The omnidirectional leaky coaxial waveguides are analysed by the finite-difference timedomain (FDTD) method in cylindrical coordinates. All structural details and electromagnetic characteristics can be accurately modelled in this FDTD analysi Also, the effects of all electromagnetic phenomena are
accurately taken into account. A selection of obtained numerical results is presented containing the radiation characteristics of a single circumferential slot on coaxial waveguide, the effects of coupling between two circumferential slots and the radiation characteristics and patterns of coaxial waveguides with 40 periodic slots. Some of these results are compared with those obtained by other methods to confirm the accuracy of simulations.