Analytical expression of broadband characteristics for wide-angle planar sectorial antennas

Analytical expression of the characteristics for wide-angle planar sectorial antennas on a substrate is derived using the mode-expansion method, where higher-order modes for the φ orientation are included. With only eigenfunctions for θ, the mode expansion coefficients and input impedances are numerically estimated, and the broadband characteristics are shown to be realized for wide-angle antennas. Planar sectorial antennas with varied angles were fabricated on a FR-4 substrate, and the measured input impedances and measured radiation patterns agreed fairly well with the numerical data. However, for the wide-angle antenna, the measured radiation patterns at higher frequencies were the patterns for the higher-order mode for φ.