Efficient Optimization Design Method for Ultra-Wideband Absorber Utilizing Frequency-Dispersive Paper-Composites

This work presents a novel design method for ultra-wideband absorbers using frequency-dispersive materials. In this method, a characterization model for permittivity is constructed and then integrated with a modified genetic algorithm for further optimization. Firstly, a carbon nanotube (CNT) doped paper composite (PC) is presented, which exhibits obvious frequency-dependent dielectric loss characteristics. The composite is then incorporated into a periodic-plate array (PPA), thereby enabling flexible adjustment of the effective permittivity. Secondly, a Beta-distribution mathematical model is proposed to characterize the frequency-dependent permittivity of the PC-loaded PPAs. The model is then integrated with a genetic algorithm, offering an efficient approach for determining the optimal permittivity of materials in a multilayer absorber, thus achieving ultra-wideband absorption at a specific thickness. For demonstration, a three-layered absorber is designed and then fabricated using the presented CNT-doped composites with sheet resistances of $100\Omega $ /sq and $150\Omega $ /sq. The designed absorber has an absorption band (RL<−10dB) from 1.56 to 18 GHz (168%) with a thickness of 31mm ( $0.16{\lambda }_{\mathrm { L}}$ ). The simulated and measured results exhibit good agreement, validating our proposed method.