Calibration techniques for very large arrays

GMR Research & Technology (GMR) proposes to develop real-time digital methods to compensate for analog distortions in large RF arrays. In particular we will address manifold distortions caused by geometry, electronic, and near-field distortions. In this phase of the SBIR effort we will develop this approach for X-band arrays of at least 16 by 16 elements with at least 500 MHz instantaneous bandwidth. Our method is expected to achieve an improvement of at least 15dB over all angles and all frequencies in the RMS errors introduced by these calibration distortions. We will use beam-forming null depth as one of our metrics to show these improvements. This approach will be equally applicable to planar arrays and conformal arrays GMR has a track record of successfully using novel proprietary digital techniques for mitigating analog and mixed signal based distortion for government systems. In particular we use such techniques to mitigate receiver distortions including nonlinear and channel mismatch errors. Here we extend our methods to include multi-channel mismatch errors in the form of very large RF arrays.