A Wide-Angle, Polarization-Insensitive, Wideband Metamaterial Absorber With Lumped Resistor Loading for ISM Band Applications

This work introduces a wideband metamaterial (MM) absorber designed to operate effectively across a wide reception angle and be polarization-insensitive within ISM band (2.4 GHz) applications. The proposed absorber unit cell comprises four copper sectors loaded with lumped resistors and a full copper ground plane hosted onto two FR4 substrates. Furthermore, an air layer suspended between the ground plane and a FR4 substrate is applied to achieve wideband absorption. In addition, the simulation results show that particular design factors, such as lumped resistors and unit cell geometry, can be optimized to improve the efficiency of the absorber. The simulations demonstrate that the proposed absorber achieves a wideband absorption, exceeding 90%, over a broad frequency range from 1.94 GHz to 2.98 GHz. The designed absorber was fabricated and tested, and the simulation and measurement results were agreed well.