Constrained optimization of monopulse circular aperture distribution in the presence of blockage

Abstract

Absfracf-A method of synthesizing aperture antenna excitations to obtain optimum performance in the presence of aperture blockage is presented. The problem of optimizing the performance indices such as directivity and angular sensitivity is formulated as an N-dimensional minimization problem, with constraint on the sidelobe level. In most cases, the objective function is nonlinear with multiple minima which does not yield readily to gradient methods. A simplex search method is used in the study for optimizing the performance index. The sidelobe level (SLL) constraint has been incorporated using the penalty function method. The method is applied to circular monopulse aperture distribution with circular blockage to obtain maximum directivity factor (DF) in the sum mode and maximum angular sensitivity factor (ASF) in the difference mode, with sidelobe level constraint. The effect of blockage on the maximum directivity and maximum angular sensitivity is studied for various sidelobe level constraints.

Modal Field Synthesis of Monopulse Difference Patterns for Radiating Aperture

“…As stated in the introduction, given the key role antenna arrays play in the design of monopulse systems [3]- [8], it would be possible in future work to apply this formulation to the design of array difference patterns by establishing an analogy between the modal field functions of the radiating aperture and the fields radiated by the elements of the array. Furthermore, given the importance of sidelobe control in monopulse radar applications both for arrays [28] and apertures [29], future work could be carried out to introduce additional constraints regarding side lobe or cross-polarization levels to the formulation, though at the expense of a more complex optimization problem (i.e. requiring algorithms to be solved), with no direct closed-form solution as in this work.…”