Compared with many similar books in the field of metamaterial/artificial electromagnetic structures (AESs), this book takes the theoretical analysis and design implementation of AES-based multi-functional antennas (MFAs) as the breakthrough point. It covers a variety of MFAs, such as mushroom- structure-based MFAs, artificial magnetic conductor (AMC)-based MFAs, compact MFAs, broadband MFAs, end-fire MFAs and so on. It greatly expands the antenna styles and enriches the application examples of AES antennas, which has important values on theoretical research and engineering application.