ABSTRACT
Design approaches to multi-mode resonant slot and loop antennas are dealt with in this chapter. Brief history of classical slot and loop antennas are illustrated. Multi-mode resonant design approaches to slotline antennas at the basic form are presented. Slit- and strip-loaded dual-mode resonant slotline antennas have been studied to validate the operational principle at first. Then, triple-mode resonant cases have been investigated to show the radiation dispersion controlling technique of wideband slotline antennas. Next, mode transition between slot and loop antennas is discussed to deduce the eigenmode theory of loop antennas. A pair of resonant, even-modes is employed to deduce the conceptual design of Poincaré source antenna, thus it leads to a series of circularly polarized loop antennas designs with bidirectional/unidirectional, balanced/unbalanced, wideband, and dual-band operations.
