Design of Antireflection Grading Using Magneto-Dielectric Materials

A number of practical application areas would benefit from the development of thin wideband antireflective (AR) surfaces. Here, we incorporate magnetic materials into AR gradings using two approaches. 1) We use the analytic approach demonstrated in a recent paper that details an optimal wideband AR design using a continuous one-dimensional (1-D) grading of dispersive dielectrics [1]. We extend the dispersive nonmagnetic equations in [1] to design perfect AR magneto-dielectric gradings. 2) We derive a spatial-coordinate transformation (SCT) approach that transforms the nonmagnetics solution to achieve a perfect AR magneto-dielectric grading. We find, in general, that the SCT method enables more realizable and flexible solutions. We detail a practical approach for realizing the magneto-dielectric gradings using subwavelength texturing (i.e., motheye method). Several numerical examples demonstrate the utility of this approach in realizing very thin, yet broadband, and AR designs.