Annekaa, Ahmed, and Abdulgader Abdalla. “Design and Implementation of Closely Spaced MIMO Antennas Zeroth-Order Resonator Antenna (ZORA) With Enhancement Isolation”. Journal of Electrical and Electronic Engineering and Information Technology, vol. 1, no. 1, July 2020, pp. 44-48, https://jeeeit.com/index.php/jeeeit/article/view/26.