Our plan in this chapter is to approximate the charge distribution over a small region of an electrode as a constant and then to combine many of these approximations in a manner that results in a useful approximation to the exact solution of Poisson’s equation over all of space. The method of moments (MoM) technique breaks conductor surfaces into small planar regions, assumes a constant charge distribution on each region, approximates Poisson’s equation by a set of algebraic equations, and then creates an approximate solution by (exactly) solving these equations.

The term *method of moments* is derived from the use of *moment*, as in *momentum*, as a weighting function for multiplying a set of variables by before adding (or integrating) them. Sadiku traces the term back to a Russian literature origin.^{1} It was popularized in the United States by Harrington, who used the name in the title of his seminal text on the subject.^{2} The method of moments is a much more general technique than its application here portrays; the interested reader is encouraged to follow up with either of the above mentioned references.

Consider an unbounded space with a finite total area of ideal conductors present. Practically, of course, *unbounded* means everywhere, but the conductors that we are not considering are so far away as to be irrelevant to our discussion. The conductors can be either ideally thin (two-dimensional) ...

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