Back Radiation Reduction in a UWB Antenna using Metamaterial Surface for Wireless Communication Devices

In this a 3*3 array of dual band AMC cells having dimensions of 15*15 is designed to reduce the backward radiations of a UWB antenna of size 35.5*33 . Each slot on the unit cell plays a key role in modelling the two desired frequencies of 4.7 and 9.9 GHz. The proposed AMC structure consists of a square patch loaded with a concentric ring and plus shaped slot in the center. The AMC behavior i.e. zero reflection phase point is observed at 4.7 and 9.9 GHz. The designed AMC structure is used as a reflecting layer to enhance forward radiations and thus reducing the backward radiations. Both structures (UWB antenna and dual band AMC structure) used FR-4 material with dielectric constant 4.4 and thickness 1.6 mm. As the designed UWB antenna already has satisfactory bandwidth (14.5 GHz) and gain (8.2 dB) values, therefore focus is given to reduce the back radiations of proposed antenna by using grounded AMC structure. The array size is fixed to be 3*3 whereas the air gap (d) between the two structures is varied and its corresponding effect on antenna results is studied. The proposed antenna is designed and simulated using computer simulation technology (CST) microwave simulation software.