Mitigation in broad band microwave shielding properties of Ni-Co/NC composite

Abstract

It is tactically important for a high-resolution seeking tracker to generate clutter, greatly facilitated by electromagnetic interference shielding. Nickel-Cobalt /Nano?carbon (Ni-Co/NC) composites are synthesized by a simple, solid-state combustion method. The scattering performance of Ni-Co/NC composites is reported over the frequency range of 2�18 GHz with varying equal weight % of Nickel and Cobalt from (5 to 25)% and characterized using X-ray diffraction, Fourier transform-infrared spectroscopy, Energy Dispersive X-ray spectroscopy, and Scanning Electron Microscope technique. Additionally, fabricated toroidal specimens are examined for reflection loss measurements. According to analysis, the phases NiO and NiCo2O4 are formed when nickel and cobalt are added to nano?carbon. These phases subsequently diffuse throughout the nano?carbon network to produce the Ni�O stretching vibration modes, O-X-O and X-O-X (where X = Ni or Co) modes. Asymmetric polarization at low nickel?cobalt weight % changes to symmetric polarization at higher weight % in the Ni-Co/NC composites. The analysis of constitutive parameters indicated a hybrid ac conductivity behaviour (Debye- and Jonscher-like), an increase in complex permittivity and permeability, and a variation in synergetic magneto-dielectric coupling energy with frequency. Additionally, the characteristic impedance and skin resistance have been calculated. In general, the 20-wt% Ni-Co/NC composite exhibits the highest absorption at 7.28 GHz at 3.85 mm of thickness at low frequency. However, over a higher frequency range, the 5-wt% Ni-Co/NC composite exhibits a high-performance shield design, achieving ?21.05 dB reflection loss at a thickness of 5.45 mm with 2.24 GHz of effective bandwidth. � 2023 Elsevier B.V.