Higher Order Asymptotic Approximations of Eigenmodes for a Circular Waveguide Terminated by a Perfectly Matched Layer

In this paper, the improved asymptotic solutions of eigenmodes (leaky and Berenger modes) are provided for a circular waveguide terminated by a perfectly matched layer. Furthermore, a systematic asymptotic approach is developed by the inverse power series. Numerical simulations demonstrate that the high-precision asymptotic eigenmodes can be obtained.