Miniaturized metamaterial absorber based on a high permittivity substrate

摘要

Electromagnetic metamaterial absorbers are an efficient replacement for the conventional absorbers due to their advantages like compact thickness, user control of frequency, etc. This work explores the development of a metamaterial absorber using a specifically synthesized substrate. Compared with commercially available substrate boards, a thoroughly designed substrate provides additional control over the absorber properties as it can have a dielectric constant and loss tangent of choice. This paper introduces a novel ceramic, Ba_3Fe_(10)Ti_(18)O_(54) (BFT), as a substrate for a metamaterial absorber having permittivity, ε_r ～ 22.3, at X-band frequency. The high dielectric constant results in a miniaturized metamaterial absorber with the dimensions λ/8 × λ/7 × λ/28. The proposed absorber produces 97.4% absorption at 10.65 GHz, which is studied numerically and experimentally. Absorption above 90% for the proposed structure has a bandwidth of 0.75 GHz. The broad nature with a simple topological structure can be attributed to the presence of dielectric and magnetic loss in the substrate. The absorption mechanism is explained with impedance and surface current analysis. Further, absorption characteristics are analyzed with the different thicknesses of the substrate.