Inductive slot-loaded composite right/left-handed transmission line and its application to bandwidth-improved resonant antenna

In this paper, a new composite right/left-handed transmission line (CRLH-TL) with inductive ground slots is proposed to improve an operating bandwidth for zeroth-order resonant antenna applications. From the equivalent circuit model of the inductive slot-loaded CRLH-TL (SL CRLH-TL) unit-cell, the characteristic impedance and the dispersive relation are derived. By adding inductors on the ground slots, each resonant frequency of the unit-cell has been decreased in adjacent zeroth-order and cavity modes. Finally, the 3.3-nH inductor loaded antenna yields neighbouring resonances. The measured 10-dB bandwidth of the proposed antenna is obtained 16.2 % compared with a bandwidth of 0.43 % in the antenna without inductors.