Miniaturised planar-patch antenna based on metamaterial L-shaped unit-cells for broadband portable microwave devices and multiband wireless communication systems

This study describes the design of a metamaterial planar antenna for multi-octave band operation. The metamaterial unit-cell comprises L-shaped slit which is etched inside a rectangular patch with a grounded inductive spiral. The slit essentially behaves as a series left-handed capacitance and the spiral as a shunt left-handed inductance. The antenna was modelled and optimised for impedance bandwidth, gain and efficiency performance using commercial three-dimensional full-wave electromagnetic simulation tools. The antenna has a measured impedance bandwidth of 6.02GHz for S-11<-10dB. This corresponds to a fractional bandwidth of 172.49%, which is higher than multiband planar antennas reported to date. The antenna has a maximum gain and efficiency performance of 3.7dBi and 73%, respectively, at 3.25GHz. The physical footprint of the antenna is comparable to other wideband planar antennas reported to date. The overall size of the antenna is 0.037(0)x0.027(0)x0.002(0) and 0.25(0)x0.18(0)x0.017(0), where (0) is free-space wavelength at 0.48 and 3.25GHz, respectively.