Method of Modal Basis: A Tribute to Oleg A. Tretyakov

This paper commemorates the late Professor Oleg Alexandrovich Tretyakov, a highly respected expert in the fields of electrodynamics and radiophysics. Professor Tretyakov served as the Commission B Chair of the Ukrainian URSI Committee from 1993 until his passing on January 25th, 2022. His analytical approach was acknowledged as an alternative to the time-harmonic field method and was successfully applied to cavity and waveguides problems for several decades. Highlighting the novelty of his method, the paper reviews Professor Tretyakov’s main contributions to electrodynamics. He will be greatly missed by his friends, colleagues, and the scientific community.