TMpolarisering

TMpolarisering, or transverse-magnetic polarization, describes a state of electromagnetic wave polarization in which the magnetic field is entirely transverse to the direction of propagation (no longitudinal magnetic field component), while the electric field generally has a component along the propagation direction. For a wave moving in the z direction, this is characterized by Hz = 0 and Ez ≠ 0 (with Hx and Hy present). This contrasts with TE polarization, where Ez = 0 and the magnetic field can contain a longitudinal component. The term is primarily used in the analysis of guided waves and structured media, such as waveguides and planar dielectric or metamaterial layers.

In waveguides, TM modes arise as solutions to Maxwell's equations under boundary conditions imposed by the walls or interfaces. TM modes feature a nonzero Ez field and have specific cutoff frequencies that depend on the cross-sectional geometry (for rectangular or circular guides). TE and TM modes constitute separate families of guided waves, while TEM modes (where both Ez and Hz are zero) occur in structures like coaxial cables.

Applications of TMpolarisering include microwave transmission via waveguides, polarization-controlled signaling, and planar photonics where polarization dependence matters. TM polarization is used for mode matching and selective excitation of guided waves, and it intersects with the design of metamaterials and RF components. In optical fibers and cylindrical structures, achieving and maintaining a pure TM state can be challenging due to symmetry and mode coupling.