Metamaterial-inspired absorber for GNSS and 5G pioneer spectrum band: Achieving narrow bandwidth, wide incidence angle, and polarization agnostic

The recent emergence of electromagnetic (EM) metamaterial absorbers (MAs) with exceptionally high absorption rates has captured the interest of numerous researchers. This study introduces an innovative design for a dual-band microwave absorber, inspired by metamaterial concepts. A square ring resonator, a second ring resonator with splits at each of its four corners, and a third ring resonator created by joining two I-shaped pieces make up the unit cell, which has the dimensions $25.5\times 25.5\times 2.54{\mathrm{mm}}^3$. These resonators are realized on a metal-backed FR-4 substrate, a common dielectric material found in printed circuit boards. The primary objective of this absorber's configuration is to achieve remarkable absorption peaks at 1.55 GHz and 3.3 GHz, attaining absorption levels of 99.73% and 99.41%, respectively. Notably, the design is insensitive to polarization and exhibits a broad incidence angle of up to 60°. It maintains high absorption rates of 95% for the transverse electric mode and 94% for the transverse magnetic mode. In order to optimize the suggested design, parametric studies were carried out for unit cell design by varying the split gap, loss tangent, and various types of metal. The advanced design system (ADS) software was used to assess an equivalent circuit, and the results of the CST simulation were compared with the circuit, confirming good agreement. These attributes are well-suited for efficiently absorbing signals within specific frequency ranges, catering to the demands of applications such as Global Navigation Satellite Systems (GNSS) and the pioneering 5G frequency band. Simulation and measured results of the absorber closely align with the expected performance, affirming the efficacy of the design. In essence, this solution provides an effective means of absorbing electromagnetic waves in these defined frequency ranges, rendering it highly suitable for diverse wireless communication and navigation systems.