Alternating Adaptive Projections in Antenna Synthesis

• Published in: IEEE transactions on antennas and propagation Vol. 58; no. 3; pp. 727 - 737
• Main Authors: Quijano, J.L.A., Vecchi, G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2010; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Adaptive arrays; Algorithms; Alternating projections; Annealing; Antenna arrays; antenna synthesis; Antennas; Applied sciences; Computation; Convergence; Convergence of numerical methods; Electromagnetic compatibility; Exact sciences and technology; Geometrical optics; intersection approach; Nonlinearity; Operators; Optimization methods; Projection; Projection algorithms; Radiocommunications; Robustness; Studies; Synthesis; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Testing; Performance evaluation; Scale invariance; Transmission protocol; Iterative method; Specification; optimization methods; Algorithm; Implementation; Optimization; intersection approach; Non linear operator; Projection method; Alternating projections; Projection operator; Adaptive antenna; Convergence rate; Routing protocols; Robustness; Antenna synthesis
• ISSN: 0018-926X; 1558-2221
• DOI: 10.1109/TAP.2009.2039307

The projection operator is a basic building block in the application of the alternating projections method to antenna synthesis. In general it is a non-linear operator that is repeatedly applied in the course of a single synthesis process, thus having a considerable impact on the convergence properties of the resulting algorithm. A novel approach to the computation of these projections is presented which exploits a simple definition of the relevant spaces (particularly that of radiated fields). Characterization of field mask specification as scale-invariant under this definition adds a further degree of freedom, namely reference level, which impacts on the (sensitive to scaling) projector. In order to compute the optimum reference level, an iterative procedure is proposed which is simple to implement, easily integrable in standard alternating projection routines, and adds negligible computational burden. Numerical tests confirm an improved performance with respect to the fixed-scaling projection operator in terms of convergence rate and robustness against the initial guess, supporting our approach as a valid aid in overcoming the drawbacks of the alternating projections-based antenna synthesis.