Leakage from slotted waveguides is a well-known phenomenon and has been thoroughly investigated during the past decades. The interest in leaky-wave antennas mainly stems from the possibility of scanning the beam with frequency. The analysis of slotted waveguides has been first performed by means of a transverse network representation of the open structure since the milestone paper by Goldstone and Oliner. As a matter of fact, the method is simple but accurate, and can be easily extended to deal with structures more complicated than the standard slitted waveguide addressed in, such as groove guides and stub-loaded waveguides. Unfortunately it is not always possible to find a transverse equivalent network, in which case it is necessary rely on more general, but time-consuming, numerical methods