For a long time power pattern synthesis has been considered to produce shaped beam patterns due to the number of degrees of freedom when compared with field pattern synthesis. However, severaladv antages exist if synthesis techniques are based on field patterns, since the relationship between the array factor and the source distribution is a Fourier transform. In this case, quicker and efficient algorithms are obtained with the Fast Fourier Transform (FFT) to perform the calculations. Therefore, this work presents a new technique that synthesizes shaped beam patterns through the control of non-uniformly samples of the array factor, both in amplitude and phase. The sample phases increase the number of degrees of freedom. To produce complex patterns, the sample phases of the shaped beam region are used to create more oscillations in the ripple structure than the ones produced with the realpatterns. Not only this procedure yields a narrower transition region between the beam zone and the sidelobe zone but also smaller dynamic range ratios are obtained. Furthermore, it is described how to impose nulls in prescribed directions of the complex patterns. Some examples are presented to demonstrate the application of the synthesis technique.
2. Woodward, P. M. and J. D. Lawson, "The theoretical precision with which an arbitrary radiation-pattern may be obtained from a source of finite size," Journal IEE, Vol. 95, No. 37, 363-370, 1948.
3. Mailloux, R. J., Phased Array Antenna Handbook, Artech House, 1994.
4. Elliot, R. S. and G. J. Sten, "A new technique for shaped beam synthesis of equispaced arrays," IEEE Transactions on Antennas & Propagation, Vol. 32, No. 10, 1129-1133, 1984.
5. Orchard, H. J., R. S. Elliot, and G. J. Sten, "Optimising the synthesis of shaped beam antenna patterns," IEE Proceedings, Vol. 132, Pt. H, No. 1, 63-68, 1985.
6. Milne, K., "Synthesis of power radiation patterns for linear array antennas," IEE Proceedings, Vol. 134, Pt. H, No. 3, 285-296, 1987.
7. Hu, J.-L., C. H. Chan, K.-M. Luk, and S.-M. Lin, "Shaped-beam pattern synthesis for base station antenna in mobile communication system," Microwave and Optical Technology Letters, Vol. 24, No. 4, 226-228, 2000.
8. Shavit, R. and S. Levy, "A new approach to the Orchard-Elliot pattern synthesis algorithm using LMS and pseudoinverse techniques," Microwave and Optical Technology Letters, Vol. 30, No. 1, 12-15, 2001.
9. Casimiro, A. M. and J. A. Azevedo, "New techniques that unify the procedure of the analysis and synthesis of antenna arrays," Journal of Electromagnetics Waves and Applications, Vol. 19, No. 14, 1881-1896, 2005.
10. Azevedo, J. A. and A. M. Casimiro, "Non-uniform sampling and polynomial interpolation for array synthesis," IET Microw. Antennas Propagat., Vol. 1, No. 4, 867-873, 2007.
11. Azevedo, J. A., The use of non-uniform sample phases for array synthesis, 15th International Conference on Digital Signal Processing, 95-98, Cardiff, Wales, UK, 2007.
12. Cid, J. M., J. A. Rodrigues, and F. Ares, "Shaped power patterns produced by equispaced linear arrays: Optimized synthesis using orthogonalsin( Nx)/ sin(x) beams," Journal of Electromagnetics Waves and Applications, Vol. 13, 985-992, 1999.