Glossary
HF-Guiding structures: Modelling and calculations

Fashion; fashion

A discrete solution to the Helmholtz equation, in which the fields can propagate (propagating mode) or decay (evanescent mode) in a uniform waveguide.

Cutoff

A phenomenon that, at the so-called cutoff frequency, transforms a propagating mode—which carries active power—into an evanescent mode that stores pure reactive power.

Degenerate modes

Modes with the same dispersion curve but different field configurations. They do not have the same frequency-dependent attenuation curves.

Eigenvalue problem

A problem whose formulation yields a homogeneous system. A non-trivial solution (one that is not identically zero) can exist only if the determinant of the system matrix is zero, which generates a polynomial...