On Antenna Polarization Axes in L-Band Aperture Synthesis Arrays With Dual Polarization Receivers for Earth Observation

This reviews the choice of polarization axes in aperture synthesis arrays for remote sensing of the Earth, in particular when using dual polarization receivers. In this case, it is shown that there is the freedom of adopting rotated polarization axes across the array without signal loss. This is not possible in systems having dual-polarized antennas connected to single-channel receivers, and then, polarization time multiplexing requires the same antenna polarization at any time in all elements of the array if the signal loss is to be avoided. The flexibility allowed by the first type of instrument leads to a simpler antenna design and system architecture, providing a clear advantage over other polarization schemes. The review of the choice of the polarization axes is performed in the frame of the development of an advanced antenna for a future L-band aperture synthesis radiometer, but the analysis is general and applicable to any instrument of this kind. This is a study undertaken by the European Space Agency aiming at a possible future high-resolution follow-on mission to the currently flying Soil Moisture and Ocean Salinity (SMOS) mission.