Bandwidth bounds for small dipole antennas based on spherical wave scattering

For lossless, electrically small dipole antennas, the impedance matching bandwidth upper bounds are derived based on spherical wave scattering by the antenna in the low-frequency limit. The antenna is represented as a lossless matching network between the antenna port and the dominant TM₀₁ spherical wave port. The classical Fano approach is taken to derive integral identities for the magnitude of the antenna port reflection coefficient and bandwidth upper bounds. Unlike previously known Fano-type bounds, the new bandwidth bounds incorporate the effect of antenna details via the low-frequency electric polarizability.