Estimation of reflection coefficients for an open-ended coaxial waveguide radiating into a chiral half-space

A spectral-domain moment method solution is presented for estimation of the reflection coefficients of an open-ended coaxial waveguide radiating into a chiral half-space, The electromagnetic fields in the waveguide region are expanded in the normal waveguide modes, while those in the half-space are formulated in terms of plane wave spectrum using two dimensional Fourier tr ansform. A spectral domain admittance matrix is derived through which an el ectric field integral equation can be obtained by matching the tangential f ield components on the open end interface. This integral equation is solved with the Galerkin method. The coefficients of the matrix equation are redu ced to one-dimensional integrals to facilitate numerical calculation. The p roblem is different from the case of isotropic non-chiral medium in that ch irality causes excitation of TE modes, whose effect is accounted for rigoro usly in the formulation. This is in contrast to plane wave reflected from a chiral media at normal incidence, where no depolarization effect can be ob served. Numerical results are presented to illustrate the idea that the ref lectivity of TEM mode carries information on the presence of chirality. The analysis has a potential application in developing an open-ended waveguide method for the characterization of chiral materials using only reflection measurements including depolarization effects.