Use of dielectric inhomogeneous planar layers as optimum microwave absorbers

Dielectric inhomogeneous planar layers (IPLs) are optimally designed as microwave absorbers in a desired frequency range and incidence angle range. First, the lossy electric permittivity function of the IPL is expanded in a truncated Fourier series. Then, the optimum values of the coefficients of the series are obtained through an optimisation approach. The performance of the proposed structure is investigated and verified using two examples in the frequency range 8-12-GHz and 6-18-GHz.