An electromagnetic energy absorber comprising a thin electrically-conductive ground plane as a base. Dielectric layers are positioned over the ground plane and high impedance surface (HIS) as a top layer. The impedance layer can be formed by loading the lumped resistor to a metallic grating like an FSS (Frequency Selective Surface). An air-spacer between the substrates has replaced the problem of the large electrical thickness of the substrate with effective permittivity. Metamaterial structures enable control over the resonant frequencies, and performance is enhanced over a broad frequency band. In addition, two broadband reflective-type linear to orthogonal polarization converters are disclosed that provide improved bandwidth and angular stability performance.