Question

Briefly discuss the effects that the human body has on the propagation characteristics of BANs.

Answer 1

Human body can be considered as a multilayered structure with different tissues, such as skin, fat, and muscle. Each tissue has a frequency dependent dielectric property, characterized by a complex permittivity $\varepsilon _{c}=\varepsilon _{o}\varepsilon _{_{r}}=\varepsilon_{0} \left ( \varepsilon {_{r}^}^{'} \right-j\varepsilon {_{r}}^{''} )=\varepsilon_{0}\varepsilon {_{r}}^{'}-j\varepsilon_{0}\varepsilon {_{r}}^{''}$ , where ε0 is the vacuum permittivity and εr is the body tissue relative permittivity. Permittivity values for skin, fat, and muscle can be found in at frequencies ranging from 10 Hz up to 100 GHz. The thickness of tissue varies with different localization and different person: skin thickness may range from 0.1 to 5 mm, and fat from 1 to 30 mm. In most human part such as forearm and chest, skin thickness is about 1mm. In this paper, various skin thicknesses, typically 0.5 mm, 1 mm, and 1.5 mm, are considered and compared in calculations to show its influence on propagation.