Complex permittivity, complex permeability and reflection loss of Co-Zr substituted La-Sr hexaferrites in 18-40 GHz frequency range

In this research, electromagnetic and microwave absorption properties of the hexagonal ferrites with chemical composition, Sr0.85La0.15(CoZr)(x)Fe12-2x O-19 (x = 0.00, 0.25, 0.50, 0.75 and 1.00) were studied in the K-band (18-26.5 GHz) and Ka-band (26.5-40 GHz) frequency range. Minimum reflection loss (RL) was successfully optimized in the studied frequency range by tuning sample thickness using quarter-wavelength criterion. Absorption results of synthesized hexagonal ferrites show minimum RL in the range of -18.15 dB to - 28.69 dB and absorption bandwidth ( -10 dB) in the range of 1.04 GHz to 5.87 GHz. The microwave absorption significantly improved with absorption bandwidth ( -10 dB) of 5.87 GHz for the composition x = 1.00 at a sample thickness of 2.2 mm. These newly synthesized ferrites have high potential as microwave absorbing material for military applications such as camouflaging of the target and also as EMI (Electromagnetic Interference) suppressor.