Abstract: As a new research frontier in electromagnetics (EM), surface electromagnetics (SEM) provides important theoretical guidelines for novel microwave and antenna devices. This paper presents a brief overview of surface electromagnetics, including development history, scientific importance, and critical research topics. Furthermore, a novel SEM-based design methodology is proposed for phased array antennas, and several examples are presented, including a micromotor-controlled phased array using rotatable EM surface, a super-large phased array (10 240 elements), a very high frequency phased array (96 GHz), and a transmission-type phased array, all using electronic-tunable EM surfaces. Finally, the proposed phased array is applied in a microwave/millimeter wave security imaging system, and experimental results demonstrate the feasibility and accuracy of the fast all-electronic space imaging system.