- S. Unnikrishna Pillai, "A MAP Estimate that Maximizes Entropy - An Alternative Interpretation for an Auto Regressive Model," Proceedings of IEEE, Vol. 73, No. 4, pp. 843-844, April 1985.
- S. Unnikrishna Pillai, Y. Bar-Ness and F. Haber, "A New Approach to Array Geometry for Improved Spatial Spectrum Estimation," Proceedings of IEEE, Vol. 73, No. 10, pp. 1522-1524, October 1985.
- S. Unnikrishna Pillai and Fred Haber, "Statistical Analysis of a High Resolution Spatial Spectrum Estimator Utilizing an Augmented Covariance Matrix," IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-35, No. 11, pp. 1517-1523, November 1987.
- S. Unnikrishna Pillai and B. H. Kwon, "Forward/Backward Spatial Smoothing Techniques for Coherent Signal Classification," IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-37, No. 1, pp.8-15, January 1989.
- S. Unnikrishna Pillai, and Y. J. Lee, "Coherent Signal Classification Using Symmetry Considerations," IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-37, No. 1, pp. 135-138, January 1989.
- Dante C. Youla and S. Unnikrishna Pillai, "A Uniqueness characterization in Terms of Signed-Magnitude for Functions in the Polydisc Algebra," Journal of Optical Society of America, Vol. 6, No. 6, pp. 859-862, June 1989.
- B. H. Kwon and S. Unnikrishna Pillai,"A Self Inversive Array Processing Scheme for Angle-of-Arrival Estimation," European Signal Processing Journal, Vol. 17, No. 3, pp. 259-277, July 1989.
- S. Unnikrishna Pillai and B. H. Kwon, "Performance Analysis of MUSIC-Type High Resolution Estimators for Direction Finding in Correlated and Coherent Scenes," IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-37, No. 8, pp. 1176-1189, August, 1989.
- D. Pearson, S. Unnikrishna Pillai, and Y. J. Lee, "An Algorithm for Near-Optimal Placement of Sensor Elements," IEEE Transactions on Information Theory, Vol. 1T-36, No. 6, pp. 1280-1284, November 1990.
- S. Unnikrishna Pillai and Brig Elliott, "Image Reconstruction from one bit of Phase Information," Journal of Visual Communication and Image Representation, Vol. 1, No. 2, pp. 153-157, November 1990.
- S. Unnikrishna Pillai, Theodore I. Shim and Hamid Benteftifa, "A New Spectrum Extension Method that Maximizes the Multi-Step Prediction Error-Generalization of the Maximum Entropy Concept," IEEE Transactions on Signal Processing, Vol. 40, No. 1, pp. 142-158, January 1992.
- D. C. Youla, S. Unnikrishna Pillai, and F. Winter, "Theory and Design of Maximally Flat Low-Pass, High-Pass Reactance-Ladder Diplexers", IEEE Transactions on Circuits and Systems-I, Vol. 39, No. 5, CAS-I, pp. 337-350, May 1992.
- S. Unnikrishna Pillai, T. I. Shim and D. C. Youla, "A New Technique for ARMA-System Identification and Rational Approximation," IEEE Transactions on Signal Processing, Vol. 41, No. 3, pp. 1281-1304, March 1993.
- T. I. Shim, S. Unnikrishna Pillai and W. C. Lee, "Uniqueness of a Two-Step Predictor Based Spectral Estimator That Generalizes the Maximum Entropy Concept," IEEE Transactions on Signal Processing, Vol. 41, No. 9, pp. 2942-2946, September 1993.
- L. Carin, L. B. Felsen, S. U. Pillai, D. Kralj, and W. C. Lee, "Dispersive Modes in the Time-Domain: Analysis and Time-Frequency Representation," IEEE Microwave and Guided Wave Letters, Vol. 4, No. 1, pp. 23-25, January 1994.
- ** S. Unnikrishna Pillai, Theodore I. Shim and Won Cheol Lee, "New Signal Processing Methods for the Identification of Minimum-Phase Systems and Rational Approximation of Nonrational Systems", Digital Signal Processing theme Volumes in Control and Dynamic Systems Series, Vol. 65, pp. 253-322, Ed. by C. Leondes, Academic Press, March 1994.
- W. C. Lee and S. Unnikrishna Pillai, "Multichannel Stable Systems that Extend the Partial Impulse Response Matrices," IEEE Transactions on Signal Processing, Vol. 44, No. 10, pp. 2521-2536, October 1996.
- L. Carin, L. B. Felsen, D. Kralj, H.S. Oh, W. C. Lee and S. U. Pillai, "Wave- Oriented Signal Processing of Dispersive Time-Domain Scattering Data," IEEE Trans. on Antennas and Propagation, Vol. 45, No. 4, pp. 592-600, April, 1997.
- S. Unnikrishna Pillai and W. C. Lee, "Parametrization of Stable Systems from Partial Impulse Response Sequences," IEEE Transactions on Circuits and Systems-I: Fundamental Theory and Applications, Vol. 44, No.3, pp. 234-242, March 1997.
- D. C. Youla, F. Winter and S. Unnikrishna Pillai, "A New Study of the Problem of Compatible Impedences," International Journal of Circuits and Systems, Vol. 25, pp. 541-560, July 1997.
- S. Unnikrishna Pillai and Ben Liang, "Blind Image Deconvolution using a Robust GCD Approach," IEEE Transactions on Image Processing, Vol. 8, No. 2, pp. 295-301, February 1999.
- S. Unnikrishna Pillai, H.S. Oh, J. R. Guerci and D. C. Youla, "Matched Transmit-Receiver Design in Presence of Signal Dependent Interference," IEEE Trans. on Information Theory, Vol. 1T-46, No. 3, pp. 577-584, March 2000.
- S. Unnikrishna Pillai, Y. L. Kim and J. R. Guerci, "Generalized Forward/Backward Subaperture Smoothing Techniques for Sample Starved STAP," IEEE Transactions on Signal Processing, Vol. 48, No. 12, pp. 3569-3574, December 2000.
- D. A Garren et. al. (S. U. Pillai), " Full-Polarization Matched-Illumination for Target Detection and Identification," IEEE Trans. on Aerospace and Electronic Systems, Vol. 38, No. 3, pp. 824-837, July 2002.
- S. Unnikrishna Pillai, Torsten Suel, and Seunghun Cha, "The Perron-Frobenius Theorem and Some of its Applications," IEEE Signal Processing Magazine, March 2005.
- S. U. Pillai et. al. “Effect of Earth’s Rotation and Range Foldover on Space-Based Radar Performance”, Proc. IEEE Transactions on Aerospace and Electronic Systems, Vol. 42, No. 3, July 2006
- S. U. Pillai et. al. “Cramer-Rao Bounds for Target Parameters in Space Based Radar Applications”, To appear in Proc.IEEE Transactions on Aerospace and Electronic Systems, Vol. 44, No. 4, October 2008.