Advanced Metrology Technologies for Next-Generation Space-Based Radar

Space-based radar concepts employing large (~ 300 m length) semi-rigid, active phased array antennas are being investigated for surveillance missions that include detecting surface moving targets in severe clutter environments. To achieve the required transmit and receive antenna pattern characteristics, metrology concepts are needed to address aggregate phase errors from structural, electronic and propagation sources. These error sources degrade the knowledge of the relative phase between sub-panels thereby producing an ineffective antenna pattern and poor beam pointing control. Technology Service Corporation and BBN Technologies will develop innovative techniques to isolate the phase and differential range errors. Our layered metrology concept utilizes miniaturized electronics already designed into the waveform generation and reference signal paths and that are distributed in the antenna. In Phase 1, a dedicated radar antenna calibration mode will be formulated for a candidate payload design to develop mission performance models and orbital demonstrations. Feasibility studies of how observations can be made both locally and in the far-field of the antenna to support the calibration will also be conducted. Novel orthogonal waveforms to support calibration will also be investigated by our team. In Phase 2, TSC and BBN will implement a metrology concept that is compatible with emerging AESA designs for Air Force SBR programs.