Abstract: In this paper, the basic property of the electro-magnetic wave propagation on a periodic notched planar structure is analysed and is pointed out that it is often necessary to simplify this kind of problems into boundary value problems in the boundary impedance condition. The key to the problem is to determine the surface impedance, when the period of the structure is not too long and the notch wall sufficiently thin, we can define equivalent surface reactance by reference to the reflection of the plane wave, and the problem of periodic notched structure can be approximately solved according to the condition of the uniform surface reactance.
The approach of normal component of the electrical field on the periodic notched structure being expanded into the Fourier integral has been used and the functional equations are set up according to the boundary condition. Using the Wiener-Hopf method, expressions of the secondary field and reflection coefficients are obtained, and Finally the expression of the surface reactance is found. The measured results are in good agreement with those found by theoretical methods. Thus, it is of practical value to simplify analytic and calculating methods of electromagnetic propagation and scattering on the periodic notched planar structure.