Novel MIMO Antennas Based On The Metamaterials

With the rapid development of wireless communication,the multiple-input-multiple-output?MIMO?technology and metamaterials have become one of the hottest topics of antenna industry.Focusing on the topic of metamaterial-inspired MIMO antenna,the metamaterial-inspired ultra-wideband?UWB?antenna and novel decoupling structures have been studied.The main contents of this dissertation are as follows:1.Based on the traditional monopole antenna,we designed an UWB antenna.After analyzing the electromagnetic characteristics of a dual band complementary split ring resonator?CSRR?,we used it to enhance the band-notch performance of the proposed UWB antenna.Based on the proposed dual-band notch UWB antenna,we developed an UWB MIMO antenna.Since the mutual coupling of the UWB MIMO antenna is high in multiple bands,we proposed a novel decoupling split ring resonator?SRR?and use it to realize the high isolation(the S₂₁ parameter is under-20 dB)in whole operation band.2.We designed a compact wideband quad-element MIMO antenna.The proposed wideband antenna has an extremely wide operation band which covers from 2.9 GHz to30 GHz.Using the methods such as orthogonal polarization directions,reversing the antenna geometry to cut off the current path,introducing metamaterial unit cell,we successfully realize the high isolation?the transmission coefficient is under-18 dB?in such a wide operation band.After investigating the effect of antenna dimensions on the performance of the proposed monopole antenna by using the transmission line theory,the overall size of the proposed MIMO antenna has been largely reduced.Finally,we got a much smaller MIMO antenna with the similar radiation performance.3.We developed a compact wideband antenna which can operate from 2.2 GHz to32 GHz.Based on this compact wideband antenna,a quad-element MIMO antenna is developed.Since the mutual coupling of the proposed quad-element MIMO antenna is high from 2 GHz to 7 GHz and the distance between antenna elements is extremely narrow,we proposed a novel metamaterial decoupling wall structure.Compared with the traditional metamaterials,the proposed metamaterial decoupling wall structure can realize a wide operation band with a much smaller size.The proposed MIMO antenna can realize compact structure,low profile,high isolation.4.Based on the traditional SRR,we proposed a compact wideband millimeter antenna.Through introducing multiple reversed banches and parasite branches,the operation band of this compact wideband millimeter antenna ranges from 24 GHz to 36GHz.Based on it,a massive MIMO antenna is developed.Both the theoretical and simulated results show that this compact wideband millimeter MIMO antenna can realize high isolation?the transmission coefficient is under-20 dB?without introducing any extra decoupling structure.Besides,the simulation shows that the mutual coupling maintains under a pretty low level while changing the antenna element position.This fact implies that the geometry of the proposed MIMO antenna can be freely adjusted as required.