Compact antenna based on a composite right/left-handed transmission line

This letter presents a novel antenna that is based on composite right/left-handed (CRLH) transmission line unit-cells implemented using slots and spiral inductors that are etched directly on the dielectric substrate by standard manufacturing techniques. The antenna is designed to operate across 5.8-7.3 GHz, which corresponds to a fractional bandwidth of 23%. Measured results confirm the antenna exhibits a relatively wide bandwidth, high gain, and high radiation efficiency characteristics. The measured radiation gain, bandwidth, and efficiency of the antenna at 6.6 GHz are 4.8 dBi, 23%, and 78%, respectively. The fabricated antenna is highly compact and its physical size in terms of the free-space wavelength is 0.39λ₀ × 0.13λ₀ × 0.015λ₀.