Ba(Co,Zn)₂-W type hexagonal ferrites, prepared by a citrate sol–gel method have been used as fillers in five layers of chlorosulphonated polyethylene matrix composite. Adding an outer layer with carbonyl iron filler, a thin quasi-double-layer microwave absorber has been fabricated, that exhibits reflection loss (RL)<−12dB at 5–12GHz with a broad minimum of −18dB at 7.5–9.5GHz. Layer succession has been optimized for 2mm total thickness and minimum RL at the X-band, by means of a model based on the transmission line theory, with the actual permittivity ε and permeability μ of the layers as input parameters. This approach has permitted the optimum use of hexagonal ferrites with varying electromagnetic properties.