Md. Murad Nipun, Md. Jahedul Islam
This work presents a wideband metamaterial absorber (MMA) specifically designed for electromagnetic shielding and energy harvesting within the GSM and 3G communication frequency range. The proposed structure is based on a resistively loaded concentric octagonal ring configuration, where three symmetrically distributed octagonal rings integrated with lumped resistors enable broad and stable absorption. Simulation results confirm that the absorber achieves more than 90% absorption across 774 MHz to 2.2 GHz, fully covering the GSM 900, GSM 1800, and UMTS 2100 MHz bands. Within this band, three pronounced absorption peaks are observed at 980 MHz (98.34%), 1.67 GHz (99.1%), and 2.1 GHz (97.1%). The design demonstrates excellent average harvesting efficiency of 93.03% from 0.8 GHz to 2.1 GHz, and strong shielding effectiveness, measured as 41.31 dB, 42.71 dB, and 39.22 dB at the respective resonances. In addition, the absorber remains polarization- and angle-insensitive up to 60°, ensuring stable performance under practical operating conditions. To validate the physical mechanism, an equivalent circuit model was developed in ADS, showing close agreement with electromagnetic simulations. Experimental measurements also confirm the simulated results, highlighting the reliability of the design. The combination of wideband absorption, high efficiency, angular stability, and compact geometry establishes the proposed MMA as a strong candidate for GSM/3G electromagnetic interference shielding and ambient energy harvesting applications in wireless communication environments. Also, the present absorber is different from the earlier resistively loaded SRR and multi-ring structures by using a concentric octagonal layout together with an optimized pattern of resistive loading. The combination allows for closely spaced resonances to merge into a wide operating band, supporting both strong electromagnetic shielding and high harvesting efficiency within the same compact surface.