Performance enhancement of small antennas using metamaterials —challenges and future directions

In this review paper we take a critical look at the problem of performance enhancement of small antennas using metamaterials. We first review the definitions of metamaterials that have been used in the literature, and then introduce our own classification of metamaterials in the microwave regime - that are artificial dielectrics - by dividing them into two broad sub-categories. Representative examples of antenna / metamaterial composites are presented and the paper concludes some thoughts on future directions of Metamaterial Research, focusing on the aspect of performance enhancement of small antennas.