DESIGN OF A COMPACT ULTRAWIDEBAND METAMATERIAL ANTENNA BASED ON THE MODIFIED SPLIT-RING RESONATOR AND CAPACITIVELY LOADED STRIPS UNIT CELL

A a new compact ultrawideband (UWB) patch antenna based on the resonance mechanism of a composite right/left-handed (CRLH) transmission line (TL) is proposed. The radiating element of the antenna is made from three left-handed (LH) metamaterial (MTM) unit cells placed along one axis, where each unit cell combines a modified split-ring resonator (SRR) structure with capacitively loaded strips (CLS). An analysis of the eigenfrequencies of these unit cells yields one- and two-dimensional dispersion diagrams, which correspond to one-unit cell antenna and the three unit-cell antenna, respectively. A trident feed and a slotted-partial ground plane are used to match the right-and left-handed (RH and LH) modes of the antenna, respectively. In addition, an analysis of the surface current distribution of the antenna shows that, slots on the metallic area reduce the Q-factor. This recdution in the Q-factor results in a wide bandwidth of 189% at 3.7 GHz, which spans the UWB frequency range between 2.9-9.9 GHz. The total footprint of the antenna at the lowest frequency is 0.2λ0 x 0.2λ0 x 0.015λ0, where λ0 is the free space wavelength. The gain of the antenna ranges between -1 to 5 dB throughout the frequency band.