A Near-Field Virtual Equivalent Source-Based Iterative Fast Fourier Transform Technique for Pattern Synthesis of Conformal Arrays

This letter presents a far-field pattern synthesis solution for arbitrary conformal arrays employing a near-field virtual equivalent source-based iterative fast Fourier transform (NFVES-IFFT) technique. Far-field calculation of a conformal array is transformed into the pattern-multiplication form by the equivalent sources, and the input-to-pattern forward evaluation is realized and accelerated via the equivalent source expansion and 2-D inverse FFT operation. Contrarily, the pattern-to-input backward calculation is also presented by analyzing the contribution of each type of equivalent source on the far fields at all observation angles and the 3-D FFT technique. An NFVES-IFFT process based on the above forward and backward calculations is further proposed and used to realize pattern synthesis. Representative examples are provided to validate the advantages of the proposed technique.