A Compact Hexagonal Wide-Slot Antenna With Microstrip-Fed Monopole for UWB Application

This is a presentation of a compact wide-slot antenna with microstrip-fed monopole for ultrawideband (UWB) application. The monopole is composed of an elliptic patch connected to a trapezoid one. The radiator patch is attached to a 50-Ω microstrip feed line by a smoothly tapered line to enhance the wideband matching. A hexagonal slot is etched from a finite ground plane placed on the other side of the substrate. The antenna has compact physical structure and is designed on standard FR4 substrate. Simulation and optimization with Ansoft HFSS and CST Microwave Studio software indicate 145% fractional impedance bandwidth varying from 2.9 to 18 GHz for VSWR less than 2. The antenna is successfully fabricated and characterized by measuring VSWR, radiation pattern, and gain. Comparison between simulated and experimental results exhibits a near agreement in the operating band. In addition, it yields an average gain of several decibels with low tolerance and reasonable stable radiation characteristics. The effects of vital parameters on antenna performance and some other details are analyzed and discussed as well.