Omnidirectional UWB Antenna Loaded with Rectangular Loop for Band Notch Characteristics

An omnidirectional planar UWB antenna and its 2×2 MIMO antenna version are presented. The antenna achieves band-notch characteristics owing to the loading of a rectangular microstrip loop inside the radiator. Simulation results of the proposed antenna yield a bandwidth from 3.06-15.34 GHz offering a notched band from 4.13-5.38 GHz. The variation observed in the simulated group delay is found to be smaller than 1 ns satisfying the criterion for dispersion free communication. With omnidirectional radiation patterns, the proposed antenna achieves a maximum radiation efficiency of 95%. Moreover, a 2×2 MIMO antenna composed of two UWB antenna elements placed orthogonally is designed and its diversity characteristics are investigated in terms of isolation, envelope correlation coefficient, diversity gain and multiplexing efficiency. The proposed UWB antenna is geometrically planar and compact, having a dimension of 30×30×1.52 mm
³
that can be integrated in portable UWB devices.