The electric field very near a driven cylindrical antenna

摘要

A first-order formula is derived for the component Ez(ρ, z) of the electric field very near to the surface and parallel to the axis of a perfectly conducting center-driven cylindrical antenna with radius α and length 2h. It has the form Ez(ρ, z)=Ez(z) ln(ρ/α) where ρ is the radial distance from the axis of the antenna and Ez(z) is a complicated expression that involves generalized sine and cosine integral functions. Zero-order results are compared with first-order values for half- and full-wave dipoles with α/λ = 7.022 × 10. It is shown that zero-order values do not include large values of Ez(ρ, z) near the ends and near the driving point, so that a quantitative estimate of the field near a center-driven cylindrical antenna requires a first-order evaluation.