Miniaturized and Multiband Operations of Inset Feed Microstrip Patch Antenna by Using Novel Shape of Defect Ground Structure (DGS) in Wireless Applications

Microstrip patch antenna (MPA) with inset feed has been studied extensively over the past two decades because of its advantages. However, length of MPA is comparable to half wavelength with single resonant frequency with bandwidth around 2%. Electromagnetic bandgap (EBG) structure as defected ground structure (DGS) is proposed in this paper, so that signiflcant improvement in antenna size reduction and multi-band resonant frequencies operation are achieved. Two novel shapes of DGS are investigated. First, DGS is comparable to the flrst iteration of a fractal carpet concept. Second one is composed of four arms of a spiral shape. More than 45% reduction in size is achieved in the flrst shape. While second shape is two cells of spiral-shaped with four arms are used in the design. Simulation results show that more than 50% reduction in size was achieved as well as flves 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 4dB are achieved. The band-gap characteristics of the DGS are explained by using high frequency structure simulator HFSS R ∞ .