Revisiting Levin+Li acceleration method for rapid diffraction analysis of reflector antennas

The Levin method, improved by Li, is shown to accelerate, by about three orders of magnitude, the brute-force physical optics radiation from a parabolic reflector of 240 wavelengths, especially in the far-out sidelobe regions. Key steps involve the use of an accelerating approximation involving a delaminating quadrature suggested by Li, sampling at Chebyshev-Lobatto nodes, the Chebyshev differential matrix, and truncated singular value decomposition. This paper revisits the application of the Levin+Li method and tailors it specifically to accelerate calculations for parabolic reflector antennas.