Fast calculation of radiation patterns of antennas with cylindrical structure by applying asymptotic waveform evaluation in a spectrum of two-dimensional solutions

When calculating the radiation from 3D excitation elements in the vicinity of 2D cylindrical structures, or scattering from 2D cylindrical structures with oblique plane wave incident, it is very efficient to use a spectrum of 2D solutions (S2DS) (P.-S. Kildal et al., IEEE Trans. Antennas and Propagat., vol. AP-44, pp. 1183-1192, 1996). A large number of antennas can be modeled as 2D cylindrical structures with 3D excitation elements. This paper presents a fast algorithm for calculating the elevation radiation pattern by using asymptotic waveform evaluation (AWE) in S2DS, which has been implemented in G2DMULT. G2DMULT is a general algorithm based on the S2DS technique that calculates the spectral Green´s functions of 2D multiregion structures by using the method of moment (MoM) (P.-S Kildal, Proc. 1999 IEEE Antennas Propagat. Soc. Symp, pp. 2200-2203, 1999). By using this fast algorithm, only a few 2D solutions are needed in order to obtain the complete elevation pattern from /spl theta/=0/spl deg/ to 180/spl deg/. For the examples presented in the paper, three 2D solutions are sufficient in order to obtain an accurate representation of the elevation pattern. This represents nearly an order of magnitude faster computation than using the direct method.