The Electric Field Very Near a Driven Cylindrical Antenna

A first‐order formula is derived for the component E z ( 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 a and length 2h. It has the form E z ( ρ, z ) = E z (z) ln ( ρ/a ) where p is the radial distance from the axis of the antenna and E z ( 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 a / λ = 7.022 × 10 ∑3 . It is shown that zero‐order values do not include large values of E z ( 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.