Analytic results, valid at resonance, for the admittance properties of an edge shunt slot on the narrow wall of rectangular waveguide have been derived by the use of electromagnetic field equations. Furthermore, additional formulas for the reflection, transmission coefficient and voltage amplitude generated by given incident wave are described. Finally, the measured results are compared with the theoretical values. It was found that the measured results were consistent with the theoretical results. Also the errors between computed and measured data are described.