“…In particular, a frequency reconfigurable antenna is beneficial for various applications. Frequency reconfigurability can be achieved by using electrical switches [ 9 , 10 , 11 ], varactor diodes [ 12 , 13 , 14 , 15 ], p-i-n diodes [ 16 , 17 , 18 , 19 ], and radio-frequency micro-electromechanical systems (RF-MEMS) [ 20 , 21 , 22 ]. The electric switching technique has the advantage of lower voltage requirements, whereas RF-MEMS provide higher switching time.…”