On the Design of Ultralow-Profile Broadband Absorber Based on Non-Foster Circuit
Cheng Zhang, Shaoqiu Xiao, Zhixin Yao, Zhiguo Jiang, Yan Li
Abstract
In this letter, a novel and effective method for non-Foster active absorber with ultralow profile and wide absorption band is proposed. The three-layer absorber consists of a square loop frequency selective surface array printed on the FR-4 dielectric substrate, a non-Foster matching layer, and a backed metal plane.Equivalent circuit model for the active absorber is proposed and analyzed, providing great insight into the effect of non-Foster matching layer on breaking the Rozanov limit effectively. A 1×10 absorber absorbing structure sample is fabricated.It is shown by measurement that the absorber has a fractional bandwidth of 36.0%, with a total thickness of only 0.008 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ<sub>L</sub></i> (wavelength at the lowest absorption frequency). The simulation and experimental results are in good agreement in the operating band, which verifies the accuracy of the design method.