22 - 26 April 2019
Westin Waterfront Hotel
Boston, Massachusetts USA

Tutorial: Adaptive Arrays: Principles and Applications

22 April Monday Morning Session 11:00 AM – 3:00 PM

Prof. Randy L. Haupt
Electrical Engineering & Computer Science
Colorado School of Mines

Dr. Mark C. Leifer
Staff Consultant and Chief Engineer
Ball Aerospace

This course describes the antenna technology (arrays, low sidelobe-, high directivity-, and reconfigurable antennas) and signal processing algorithms that are used in modern radar systems to reject interference. Particular emphasis is placed in this tutorial on an intuitive understanding of array operation and of the interference nulling process. Numerous adaptive techniques, most of which seek to optimize SINR (the ratio of signal to interference-plus-noise), are available to the system designer. They offer differing levels of complexity and performance. Attendees will survey these techniques and learn both the practical and mathematical aspects of their use. The course begins by reviewing the basics of antenna arrays and beamforming, establishing a firm context for the introduction of array-based adaptive algorithms. A simplified and practical explanation of the array covariance matrix with its eigenvalues and eigenvectors is presented, together with an understanding of their role in adaptive nulling. Classic covariance matrix-based approaches are introduced next, including the LMS gradient-based algorithm and the LS and MVDR block processing algorithms. Intuitive graphical explanations of beamforming and nulling will accompany mathematical descriptions of how the algorithms work. Guidance on which algorithms are best in specific applications will be presented, providing valuable practical information that is often missing from conference tutorials. The remainder of the course covers specialty techniques useful for large arrays, such as sidelobe cancellation and partially adaptive arrays, as well as non-digital techniques such as reconfigurable arrays. This short course is broken into four parts: (1) Fundamentals—arrays, signals, terminology, beamforming, null synthesis (2) Introduction to adaptive nulling—digital beamforming and non-digital beamforming approaches, reconfigurable arrays, an intuitive introduction to eigenvalues and eigenvectors of the covariance matrix, array calibration (3) Covariance-based algorithms—least squares, MVDR, LMS and Howells-Applebaum nullers, and their relations to each other (4) Implementation details and practicalities—block processing methods, iterative methods, diagonal loading, sub-optimal methods (subarray-level beamforming, e.g.), guidance on which methods to use for which applications