The prolate spheroidal antenna: Current and impedance

This paper studies the near field of the prolate spheroidal antenna. By expanding the components of the electromagnetic field in terms of the spheroidal functions, we determine the current distribution over the antenna and the impedance at the gap. We consider both center and off-center gaps for
kL = 1, 1.49, 2, 3, 4
, where
k =2\pi/\lambda, L
is the semifocal length of the spheroid, and
\lambda
is the wavelength. The radiation resistance is calculated from the far field and found to be in excellent agreement with the resistance at the gap calculated from the near field.