Boadband tuning limits on UWB antennas based on Fano´s formulation

The well-known limits on the radiation Q of electrically-small antennas do not lead to a straightforward, rigorous computation of wideband impedance matching limits, especially when higher-order spherical modes are used and higher-order tuning networks are permitted. Fano´s formulation of the wideband matching of arbitrary impedances does provide a rigorous solution, and has been previously applied to the lowest-order (TM₀₁ or TE₀₁) mode. In this paper we apply Fano´s theory to higher-order spherical modes. Graphs of numerical limits on the in-band reflection coefficient tolerance versus electrical size for high-pass and band-pass tuning are presented