DESIGN OF A MULTI-BAND MIMO ANTENNA FOR MOBILE APPLICATION

Abstract

In this thesis, a multi-band MIMO antenna using a modified neutralization technique is proposed. With the recent development of wireless communication technology, MIMO system is one of the effective ways for improving reliability and increasing the capacity of the channel. The capacity of a wireless channel is affected by the mutual coupling between antenna elements. Since the antenna elements are placed close to each other on the common ground, the mutual coupling between them is strong enough to excite additional surface current distribution on the ground. A modified neutralization technique is used to reduce the surface current induced on the common ground and improve the isolation characteristic. The proposed MIMO antenna is designed to operate at LTE, WiBro, WLAN and M-WiMax services. Each antenna element is designed on the folded monopole structure. By adjusting the feeding stub length, edge length and stub size, the designed antenna can satisfy the performance requirements over the frequency band of interest. To achieve the high isolation characteristic, a modified neutralization technique is used. In a modified neutralization technique, a neutralization line and a resister are used. By choosing the proper resistance value in a modified neutralization line, the isolation characteristic is satisfied over the required frequency band.