Analytical characteristic expression for dualband antennas embedded with elements inside the antenna

An analytical expression for current distribution, input impedance, and radiation power including higher order modes, is derived for a thin sectorial antenna embedded with lumped and distributed elements. To obtain the formulae, radiation power is analyzed in two ways using Chu´s equivalent circuit and the multipole expansion method. By numerical estimation of the formulae for electrically small antennas with the elements, dualband antennas are shown to be realized. The dualband antennas are fabricated, and measured input impedances agree well with the calculated data. Measured radiation patterns are omni-directional in the H-plane and the figure-of-eight in the E-plane for both the bands.