“…An electrically small loop, used as the sensing part for the magnetic-field sensor, can respond positively to the magnetic-field component oriented normally to the surface of the loop [9,10,11]. An open-ended monopole can be employed to pick up the normal electric field [12,13,14,15], while the electrically small electric dipole is utilized to detect the tangential electric field [16,17,18] over a surface above the planar circuit. The electromagnetic sensors can effectively sense electromagnetic fields so that there has been increasing attention given to developing high-performance electric-/magnetic-field sensors, such as extending the bandwidth [19,20,21], improving the spatial resolution [22,23,24] and enhancing the sensitivity [25,26,27,28].…”