Spatial sideband
= Spatial sideband
= Sideband
{synonym}
A spatial sideband is a Fourier perturbation with <wavenumber> close to a pattern's carrier <wavenumber>, such as $k_c+p$ or $k_c-p$. A real physical field also includes the conjugate Fourier component. Linearizing a nonlinear complex <amplitude equation> can couple the two displaced components, so testing only a single uniform amplitude misses their joint <linear stability> problem.