In this paper, the cosinusoidal slot aperture distribution is replaced with a two term approximation. Using this two term approximation, the slot fields are evaluated in closed form and explicit expressions are given in terms of sine and cosine integrals. The two term approximation and the near fields derived therefrom agree closely with the cosinusoidal distribution for slot lengths upto 0.65λ, with an error of less than 3.3% with respect to the numerical results upto 0.05λ from the slot in the near field. The formulation given here is of practical use in estimating mutual coupling in an array or in estimating radiated emissions for Electromagnetic Compatibility (EMC) analysis.
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