TM SURFACE WAVE DIFFRACTION BY A TRUNCATED DIELECTRIC SLAB RECESSED IN A PERFECTLY CONDUCTING SURFACE

摘要

The diffraction of a TMo surface wave by a terminated dielectric slab which is flush mounted in a perfectly-conducting surface is studied. The incident surface wave gives rise to waves reflected and diffracted by the termination; these reflected and diffracted fields may be expressed in terms of the geometrical theory of diffraction by introducing surface wave reflection and diffraction coefficients which are associated with the termination. In this investigation, the surface wave reflection and diffraction coefficients have been deduced from a formally exact solution to this canonical problem. The solution is obtained by a combination of the generalized scattering matrix technique and function theoretic methods. Expressions for the reflection and diffraction coefficients contain integrals which can be evaluated numerically. Calculated values for the TMo surface wave reflection and diffraction coefficients and presented, and compared with approximate values obtained from a surface reactance model and from a varia¬tional solution of the canonical problems; the accuracy and shortcomings of these approximations are discussed. The relevance of the results obtained here to the design of a phased array of slots radiating through a flush mounted dielectric cover, and to the design of surface wave antennas is discussed. It is noted that spacecraft antennas may consist of such dielectric covered slot arrays.