Ultrawide Bandwidth (UWB) Planar Monopole Antenna Backed by Novel Pyramidal-Shaped Cavity Providing Directional Radiation Patterns

An ultrawideband (UWB) coplanar waveguide (CPW)-fed pentagon-shaped planar monopole antenna (PMA) backed by a novel pyramidal-shaped cavity is presented that provides directional radiation patterns. The pyramidal-shaped cavity reflector is placed at a fixed spacing from the UWB monopole antenna to provide impedance and radiation performance over 110% (3.1-10.6 GHz) frequency band. The PMA itself on a foam substrate provides stable gain variation within 3 dB over an impedance bandwidth (w.r.t. S₁₁ <; -10 dB) of 120% (3-12 GHz). The proposed cavity-backed PMA prototype antenna was fabricated, and experimental verification was performed for impedance matching and radiation patterns. The measured results show reasonable agreement with the simulated ones.