High-Frequency Fields

Abstract

We consider a narrowband signal (see Chapter 4) in a lossless time-invariant isotropic medium of parameters ε₀ε and μ₀μ, whose relative permittivity ε and permeability μ may be space-dependent. We define the free-space propagation constant ${k_0} = \sqrt {{\varepsilon _0}{\mu _0}}$, the free-space intrinsic impedance ${\zeta _0} = \sqrt {{{{\mu _0}} \mathord{\left/ {\vphantom {{{\mu _0}} {{\varepsilon _0}}}} \right. \kern-\nulldelimiterspace} {{\varepsilon _0}}}}$, and the relative refractive index $n = \sqrt {\varepsilon \mu }$, space-dependent in general.