Orugu, Rangarao., Srilatha. Gundapaneni, N Maryleena, and A K.Chaithanya Varma. “Varying Operating Frequency of Concentric Circular Ring Patch Antenna Using High Impedance Surface”. International Journal of Engineering and Technology 7, no. 3.29 (August 24, 2018): 57–60. Accessed August 17, 2025. https://mail.sciencepubco.com/index.php/IJET/article/view/18461.