Transmission line mode analysis of wideband/multiband antennas consisting of coupled conductors

Transmission line mode theory is used to analyze wideband/multiband small antennas consisting of several conductors. First, the modal theory is introduced with equations in order to implement the theory to antenna analysis. Eigenvalue and eigenvector matrices generated by the theoretical calculation are shown. As an example of simple analysis, ILA with a folded structure consisting of two-wire (FILA) is analyzed, and the validation of the theory is discussed. A circuit model of the FILA is used to obtain the impedance characteristics, and the relationship between the FILA and the modal theory is explained. Finally, a dual-band FILA is designed and the impedance characteristics calculated by the modal theory and simulation is compared.