Investigations on co-planar waveguide fed pentagon shape planar monopole ultra-wide bandwidth (UWB) antenna on foam substrate providing invariant radiation patterns

It is well-established that the planar monopole antenna exhibits wideband impedance matching characteristics, high radiation efficiency, and an omni-directional pattern that makes it a desirable candidate for ultra-wideband (UWB) applications [1-2]. However, the radiation pattern deteriorates rapidly towards the high frequency end. Antennas fed with co-planar waveguides (CPW) have the further advantages of low dispersion for wideband applications, reduced radiation losses, and ease of fabrication [3]. Authors in [4] have demonstrated that the pentagon shape microstrip slot antenna shows an UWB impedance and radiation performance. Other authors in [5-6] have also investigated planar monopoles and techniques to improve the impedance bandwidth, but less emphasis has been placed on reducing pattern degradation over the band.