Design and experimental performance analysis of a low-profile dual-band microwave absorber

This work investigates the design and experimental analysis of a compact dual-band absorber (DBA) for polarization-independent wideband operation in both the X and Ku bands. The proposed absorber unit-cell consists of inverted flag-shaped elements arranged in four quadrants and four edge-touching rectangular patches, with a square patch at the center on its top level. The bottom ground plane is a continuous metal plate, while a 1.6 mm thick FR4 substrate separates the top and bottom components. The full-wave simulation results exhibit a wide absorption response, with absorptivity exceeding 90% for all polarization angles under normal incidence. The dual bandwidth can be controlled by tuning the structural parameters. A prototype of the DBA was tested, and its measured outputs aligned well with the full-wave simulations. The proposed DBA offers outstanding merits, such as a thin single-layer configuration, no air gap, reduced lumped resistors, enhanced absorption bandwidth, and polarization insensitivity.