A technique for converting a wide-band coplanar waveguide fed antenna to UWB by positioning slots in the modified ground plane (MGP) adjacent to the feed is proposed in this paper. The slots can be symmetrically or asymmetrically positioned for optimum performance. One slot pair is initially positioned through parametric analysis in the modified ground plane at an equal distance from the feed end for the maximum achievable impedance bandwidth. The second slot pair is similarly positioned, optimising the antenna for ultra wideband operation. Two CPW fed antenna geometries are experimented using the technique, one unique and the other, a generic circular monopole. Both antennas have MGP and are fabricated on an FR4 substrate. The analysis and simulation have been done in FEM based High Frequency Structure Simulator (HFSS). The performance of the two antennas is measured with a Vector Network Analyzer ‘Agilent PNAE8362B'. The impedance bandwidth and radiation pattern validate the performance of the antennas for ultra wideband applications. The experimentally obtained bandwidth precisely covers UWB, and principal patterns are uniform throughout the band.
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