A novel UWB antenna with good characteristics for microwave imaging system

In this paper, a novel UWB antenna with good characteristics for microwave imaging system is represented. The antenna is printed on an FR4 substrate of thickness 1.6 mm and permittivity 4.4. The antenna is fed by a CPW line which is designed for 50 Ohm characteristic impedance. The antenna structure is composed of a circular radiating element, a micro-strip transmission line and a defected ground structure which provides a wide band width. By tuning the parameters of the defected ground structure, the proposed UWB antenna can cover from 2.7GHz to 13.8GHz frequency with a VSWR less than 2 and return loss less than -10. It is promising in microwave imaging systems due to its wider bandwidth, better VSWR response, lower return loss and better surface current distribution for using in microwave image field.