On the admittance of a monopole driven from a coaxial line

A simple formula is described for the apparent admittance Y(ka, b/a) of a monopole of fixed length h and radius a when driven from a coaxial line (conductor radii b and a ). If Y(ka, b/a) is known at n values of ka with b/a fixed at (b/a)_{2} and at m values of b/a with ka fixed at (ka)_{1} , it can be evaluated from the given formula for all combinations of ka and b/a in the two ranges of n and m . It is assumed that kb \ll 1 and h \gg (b-a) .