In this work, a quad-band omnidirectional slot antenna array is proposed. The structure consists of two closely-spaced radiating elements fed using coplanar waveguide (CPW) line. This combined structure is then integrated in a tapered slot etched on the antenna to enable operation in four frequency bands (0.8, 1.8, 2.6 and 3.45 GHz) for LTE and WiMAX applications with at least -10 dB of reflection coefficient. The antenna dimensional parameters are also studied to understand its behaviour and eects on its performance in facilitating the optimization process. Measurements of the fabricated antenna on a low-cost FR4 substrate validate its operation centred at 0.845 (from 0.77 to 0.92 GHz), 1.74 (from 1.59 to 1.9 GHz), 2.655 (2.59 to 2.72 GHz) and 3.49 GHz (from 3.28 to 3.7 GHz). Meanwhile, simulated and measured radiation patterns of the proposed antenna in all bands agree well and are omnidirectional, making is suitable for application in mobile terminals.
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