A planar ultra-wideband monopole antenna with half-circular parasitic patches

A simple planar ultra-wideband (UWB) microstrip-fed antenna with defected ground structure and two parasitic patches is presented. Two symmetrical quarter-circle shaped segments are cut both on the each of lower edges of the radiating patch and on the each of upper edges of the ground plane. These segments provide a wider bandwidth than the ordinary rectangular antenna especially in the middle frequencies. By means of removing U-shaped slot in the radiating patch the radiation characteristics of the 7-10 GHz frequency range are improved. Two half-circle shaped parasitic patches are connected via a hole to the ground plane. These patches are added on both sides of the 50-Ω microstrip-fed line to achieve good radiation performance for frequencies higher than 10 GHz. The proposed antenna is simulated by ANSYS´s HFSS program using finite element method (FEM). The simulation results show that 127% of the impedance bandwidth is between 3.1 and 13.8 GHz for 20log|S11|<;-10 dB. The simulated antenna is fabricated on FR4 substrate and measured.