A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D converter at a frequency well below L-band. Overall stability has been a design driver, as the instrument is intended for airborne measurements of polarimetric sea signatures.A novel L-band radiometer trading analog components for digital circuits has been designed, built and operated. It is a fully polarimetric radiometer of the correlation type, and it is based on the subharmonic sampling principle in which the L-band signal is directly sampled by a fast A to D converter at a frequency well below L-band. Overall stability has been a design driver, as the instrument is intended for airborne measurements of polarimetric sea signatures