Development of circularly polarized Synthetic Aperture Radar onboard unmanned aerial vehicle

Synthetic Aperture Radar (SAR) is well-known as a multi-purpose sensor in all-weather and day-night time. In this research, we are developing Circularly Polarized Synthetic Aperture Radar (CP-SAR) onboard microsatellite to observe land deformation on Earth surface under Japanese Ministry of Education and Technology (MEXT) program etc. The CP-SAR employs elliptical wave propagation and scattering phenomenon by radiating and receiving the elliptically polarized wave, including the specific polarization as circular and linear polarizations. The sensor is designed as a low cost, light, low profile of configuration to transmit and receive left-handed circular polarization (LHCP) and right-handed circular polarization (RHCP). Then these circularly polarized waves are employed to investigate relationship of physical information of scatterer and axial ratio, ellipticity, tilt angle etc. This sensor is also considered to reduce the effect of ionosphere´s Faraday rotation. For ground experiment of CP-SAR, we also develop the CP-SAR onboard unmanned aerial vehicle (UAV CP-SAR) that is discussed in this paper.