A compact highly isolated two ports microstrip antenna based on Defected Ground Structure for WLAN/WiMAX applications

Strong mutual coupling between closely spaced ports in compact antenna has been caused significant system performance degradation, such as reduction in gain and signal-to-noise ratio. In this paper, an efficient technique utilizing the Defected Ground Structure (DGS) has been employed to propose two-port Elliptical patch structure. The proposed DGS has been used to control and separate the resonant frequency of each port and reduce the coupling effect. The presented two-port antenna structure has been analyzed, investigated and optimized using Finite Integral Technique (FIT) numerical method. The designed antenna has a small overall size of 30 × 30mm², and operates over the frequency ranges, 5.7-5.97 GHz, and 5.35-5.6 GHz suitable for WLAN and WiMAX applications. The first port operates at 5.8 GHz with efficiency 62% while second port operates at 5.43 GHz with efficiency 66%. Thus, the proposed DGS is simply representing built-in resonance and decoupling circuits with no additional cost. In addition, maximum VSWR value <; 1.5 have been achieved through the operating frequency range. The presented DGS pattern has been proved to be an excellent feature for designing and optimizing any two-port antenna configuration. Moreover, the proposed two-port microstrip antenna with separated resonance frequencies can be used as multifunction antenna in several communication applications. Good agreement has been obtained between simulated and measured parameters.