Multiband and miniaturized inset feed microstrip patch antenna using multiple spiral-shaped defect ground structure (DGS)

Microstrip patch antennas with inset feed have been studied extensively over the past two decades because of its practical advantage when used in mobile wireless systems. The length of MPA, however, is comparable to a half wavelength with single resonant frequency and bandwidth around 2%. In this paper, we describe a novel approach to reduce the antenna size and provide multiband operation. Electromagnetic bandgap (EBG) structure is used as defect ground plane structure to reduce size and achieve multiband resonant frequencies. Two cells of spiral-shaped defected ground structure (DGS) with each cell composed of spiral with four arms are used in the design. Simulation results show that more than 50% reduction in size was achieved as well as fives resonant frequencies resulted from the new design. One resonance resulted from the fundamental patch antenna while the other four resulted from each spiral arms. Acceptable E-plane and H-plane radiation patterns and an antenna gain of about 4 dB are achieved.