Low-Profile and Wideband Paper-Based Honeycomb Microwave Absorber With Capacitive Loops

A low-profile and wideband paper-based honeycomb microwave absorber is proposed and analyzed. The absorber is constructed using capacitive loops loaded with interdigital capacitors. To demonstrate the advantage of capacitive loops in reducing thickness, an absorber with inductive loops is also designed for comparison. Leveraging the capacitance properties of the loops, a wideband absorbing response (2.24–18.7 GHz, 157%) is achieved with a small electrical thickness of approximately 0.12 wavelengths at the lowest operating frequencies, which is 33.3% less compared to the inductive loop-based absorber. The absorbers are fabricated and measured in terms of electromagnetic (EM) and mechanical performances. Besides of the achieved wideband absorption, the proposed absorbers feature lightweight (with densities of approximately 15–16.6 kg/m<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">³</i>) and load-bearing properties (the compressive strength is around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma \,\, =0.25$ </tex-math></inline-formula>–0.29 MPa).