Evaluation of total antenna (Q) in terms of the Qn of modes provided by theory of characteristic modes

Summary form only given. The study of the antenna Quality factor (Q) has been an active topic of research for a long time. Its importance is directly related to its connection to the antenna frequency bandwidth. Many authors have discussed the problem of formulating the Q of an antenna. Chu, Mclean, Wheeler, Gustafsson, Thal, Yaghjian, Harrington and Vandenbosch were among many whom studied the Q bounds of electrically small antenna (ESA) and Q in general. Several studies were taken from Chu sphere, employing scattering theory and applying quasi-static energy approximations to name few; however, these approaches require specific assumptions on polarization and absorption efficiency, and provide little insight into the type of excitation needed to realize an optimal Q.