Physics-based aggregate-functions approaches to large MoM problems

Aggregate functions approaches construct efficient MoM basis functions by suitably grouping standard (e.g. Rao-Wilton- Glisson) functions. The application domains, objectives and related means of achieving them can be significantly different. In this paper we review some recent advances in aggregatefunctions methods, putting them in a unifying perspective. We address matrix compression, multi-resolution sets, low- and high-frequency constructs. They can reduce the degrees of freedom of the problem so as to allow a direct, iteration-free solution, or can accelerate the convergence rate of iterative methods. We analyze compressive methods in more detail, providing general discussion and specific implementation examples.