Asymptotic Approximation of Mutual Admittance Involved in MoM Analysis of RLSA Antennas

In this paper, a computationally efficient method of moments (MoM) formulation is presented that makes use of an approximate asymptotic formula for the slot mutual admittance. The formula accuracy to the asymptotic order O(r ^{- 3/2}) gives sufficient precision for moderate slot distance (1.5-2 wavelengths). In a typical radial line slot array analysis, this permits avoiding the numerical integration in more than 90% of the slot pairs with a savings of CPU time of the same order.