2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.

IEEE Transactions on Antennas and Propagation
Volume 48 Number 7, July 2000

Optimizing a Large Array Configuration to Minimize the Sidelobes

Page 1075.

Abstract:

A new method of minimizing sidelobes of a large array whose element spacing is much larger than the wavelength has been developed. The analytical expression for the first derivative of the array beam in respect to the element shift of the array is obtained. Using this expression, it is possible to minimize the value of a beam pattern for a given direction. The minimization of the array's worst sidelobe is carried out iteratively. At each iteration, the worst sidelobe found is suppressed. A task in the National Radio Astronomy Observatory (NRAO) astronomical image processing system (AIPS) was written to apply the optimization algorithm. This task provides the optimization of the array's element position and plots the initial and optimized configurations. The optimization can be carried out under the following constraints: doughnut, two circumferences,topography, and minimum spacing between the array elements. Another constraint can be added. The area of the sidelobes' minimizing is the circle in the sky with the center at the main beam.

References

1. C. L. Dolph, "A current distribution for broadside arrays which optimizes the relationship between beam width and sidelobe level", Proc. IRE, vol. 34, pp.  335-348, June  1946.
2. C. A. Olen and R. T. Compton, "A numerical pattern synthesis algorithm for arrays", IEEE Trans. Antennas Propagat., vol. 38, pp.  1666-1676, Oct.  1990.
3. C.-Y. Tseng and L. J. Gripffiths, "A simple algorithm to achieve desired patterns for arbitrary arrays", IEEE Trans. Signal Processing, vol. 40, pp.  2737-2746, Nov.  1992.
4. A. Ishimaru, "Theory of unequally spaced arrays", IEEE Trans. Antennas Propagat., vol. AP-11, pp.  691-702, Nov.  1962 .
5. B. P. Kumar and G. R. Branner, "Design of unequally spaced arrays for performance improvement", IEEE Trans. Antennas Propagat., vol. 47, pp.  511-524, Mar.  1999.
6. S. Kirkpatrick, C. D. Gelatt Jr. and M. P. Vecchi, "Optimization of simulated annealing", Sci., vol. 220, pp.  671-679, 1983.
7. T. J. Cornwell, "A novel principle for optimization of the instantaneous fourier plane coverage of correlation arrays", IEEE Trans. Antennas Propagat., vol. 36, pp.  1165-1167, Aug.  1988.
8. P. J. Napier, A. R. Thompson and R. D. Ekers, "The very large array: Design and performance of a modern synthesis radio telescope", Proc. IEEE, vol. 71, pp.  1295-1320,  1983.
9. P. J. Napier, D. S. Bagri, B. G. Clark, A. E. E. Rogers, J. D. Romney, A. R. Thomson and R. C. Walker, "The very long baseline array", Proc. IEEE, vol. 82, no. 5, pp.  658-672, 1994.