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Conically scanning pencil-beam scatterometer systems, such as the recently launched Sea Winds radar, constitute an important class of instruments for spaceborne climate observation. In addition to ocean winds, scatterometer data are being applied to a wide range of land and cryospheric applications. A key issue for future scatterometer missions is improved spatial resolution. Pencil-beam scatterometers to date have been real-aperture systems where only range discrimination is used, resulting in a relatively coarse resolution of approximately 25 km. In this paper, the addition of Doppler discrimination techniques is proposed to meet the need for higher resolution. Here, the unique issues associated with the simultaneous application of range and Doppler processing to a conically scanning radar are addressed, and expressions for the theoretical measurement performance of such a system are derived. Important differences with side-looking imaging radars, which also may employ Doppler techniques, are highlighted. Conceptual design examples based on scatterometer missions of current interest are provided to illustrate this new high-resolution scatterometer approach. It is shown that spatial resolution of pencil-beam scatterometer systems can be improved by an order of magnitude by utilizing combined range/Doppler discrimination techniques, while maintaining the wide-swath and constant incidence angle needed for many geophysical measurements. Index Terms--Ocean winds, radar, backscatter.

This paper presents the self-surveying technique for calibrating the antenna spacing, orientation, and phase errors in multiple receiver radar antenna arrays. Utilizing a set of source transmitters placed at known locations in the far-field of the array and measurements of the phase present at each antenna, the array's relative antenna locations and phase errors can be determined. The advantage of this technique is that the radar is used in its normal operating mode, providing an end-to-end calibration under true operational conditions. A self-survey calibration was performed with a meteor radar located at Sondre Stromfjord, Greenland, successfully mapping the array. The antenna positions were relatively close the expected locations, although the baselines were rotated approximately 5 [degrees] from the true cardinal directions. The majority of the phase error was introduced by the receivers.