A novel aspect independent resonance based radar target discrimination method has been developed in a previous work, and is found to be effective in discriminating canonical shape closely resembling objects with minor structural variations. The method utilizes the Radar Cross Section (RCS) of the unknown target to be identified and the distinction polynomial stored in the database (built from the dominant resonances of the known target). In this paper, the method is implemented successfully to discriminate two real size F5 aircraft with minor structural variations between them. This study involving real size targets poses some challenges that are overcome in this paper. The foremost challenge is the accurate computation of resonance range RCS of electrically large sized target considered (> 10λ), which is computationally demanding. The second challenge is in selecting the dominant resonances (features) of the complex target, useful for discrimination, from a large set of resonances representing the target. The accuracy of the discrimination result is dictated by the accuracy with which the features of the targets are identified. This in turn is dependent on the accuracy with which RCS is determined. To achieve accurate results, the exact Computational Electromagnetic (CEM) method - the Method of Moments (MoM) is used for computing the RCS of real size aircraft. The procedure to choose an optimal number of dominant natural resonant frequencies (NRFs) from a pool of NRFs for real size complex target is presented in this paper. The discrimination quantifying function `Risk' is shown to be effective in discriminating F5 aircraft - with and without missile attached underneath. The two targets have been successfully discriminated at all aspects, which is yet another challenge, establishing the aspect independent discrimination capability of the technique.
2. Anuradha, S. and J. Balakrishnan, "Resonance based discrimination of targets with minor structural variations," 2016 Asia-Pacific Microwave Conference (APMC), 1-5, New Delhi, doi: 10.1109/APMC.2016.7931379, 2016.
3. Baum, C. E., "On the singularity expansion method for the solution of electromagnetic interaction problems,", Interaction Notes, 1971.
4. Lui, H. S. and N. V. Shuley, "Radar target identification using a “Banded” E-pulse technique," IEEE Transactions on Antennas and Propagation, Vol. 54, No. 12, 3874-3881, Dec. 2006.
5. Lee, J. H. and H. T. Kim, "Radar target discrimination using transient response reconstruction," Journal of Electromagnetic Waves and Applications, Vol. 19, No. 5, 655-669, Apr. 2005.
6. Morales, J. D., D. Blanco, D. P. Ruiz, and M. C. Carrion, "Radar-target identification via exponential extinction-pulse synthesis," IEEE Transactions on Antennas and Propagation, Vol. 55, No. 7, Jul. 2007.
7. Morales, J. D., D. Blanco, D. P. Ruiz, and M. C. Carrion, "Non cooperative radar target identification using exponential single-mode extraction pulse," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 6, 2064-2072, Jun. 2011.
8. Chen, W. C. and N. V. Shuley, "Resonance based radar target identification using principal component analysis," 2008 Asia-Pacific Microwave Conference, 2008.
9. Gallego, A., M. C. Carrion, D. P. Ruiz, and A. Medouri, "Extended E-pulse technique for discrimination of conducting spheres," IEEE Transactions on Antennas and Propagation, Vol. 41, No. 10, 1460-1462, Oct. 1993.
10. Toribio, R., J. Saillard, and P. Pouliguen, "Identification of radar targets in resonance zone: E-pulse techniques," Progress In Electromagnetics Research, Vol. 43, 39-58, 2003.
11. Baev, A., Y. Kuznetsov, and A. Aleksandrov, "Ultra wideband radar target discrimination using the signatures algorithm," 2003 33rd European Microwave Conference, 987-990, Munich, Germany, 2003.
12. Rothwell, E., D. Nyquist, K.-M. Chen, and B. Drachman, "Radar target discrimination using the extinction-pulse technique," IEEE Transactions on Antennas and Propagation, Vol. 33, No. 9, 929-937, Sep. 1985.
13. Rajalakshmi Menon, K., "Application of high frequency natural resonances extracted from electromagnetic scattering response for discrimination of radar targets with minor variations,", Thesis: IISc, 2001.
14. Sarkar, T. K. and O. Pereira, "Using the matrix pencil method to estimate the parameters of a sum of complex exponentials," IEEE Antennas and Propagation Magazine, Vol. 37, No. 1, 48-55, Feb. 1995, doi: 10.1109/74.370583.
15. Gustavsen, B. and A. Semlyen, "Rational approximation of frequency domain responses by vector fitting," IEEE Trans. Power Delivery, Vol. 14, No. 3, 1052-1061, Jul. 1999.
16. Lin, M.-C. and Y.-W. Kiang, "Target discrimination using multiple-frequency amplitude returns," IEEE Trans. Antennas and Propagation, Vol. 38, No. 11, 1885-1889, Nov. 1990.
17., "FEKO. Software of electromagnetic simulation,", [Online] Available: https://altairhyperworks-.com/product/FEKO.
18. Upendra Raju, A. and J. Balakrishnan, "Performance analysis of CEM techniques for prediction of RCS of a complex shaped body," International Journal of Applied Engineering Research (IJAER), Vol. 7, No. 4, 411-420, 2012.
19. Anuradha, S., G. U. Varalakshmi, and J. Balakrishnan, "Discrimination of complex radar targets using the dominant poles determined in the time and frequency domains," IETE Journal of Research, 2019, DOI: 10.1080/03772063.2019.1565953.