Current distribution along a probe in waveguide

There are three different formulae for the current distribution along a probe in a rectangular waveguide. The question of which one can more accurately describe the current distribution is answered using the moment method. The numerical solution for the current along the probe is obtained by solving the surface integral equation, which is set up utilizing the boundary condition. The pulse basis and point-matching moment procedure are applied. A new approximate expression for the current is given using the curve-fitting technique. The results show that the new expression is more accurate than any other available expressions, and it provides a good basis for solving other problems of posts in waveguides.<>