antenna impedance calculation

HI, all. I got this equation from Balanis's <<Antenna Theory>>. Could any of you tell me how can I calculate the value of G12? Any help will be appreciated.
(ko, W, L are given) where Jo is the Bessel Function of the first kind of order zero

hello,

the only way to calculate G12 is by using numerical integration.
in octave or matlab try the quad function.
there appears to be a singular point at pi/2. try integrating from 0 to pi/2 (not included) and from pi/2 to pi, than add the 2 results.
or, octave has a built-in function for integrating an expression with singular values. I am not sure whether matlab has a similar function.

greets