Fundamental mode
= Fundamental mode
{title2=$n=0$}
The <fundamental mode> is the lowest-frequency oscillatory mode for the specified geometry, constraints and, in a propagation problem, horizontal <wavenumber>. Its <frequency> need not be a universal constant of the material. In a <waveguide> it forms the lowest <dispersion> branch; rigid zero-frequency motions, when present, must be distinguished from oscillations.