Epsilon Negative CPW-Fed Zeroth-Order Resonating Antenna With Backed Ground Plane for Extended Bandwidth and Miniaturization

A compact CPW-fed metamaterial (MTM)-inspired zeroth-order resonating (ZOR) antenna is presented with backed ground plane. Such MTM antenna consists of thin conducting line and a bow-tie shaped patch connected to CPW feed. The proposed structure shows compact size with radiating element dimensions of 0.095λ_o × 0.042λ_o × 0.013λ_o by introducing ground plane at bottom. As an advantage, resonant frequency is shifted toward left which corresponds to 57.9% miniaturization area with respect to the proposed antenna without backed plane (resonating at 3.7 GHz). The proposed MTM antenna exhibits zeroth-order resonance (ZOR) at 2.4 GHz and has an impedance bandwidth (S11 <; -10 dB.) of 25.4%. The proposed structure shows good radiation characteristics with simulated absolute gain of 1.59 dBi and simulated radiation efficiency of 91.5% throughout the operating bandwidth. Now for extending the bandwidth and shifting the resonant frequency to be operated in WiMAX band (3.5-3.57 GHz), electromagnetic band gap (EBG) structures are loaded in upper ground plane. This antenna shows an impedance bandwidth of 54.2% and resonates at 3.3 GHz. The radiation patterns are consistent throughout the working band. The prototype structures have been fabricated and experimentally validated. The designed antennas are suitable for use in LTE, WLAN, and WiMAX (2.5/3.5 GHz).