Exploring the Effectiveness of Thin Microwave Absorber Applied in Parallel-Plate Waveguide

This work explores the effectiveness of the conventional thin microwave absorber (MA) applied in the parallel-plate waveguide (PPWG). The simulation results reveal that, the MA designed for absorbing the normally incident wave in the free space also suits the PPWG application when the thickness of the PPWG
$t\leq 0.25\lambda_{0}$
. A segment of the MA with 0.5
$\lambda 0$
length could bring
$\sim 10\text{dB}$
electromagnetic interference (EMI) suppression in the PPWG with
$t\sim 0.25\lambda 0$
, at the designed working frequency of the MA. While in the thin PPWG
$(t < 0.25\lambda_{0})$
, the MA exhibits larger EMI suppression magnitude and bandwidth. Based on these discoveries, the MA design difficulties for the practical engineering scenes, such as multi-layered printed circuit boards and high-speed circuits' packages, are discussed to provide a valuable reference.