Microwave Absorption Properties of Double-Layer RADAR Absorbing Materials Based on Doped Barium Hexaferrite/TiO2/Conducting Carbon Black

In this report, we demonstrate microwave absorption properties of barium hexaferrite, doped barium hexaferrite, titanium dioxide and conducting carbon black based RADAR absorbing material for stealth application. Double-layer absorbers are prepared with a top layer consisting of 30% hexaferrite and 10% titanium dioxide while the bottom layer composed of 30% hexaferrite and 10% conducting carbon black, embedded in chloroprene matrix. The top and bottom layers are prepared as impedance matching layer and conducting layer, respectively, with a total thickness of 2？mm. Microwave absorption properties of all the composites were analyzed in X-band region. Maximum reflection loss of ？32？dB at 10.64？GHz was observed for barium hexaferrite based double-layer absorber whereas for doped barium hexaferrite based absorber the reflection loss was found to be ？29.56？dB at 11.7？GHz. A consistence reflection loss value (>？24？dB) was observed for doped barium hexaferrite based RADAR absorbing materials within the entire bandwidth. 1. Introduction In the recent years, X-band RADAR application increases in military sector due to its high precision target detection capability. Keeping it in view, microwave technology advancement is forced to focus on the development of efficient RADAR absorbing materials (RAMs) for applications in the field of stealth technology [1] and electromagnetic (EM) shielding. Therefore, there is a demand for effective microwave absorbing materials for wideband applications. RADAR wave in the form of EM energy can be completely or partially absorbed and dissipated into the absorbing materials through magnetic and dielectric losses. The phenomenon of the absorption is prominent if characteristic impedance of the free space is equal to the characteristic impedance of the absorber. Efficient RAMs can be prepared with materials which allows EM wave to penetrate easily and attenuate whole of the electromagnetic energy within itself [2]. Ferrites based RAMs show interesting behavior in X-band frequency range and have been used in the form of sheets, films, paints, and ceramic tiles. Hexagonal barium hexaferrite and doped barium hexaferrite are suitable candidates to be used to develop composite RAMs due to their good permittivity and permeability value within X-band region. Gairola et al. [3] reported a maximum reflection loss of ？14.7？dB for 2？mm thick single-layered RAMs based on barium hexaferrite and Co, Mn, and Ti substituted barium hexaferrite. Qiu et al. [4] reported a nanocomposite multilayer absorber film using barium hexaferrite (BaFe12O19) and