Antenna Insertion Phase Variation With Polarization and Methods for Compensation

A fundamental analytical description is given for antenna insertion phase variation with polarization and is demonstrated through interferometer measurements of several Ka-band antenna elements. Detailed knowledge of the antenna phase variation is critical for high fidelity angle measurement in interferometer and phase comparison monopulse systems where two antennas may not have identical phase response to varying polarization. Detailed derivation of the phase variation is obtained by preserving the argument of the normalized complex voltage. Antennas with different polarization properties are shown to have different phase responses to incident wave polarization orientation which can produce significant spatial angle errors. The analytical development presented here can be used to specify antenna polarization properties during design to ensure tolerable error performance. Alternatively, compensation for the phase variation can be implemented in real-time using the analytical expressions and knowledge of the incident wave polarization properties.