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A theoretical framework for a mixed differential and common mode sensitivity analysis of active receiving antennas is presented, which includes the derivation of a novel set of noise parameters for dual-mode balanced amplifiers. The analysis is applied to an example of a mixed-mode active wire antenna design, consisting of an integrated monopole and dipole structure. Results of numerical simulations and experimental measurements are presented which show that, for a single-polarized design, the judicious use of both differential and common modes enables the field-of-view coverage to be extended over the entire hemisphere with a variation in receiving sensitivity of less than 3dB in the E-plane.

The polarimetric performance of a quad-mode antenna element, consisting of a pair of crossed dipoles and an integrated monopole fed by a quadraxial transmission line, is analysed. Results are compared to a conventional dual-polarised antenna consisting of two orthogonal dipoles. The presented study shows that the quad-mode antenna effectively doubles the polarimetric capabilities of a dual-polarised antenna over the hemispherical field of view.

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