Ka band absorption properties of substituted nickel spinel ferrites: Comparison of open-circuit approach and short-circuit approach

Abstract

This paper presents the electromagnetic and absorption properties of Co and Co–Mn–Zr substituted Nickel spinel ferrites in Ka-band (26.5–40 GHz). A novel comparison of two commonly used absorption analysis approaches, open-circuit and short-circuit, is also presented. Electromagnetic properties such as complex permittivity and complex permeability of the studied NC (Ni–Co) and MZ (Ni–Co–Mn–Zr) series ferrites show almost steady response to frequency in the studied frequency band. For open-circuit absorption analysis, ferrite pellets of particular dimensions (WR-28 waveguide) were prepared to determine experimentally reflection loss and transmission loss values. Variation of absorption properties with respect to sample thickness is determined by manually reducing the thickness. Composition MZ 6 has turned out to be the best absorber with an effective absorption of around 75%. To obtain absorption results in short-circuit approach, reflection loss values are simulated using back metal-plate method. Composition NC 0.90 shows the best absorption results out of the analyzed compositions with RL peak of -36.67 dB at 31.36 GHz and -10 dB absorption bandwidth of 9.5 GHz in this approach. Both the analyses are compared to find out the application areas of each approach. The overall absorption analysis proposes the studied ferrite compositions for possible applications in electromagnetic wave interfernece (EMI) reduction in Ka-band.