Tunable multiband antenna using ENG ZORs

We propose a tunable multiband antenna using four epsilon negative zeroth order resonators (ENG ZORs). Each ENG ZOR unit cell consists of two shunt inductors for the epsilon negative property, a transmission line for the right handed property, and a variable capacitor for wide frequency tuning range. ENG ZORs #1 and #2 are placed on the same ground plane and operated at Tx band (f
₁
) and Rx band (f
₂
) of lower band, respectively. In contrast, ENG ZORs #3 and #4 are constructed perpendicular to the ground plane and have the resonance frequencies at Tx band (f
₃
) and Rx band (f
₄
) of higher band, respectively. The resonant frequencies of the designed antenna can be tuned from 740 MHz to 940 MHz at lower band and from 1.545 GHz to 2.05 GHz at higher band. The designed antenna has the very compact size of 50 mm × 5 mm × 5 mm.