Читать книгу Introduction To Modern Planar Transmission Lines - Anand K. Verma - Страница 155

The plasma medium, i.e. the electron gas model of metal or ionosphere, is treated as an isotropic medium. However, in the presence of a static biasing magnetic field, it becomes a uniaxial dielectric material with off‐diagonal elements for the permittivity matrix. This permittivity matrix is anti‐symmetric. It does not support linearly polarized characteristic waves as the normal modes. It forms a gyroelectric medium, i.e. electrically gyrotropic medium. Similarly, in the presence of a static biased magnetic field in the z‐direction, ferrite medium becomes a gyromagnetic medium, i.e. magnetically gyrotropic medium. Both plasma and ferrite media, under the magnetic biasing, support propagation of circularly polarized characteristic waves as the normal modes [B.2–B.4, B.21, B.22]. The permittivity and permeability tensors in matrix form for these media are summarized below.