James A. Quinlan, and Daniel N. Aloi. “Ground-Based Augmentation System Antenna Array Size Reduction via Self-Cardioid Element”. Applied Computational Electromagnetics Society Journal (ACES), vol. 35, no. 10, Oct. 2020, pp. 1228-35, https://journals.riverpublishers.com/index.php/ACES/article/view/7693.