Comparison of the radiometric signatures of ore boats and their wakes at 35 GHz with model calculations

Vertically polarized antenna temperatures of ore boats and their wakes were measured with a 35-GHz radiometer from a helicopter platform. The signatures of the boats appear to be independent of viewing angle at a temperature which is about 40 K cooler than the surrounding water. The signatures of the wakes show a dependence on viewing angle. Models for the antenna temperature are presented which fit the measured data to within the accuracy of the measurement and model parameters. These models are useful in themselves for predicting the antenna temperatures of targets in terms of parameters such as viewing angle, beam fill factor (BFF), antenna main beam efficiency, and target emissivity.