Metamaterial-Inspired Split Ring Monopole Antenna for WLAN Applications

This paper describes the design of a compact dual band monopole antenna for WLAN (2.4/5.2/5.8 GHz) applications. The antenna is printed on a 22.5x24x0.8 mm(3) FR-4 substrate with a partial ground plane and is fed by a microstrip line. The proposed structure consists of a simple hexagonal ring with a split arm along its center. The split in the arm in turn creates a quarter wavelength resonance in the higher frequency range. It also induces magnetic resonance which accounts for band notch between the WLAN lower (2.4 GHz) and upper bands (5.2/5.8 GHz). The extraction of negative permeability of the split ring structure is also discussed. A prototype of the proposed structure is fabricated and the measured results comply greatly with the simulated results. The antenna has consistent radiation pattern and stable gain over all the working region.