Transparent conformal metasurface absorber for ultrawideband radar cross section reduction

Flexible metasurface (MS) based absorbers have gained significant importance in recent years due to their possible use in non-planar radar stealth applications, however, their narrow bandwidth and insensitivity to incidence angles limit their potential use. In this work, we present an ultrawideband and angular insensitive MS absorber based on indium tin oxide (ITO), polyethylene-terephthalate, and polyvinyl chloride, that is both transparent and flexible. Broad-spectrum absorption can be maximized by using ITO with modest sheet resistance upon interaction with electromagnetic (EM) waves. To further validate the absorption performance, the radar cross section (RCS) characteristics are investigated. The results indicate that over 10 dB RCS reduction is realized across an ultra-wide frequency range of 13.30-39.76 GHz, with relative bandwidth up to 100% for planar MS under linearly and circularly polarized incidence EM waves. Furthermore, the RCS reduction performance of an MS is well maintained in the abovementioned frequency band when it is bent with various bending angles. The proposed MS is a promising contender for practical applications in microwave stealth technology due to its additional advantages of visible transparency, mechanical flexibility, low profile, wide-angle stability, and polarization insensitivity.