Osama M. Haraz, and Abdel-Razik Sebak. “Novel UWB Trapezoidal and Butterfly Shaped Microstrip Phase Shifters Using Multilayered PCB Technology”. Applied Computational Electromagnetics Society Journal (ACES), vol. 31, no. 11, Aug. 2021, pp. 1309-14, https://journals.riverpublishers.com/index.php/ACES/article/view/9833.