In this paper, we propose an optimization method based on Gravitational Search Algorithm (GSA) for design of reconfigurable dual-beam concentric ring array of isotropic elements with phase only control of five-bit digital phase shifters. The problem is to find a common radial amplitude distribution using four-bit digital attenuator that will generate three different types of broadsided beam pair in vertical plane: a pencil/pencil beam pair, a pencil/flat-top beam pair and a flat-top/flat-top beam pair sector pattern) with desired value of side lobe level, first null beam width and ripple. The two patterns differ only in radial discrete phase distribution while sharing a common discrete radial amplitude distribution. The optimum sets of four-bit discrete radial amplitude distribution generated by four-bit digital attenuators and five-bit discrete radial phase distribution generated by five-bit digital phase shifters for obtaining dual radiation patterns are computed by Gravitational Search Algorithm.
2. Durr, M., A. Trastoy, and F. Ares, "Multiple-pattern linear antenna arrays with single prefixed amplitude distributions: Modified Woodward-Lawson synthesis," Electronics Letters, Vol. 36, No. 16, 1345-1346, Aug. 2000.
3. Bucci, O. M., G. Mazzarella, and G. Panariello, "Reconfigurable arrays by phase-only control," IEEE Trans. Antennas and Propag., Vol. 39, No. 7, 919-925, Jul. 1991.
4. Gies, D. and Y. Rahmat-samii, "Particle swarm optimization for reconfigurable phase-differentiated array design," Microwave Opt. Technol. Lett., Vol. 38, 168-175, Aug. 2003.
5. Mahanti, G. K., A. Chakraborty, and S. Das, "Design of fully digital controlled reconfigurable array antennas with fixed dynamic range ratio," Journal of Electromagnetic Waves and Applications, Vol. 21, No. 1, 97-106, 2007.
6. Mahanti, G. K., A. Chakraborty, and S. Das, "Design of phase-differentiated reconfigurable array antennas with minimum dynamic range ratio," IEEE Antennas and Wireless Propagation Letters, Vol. 5, 262-264, Dec. 2006.
7. Stearns, C. and A. Stewart, "An investigation of concentric ring antennas with low sidelobes," IEEE Trans. Antennas Propag., Vol. 13, No. 6, 856-863, Nov. 1965.
8. Goto, N. and D. K. Cheng, "On the synthesis of concentric-ring arrays," IEEE Proc., Vol. 58, No. 5, 839-840, May 1970.
9. Biller, L. and G. Friedman, "Optimization of radiation patterns for an array of concentric ring sources," IEEE Trans. Audio Electroacoust., Vol. 21, No. 1, 57-61, Feb. 1973.
10. Huebner, D., "Design and optimization of small concentric ring arrays," Proc. IEEE Antennas Propagation Int. Symp., Vol. 16, 455-458, May 1978.
11. Kumar, B. P. and G. R. Branner, "Design of low side lobe circular ring array by element radius optimazation," Proc. IEEE Antennas Propagation Int. Symp., 2032-2035, Orlando, FL, Aug. 1999.
12. Dessouky, M. I., H. A. Sharshar, and Y. A. Albagory, "Efficient sidelobe reduction technique for small-sized concentric circular arrays," Progress In Electromagnetics Research, Vol. 65, 187-200, 2006.
13. Haupt, R. L., "Optimized element spacing for low side lobe concentric ring arrays," IEEE Trans. Antennas Propag., Vol. 56, No. 1, 266-268, Jan. 2008.
14. Pathak, N., G. K. Mahanti, S. K. Singh, J. K. Mishra, and A. Chakraborty, "Synthesis of thinned planar circular array antennas using modified particle swarm optimization," Progress In Electromagnetics Research Letters, Vol. 12, 87-97, 2009.
15. Chatterjee, A., G. K. Mahanti, and N. Pathak, "Comparative performance of gravitational search algorithm and modified particle swarm optimization algorithm for synthesis of thinned scanned concentric ring array antenna," Progress In Electromagnetics Research B, Vol. 25, 331-348, 2010.
16. Dessouky, M. I., H. A. Sharshar, and Y. A. Albagory, "Optimum normalized-Gaussian tapering window for side lobe reduction in uniform concentric circular arrays," Progress In Electromagnetics Research, Vol. 69, 35-46, 2007.
17. Dessouky, M., H. Sharshar, and Y. Albagory, "A novel tapered beamforming window for uniform concentric circular arrays," Journal of Electromagnetic Waves and Applications, Vol. 20, 2077-2089, 2006.
18. Chen, T. B., Y. L. Dong, Y. C. Jiao, and F. S. Zhang, "Synthesis of circular antenna array using crossed particle swarm optimization algorithm," Journal of Electromagnetic Waves and Applications, Vol. 20, No. 13, 1785-1795, 2006.
19. Rashedi, E., H. Nezamabadi-Pour, and S. Saryazdi, GSA: A Gravitational Search Algorithm, Vol. 179, No. 13, 2232-2248, Information Sciences, 2009.