WIENER-HOPF ANALYSIS OF THE DIFFRACTION BY A PARALLEL-PLATE WAVE-GUIDE CAVITY WITH PARTIAL MATERIAL LOADING

The plane wave diffraction by a two-dimensional parallel-plate wavegui de cavity with partial material loading is rigorously analyzed for bot h the E and the H polarization using the Wiener-Hopf technique. Introd ucing the Fourier transform for the scattered field and applying bound ary conditions in the transform domain, the problem is formulated in t erms of the simultaneous Wiener-Hopf equations satisfied by the unknow n spectral functions. The Wiener-Hopf equations are solved exactly via the factorization and decomposition procedure leading to the formal s olution, which involves branch-cut integrals with unknown integrands a s well as infinite series with unknown coefficients. Applying rigorous asymptotics with the aid of the edge condition, the approximate solut ion to the Wiener-Hopf equations is derived in the form suitable for n umerical computations. The scattered field inside and outside the cavi ty is evaluated by taking the inverse Fourier transform together with the use of the saddle point method. Numerical examples of the radar cr oss section are presented for various physical parameters, and the far field backscattering characteristics of the cavity are discussed in d etail. Some comparisons with a high-frequency technique are also given to validate the present method.