Читать книгу Introduction To Modern Planar Transmission Lines - Anand K. Verma - Страница 148

The magnetic materials support magnetization, i.e. magnetic polarization by the magnetic field. It also supports magnetic displacement current due to the time‐dependent magnetic field:

(4.1.11)

A diamagnetic material has permeability μ ≤ μ₀ and a paramagnetic material has permeability μ > μ₀. The diamagnetic behavior is caused by induced magnetic dipole moments, creating a magnetic field that opposes the externally applied magnetic field. However, the paramagnetic property comes into existence due to the alignment of already randomly existing magnetic dipole moments in the material. The conducting ferromagnetic materials have much larger permeability due to domain formation. However, the engineered artificial magnetic materials can have relative permeability less than unity, 0 < μ_r < 1. These are known as the mu near‐zero (MNZ) materials [B.16]. Again, the engineered materials can also have mu negative, giving the mu negative (MNG) materials. It is discussed in section (5.5) of chapter 5.