In recent years,metamaterial has broken physical limitations of traditional materials and structures,which would bring new development of high-efficiency transmitting antennas.It has got more and more attentions.In this paper,the research overview of the theory and structure of metamaterial have been introduced at first.Furthermore,the researches of several novel metamaterial technologies on improving the efficiency of planar antenna elements are specifically given and analyzed,including non-periodic metamaterial technology,metamaterial as novel radiation elements or low-profile reflection plane,etc.Finally,aiming at the requirement of wireless energy harvesting on high-efficiency antenna array,excitations using high-order modes and novel low-loss transmission lines have been introduced for low-loss feeding networks of antenna arrays and higher system efficiency.