Band-Selectively Tunable Electromagnetic Bandgap Structures With Open-Circuit Lines and Variable Capacitors

We discuss the band-selective tuning of specific bandgaps (BGs) in an electromagnetic BG (EBG) structure. Two variable capacitors (VCs) attached to an open-circuit line (an element of the EBG structure) are selectively excited by voltage standing waves in the open-circuit line, and they can selectively tune the first and second BGs. With the change in a VC by 4.8 pF, the first BG moves from 0.55 to 0.39 GHz with almost no shift of the second one, while the second BG is tuned from 1.61 to 1.29 GHz with a 1.8-pF change in the other VC. This tuning technique can be potentially applied to other microwave devices using resonant phenomena such as antennas and filters.