Circular patch microstrip antenna using an elliptical head dumbbell defected ground structure for WiMAX / Nur Rashidah Isnin

This thesis present the design of a circular patch microstrip antenna using an elliptical head dumbbell defected ground structure (DGS). The miniature circular patch antenna was simulated using Computer Simulation Technology (CST) Microwave Studio. The antenna was design to operate at 3.5 GHz and applicable for WiMAX (Worldwide Interoperability for Microwave access). A comparison is also presented for the antenna structure with defected ground and without defected ground. The parameters performances of the both antennas were analyzed and compared including size of microstrip. The performance of the proposed antenna was characterized by varying the geometry and dimension of the Defected Ground Structure (DGS) and also by locating the DGS at specific position which were simulated. Vector Network Analyzer (VNA) was used to measure both antennas and the results were compared with the simulation results. Return loss of -26.29 dB, Voltage Standing Wave Ratio (VSWR) of 1.102 and bandwidth of 3% is obtain from the defected ground structure. The size also reduces about 0.8 mm from the actual size.