Investigation of microwave absorption properties of ferrite added composite materials

Stealth or low visibility technology has become a critical requirement in military aviation as radar systems have become increasingly advanced. Radar is an electromagnetic system that tracks moving objects. Microwave absorbing materials are used both in military applications to reduce radar signature and in civil applications such as electronics and telecommunication systems to reduce electromagnetic wave pollution. In this thesis, epoxy matrix carbon nanotube (COOH-MWCNT) and various ferrite reinforced (Ni0.5Zn0.5Fe2O4, BaFe12O19, ZnFe2O4) composites were produced by hand lay-up method. Samples containing 0.5, 1.5 and 3 wt% carbon nanotubes were produced. In addition, composites containing 50 wt% of various ferrites and varying carbon nanotube ratios of 0.5, 1.5 and 3 wt% were produced. The microstructures of the produced samples were examined by scanning electron microscopy. As a result of scanning electron microscopy, the distribution of carbon nanotubes and various ferrite powders in the epoxy matrix and the homogeneity of the structure were examined. In addition, electromagnetic tests such as dielectric permeability and magnetic permeability, dielectric tangent loss and magnetic tangent loss and reflection measurements were applied to the samples in the X-band range. High and low temperature tests were performed to investigate the temperature dependent changes in the electromagnetic properties of the samples and their usability as absorbing materials was investigated. The reflection measurement of CNT1.5, FCNT1.5 and FCNT3 samples, together with the results of thickness optimization high and low temperature reflection measurement, showed that the CNT1.5 sample offers wide operating frequency and is suitable for use as an absorbing material. It is concluded that the FCNT3 sample with nickel zinc ferrite shows better electromagnetic properties in them compared to the FCNT3 sample with zinc ferrite and barium hexaferrite doping.