We present a new approach to the problem of radiation by a coaxial line into a half-space. We obtain boundary-integral equations for the current densities over the walls of the coax and its opening to the half-space. Using the modes of the coax for basis and testing functions, we convert the integral equations to an infinite system of linear equations, the unknowns being the coeffi- cients of the current density expansions. We demonstrate how, by solving a small subsystem, we can obtain the fields everywhere in space.
