Practical Derivation of Slot Equivalent Admittance in Periodic Waveguides

This communication describes a procedure for obtaining the equivalent-admittance representation of a slot in a waveguide. The approach is general, but it is particularly interesting for periodic waveguides, because it does not require knowing the Green´s function of the wave guides or properly defining the ports in such waveguides. The procedure is demonstrated on a well-known rectangular waveguide. It is later applied to a periodic waveguide and used to design a small array. Measurements of the array performance are shown so as to validate the approach.