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.