Conical Relief Structures for Expanding Operating Bandwidth of Ferrite

In this paper, an antireflective matching layer for ferrite is designed, consisting of a two-dimensional periodic array of conical. The gradient refractive index is achieved by increasing the area share of material and air at the same height, which over-comes the limited choice of materials for matching the impedance of neighboring dielectrics. Compared with the conventional quarter-wavelength matching method, the proposed conical structure can significantly increase the bandwidth (the reflection coefficient -20 dB relative bandwidth is about 53 %), realizing broadband operation. Due to the symmetry of the structure, the structure can operate with arbitrary polarization wave incidence.