In this paper, the optimization of both sum and difference patterns of linear monopulse antennas with low side lobe levels, high directivity and also narrow main beam width are efficiently solved by Continuous Ant Colony Optimization (ACO) Method. The synthesis problem is optimized by defining a suitable cost function which is based on limitation of the side lobe level. In this work, three different parameters are considered to be optimized separately which are the excitation amplitude of each element, the excitation phase of each element and finally the element-to-element spacing. Numerical results of each step, sum and difference patterns, are illustrated in each related part. Finally, we investigate placing some nulls in specific directions to suppress the jamming signals in both sum and difference patterns.
2. Rodriguez, J. A. and F. Ares, "Optimal compromise between sum and difference patterns while fixing quasi-nulls in both," Journal of Electromagnetic Waves and Applications, Vol. 13, 655-664, 1999.
3. Ares, F., S. R. Rengarajan, J. A. Rodriguez, and E. Moreno, Optimal compromise among sum and difference patterns through sub-arraying, IEEE Antennas and Propagation Society International Symposium, 1142-1146, 1996.
4. Caorsi, S. and A. Massa, "Optimization of the difference patterns for monopulse antennas by a hybrid real/integer-coded differential evolution method," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 1, 2005.
5. Mahanti, G. K., N. Pathak, and P. Mahanti, "Synthesis of thinned linear antenna arrays with fixed sidelobe level using realcoded genetic algorithm," Progress In Electromagnetics Research, Vol. 75, 319-328, 2007.
6. Lu, Y. Q. and J. Y. Li, "Optimization of broadband top-load antenna using micro-genetic algorithm," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 6, 793-801, 2006.
7. Yan, K. and Y. Lu, "Sidelobe reduction in array-pattern synthesis using genetic algorithm," IEEE Trans. Antennas Propag., Vol. 45, No. 7, 1117-1122, 1997.
8. Haupt, R. L., "Thinned arrays using genetic algorithms," IEEE Trans. Antennas Propag., Vol. 42, No. 7, 993-999, 1994.
9. Mohamed, M. A., E. A. Soliman, and M. A. El-Gamal, "Optimization and characterization of electromagnetically coupled patch antennas using RFB neural networks," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 8, 1101-1114, 2006.
10. Murino, V., A. Trucco, and C. Regazzoni, "Synthesis of unequally spaced arrays by simulated annealing," IEEE Trans. Signal Process., Vol. 44, No. 1, 119-123, 1996.
11. Chen, T. B., Y. L. Dong, Y.-C. Jiao, and F.-S. Zhang, "Synthesizes of circular antenna array using crossed particle swarm optimization algorithm," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 13, 1785-1795, 2006.
12. Khodier, M. M. and C. G. Christodolou, "Linear array geometry synthesis with minimum sidelobe level and null control using particle swarm optimization," IEEE Trans. Antennas Propag., Vol. 53, No. 8, 2674-2679, 2005.
13. Mallahzadeh, A. R., H. Oraizi, and Z. Davoodi-Rad, "Application of the invasive weed optimization technique for antenna configurations," Progress In Electromagnetics Research, Vol. 79, 137-150, 2008.
14. Quevedo-Teruel, O. and E. Rajo-Iglesias, "Ant colony optimization in thinned array synthesis with minimum sidelobe level," IEEE Antennas and Wireless Propagation Letters, Vol. 5, 349-352, 2006.
15. Coleman, C. M., E. J. Rothwell, and J. E, Ross, "Investigation of simulated annealing, ant-colony optimization, and genetic algorithms for self-structuring antennas," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 4, 2004.
16. Guney, K. and M. Onay, "Amplitude-only pattern nulling of linear antenna arrays with the use of bees algorithm," Progress In Electromagnetics Research, Vol. 70, 21-36, 2007.
17. Akdagli, A., K. Guney, and B. Babayigit, "Clonal selection algorithm for design of reconfigurable antenna array with discrete phase shifters," Journal of Electromagnetic Waves and Application, Vol. 21, No. 2, 215-227, 2007.
18. Dorigo, M. and T. Stutzle, Ant Colony Optimization, MIT Press, Cambridge, MA, 2004.
19. Dorigo, M., G. D. Caro, and L. Gambardella, "Ant algorithms for discrete optimization," Artif. Life, Vol. 5, No. 2, 137-172, 1999.
20. Socha, K., Extended ACO for continuous and mixed-variable opimization, Proceedings of ANTS 2004 — Fourth International Workshop on Ant Algorithms and Swarm Intelligence, 2004.
21. Balanis, C. A., Antenna Theory: Analysis and Design, Wiley, New York, 2005.
22. Ho, S. L. and S. Yang, "An improved ant colony optimization algorithm and its application to electromagnetic devices designs," IEEE Transactions on Magnetics, Vol. 41, No. 5, 2005.
23. Demir, S., "Matching circuit design using ant colony optimization method," 0-7803-7846-6/03, IEEE, 2003.