Polarization-Insensitive Optically Transparent Microwave Metamaterial Absorber Using a Complementary Layer

A simple optically transparent absorber based on a double complementary structured layer of the indium-tin-oxide (ITO) deposited polyethylene terephthalate film is presented. The structure showed more than 90% absorption from 2 to 4.5 GHz of the frequency with a thickness of 0.0847
$\lambda _L$
(wavelength corresponding to the lowest frequency of absorption band). The computed absorptivity of the proposed structure is validated using the transmission line theory and measured experimentally as well. The structure has polarization-insensitive response and is highly stable for the oblique wave incidence over a wide angular range. This absorber can be conformally wrapped on a curved surface and reduces the radar cross section (RCS) by more than 10 dB of a curve cylinder. This 10 dB RCS reduction covers almost the entire S-band of microwave frequencies. Optical transparency and flexibility of the proposed absorber make it suitable for a wide range of applications.