BROADBAND RF-WAVE ABSORBER DESIGN USING COMPOSITE MAGNETIC MATERIAL

Rastislav Dosoudil – Marianna Ušáková – Elemír Ušák – Jaroslav Franek – Jozef Sláma

   The composite material based on ferrite powder filler of composition Ni_0.276Zn_0.644Cu_0.08Fe₂O₄ and diamagnetic polymeric PVC matrix has been prepared and then used to the design of a grid.shaped EM.wave absorber for the quasi.microwave frequency range (1 MHz - 3 GHz). The bandwidth of the designed absorber was controlled by an air cavity rate (K). Using a synthesized capacitance and inductance model, the complex equivalent permittivity and permeability were calculated as a function of K. The single-layer EM.wave absorbing characteristics of the designed absorber were investigated in the frequency range concerned and selected absorption parameters such as return loss (RL), matching frequency (f_m), matching thickness (d_m), and bandwidth (Δf) for RL ≤ - 15 dB were estimated by means of computer simulations (in the MATHCAD environment). Decreasing of permittivity and permeability, and simultaneously increasing of bandwidth of the EM.wave absorber have been achieved with the raise of K. The designed RF absorber may be utilized in the applications such as EMI (electromagnetic interference) reduction in portable radio communication and/or IT (information technology) equipments.

Keywords: permittivity, permeability, composite material, return loss, bandwidth, matching thickness, grid-shaped absorber

[full-paper]