arXiv:2610.19982v1 Announce Type: new Abstract: We study a spherical perfectly matched layer (PML) method for the time-harmonic Maxwell scattering problem with large wavenumber. Using vector spherical harmonics and a modal transformation for the coupled transverse magnetic components, we establish the sharp wavenumber-explicit stability estimate for the truncated PML problem and prove that its inf-sup constant is of order $O(\kappa^{-1})$. We then analyze the first-order N\'ed\'elec edge element method and its continuous interior penalty counterpart. Under the condition that $\kappa^3h^2$ is sufficiently small, the preasymptotic errors in the energy norm and the $\kappa$-scaled $\mathbf{L}^2$ norm are of orders $O(\kappa h+\kappa^3h^2)$ and $O(\kappa^2h^2+\kappa^3h^2)$, respectively. Numerical experiments confirm the theoretical results.