Design of planar monopole antenna for use of UWB application with DGS

This paper introduces a compact microstrip-based UWB monopole antenna developed to achieve wideband and efficient performance. The antenna has physical dimensions of 41 × 38 × 1.6 mm³, corresponding to an electrical size of 0.41λ × 0.38λ × 0.0016λ at 3 GHz. A modified rectangular radiator is used on the top layer, incorporating two lower-edge notches and a central square slot. These structural modifications increase the effective current path, improve impedance matching, and contribute to bandwidth enhancement. To further improve performance, a Defected Ground Structure (DGS) is implemented on the bottom layer, which suppresses surface currents, increases radiation efficiency, and stabilizes gain across the band. The proposed antenna achieves an impedance bandwidth ranging from 3.08 GHz to 10.38 GHz, corresponding to a 111% fractional bandwidth with a center frequency of 6.93 GHz. The gain reaches its highest value of 5.61 dBi at approximately 10.4 GHz, while the radiation efficiency remains consistently high between 86% and 96%. Compared to several recently reported UWB monopole designs, the designed antenna achieves a practical mix of small dimensions, broad operating bandwidth, strong efficiency, and consistent gain performance. These features indicate that the antenna can be effectively used in several UWB-oriented systems such as close-range sensing, imaging platforms, detection modules, and compact radar units.