Ultrawideband Microwave Absorber Conformable on Nondevelopable Curved Surfaces Based on the Hauberk Structure

In this article, we propose a low-profile and ultrawideband microwave absorber that is nondevelopable curved surface conformable, polarization insensitive, and wide-angle incidence insensitive. The absorptivity of the absorber is greater than 90% in 1.27–18.75 and 1.3–18.93 GHz for TE and TM mode vertical incidences, respectively. The relative absorption bandwidth is 174.6% and 174.3% both covering the entire S-, C-, X-, and Ku-bands. The absorber consists of a unique stainless-steel hauberk structure, a regular prismoid resistor sheet, and a three-layer square resistor sheet supported by polymethacrylimide (PMI) foam. Notably, the absorber’s thickness is only 0.093 times the highest operating wavelength at 1.27 GHz. In the 2–18-GHz band, the absorptivity is >80% for the TE mode within 60° incidence angle and >85% for the TM mode within an 80° incidence angle. When conformed to the surface of a standard metal sphere with a radius of 100 mm, the absorber demonstrated excellent nondevelopable curved surface conformability and achieved >5-dB radar cross section (RCS) reduction for both TE and TM mode incidence waves. This unique property makes the absorber ideal for applications with irregular and nondevelopable curved surfaces.