Study on the main performances of interferometric radiometers with a rotating array

When observing unchanging targets or slow-changing targets, a rotating array can be used instead of a stationary array in an interferometric radiometer to reduce the complexity and the cost. The configuration of a stationary array determines its coverage in spatial frequency domain. But for a rotating array, the baselines were distributing on a series of concentric circles with radiuses of the baseline lengths, no matter what its configuration was. According to the characteristics of the distribution of the baselines, the expressions of system sensitivity and spatial resolution of a rotating interferometric radiometer were deduced in thwas paper. For a rotating interferometric radiometer with big synthetic aperture, like the Geostationary Interferometric Microwave Sounding (GIMS) prototype, it was very difficult to find a suitable calibration source to measure the system sensitivity. Therefore, the system sensitivity of the GIMS prototype was estimated based on the sensitivity of all channels by the sensitivity formula. Since the array factor of an interferometric radiometer was the pulse response of a point target, the spatial resolution of the GIMS prototype obtained by imaging an artificial quasi point target was used to demonstrate the formula in this paper, and the results were nearly identical. In addition, some different window functions were used to weight visibility samples of the prototype, and their effects on the sensitivity and the spatial resolution were analyzed. The principle of selecting the weighted window was described at the end.