Antenna Patterns - Electrical and Computer Engineering

Antenna Loss ResistanceThe antenna loss resistance (conductor and dielectric losses) for manyantennas is typically difficult to calculate. In these cases, the lossresistance is normally measured experimentally. However, the lossresistance of wire antennas can be calculated easily and accurately.Assuming a conductor of length l and cross-sectional area A which carriesa uniform current density, the DC resistance iswhere F is the conductivity of the conductor. At high frequencies, thecurrent tends to crowd toward the outer surface of the conductor (skineffect). The HF resistance can be defined in terms of the skin depth *.where : is the permeability of the material and f is the frequency in Hz.The skin depth for copper (F = 5.8×10 7 ®/m, : = : o = 4B×10 !7 H/m) maybe written as