduction of more than 1/3 of the memory requirements while the time complexity is also greatly decreased.

Future works on the GA-ESPRIT will include polarization parameter estimation by optimizing matrix operations in GA and the ability of DOA recognition when facing coherent EM signals. It is expected that the proposed GA-ESPRIT will be an efficient DOA estimator.

**Author Contributions:** Conceptualization, R.W. and W.C.; methodology, R.W. and Y.W.; software, Y.W.; data curation, Y.W. and Y.Y.; writing—original draft preparation, Y.W. and Y.L.; project administration and funding acquisition, R.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by National Natural Science Foundation of China (NSFC) under Grant No. 61771299, 61771322 and Shenzhen foundation for basic research JCYJ 20190808160815125.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
