We are always surrounded by electromagnetic waves and fields of various spectra. This book explains basic electromagnetic theory with the help of design formulations i.e. mathematical background on antennas along with experimentations, which has made this book unique. The main purpose of this book is to embed mathematical EM theory of dielectric resonator antennas with experimental validation so that understanding of concepts takes place. Initially, basic understanding of philosophy of dielectric resonators has been discussed, then it is supported with mathematical modeling and later same is implemented with its prototype model along with experimentations. The modes theory gives important analysis on currents distribution, impedance analysis and radiation pattern in DRA. Circular polarization can built signal robustness, case studies on circular polarization has been included. Equivalent RLC circuit concept has been introduced. Challenges of switching from microwave to terahertz has been briefly discussed. Nano DRA will revolutionize the wireless technology. Nano DRA ,Terahertz DRA and Quantum DRA have analyzed and studied.