Printed Quarter-Wavelength Absorber Using Carbon Nanotube Ink

In this paper, a quarter-wavelength absorber composed of printed resistive and reflective sheets is realized. The sheet resistances are 342 and
$0.5 \Omega/\text{sq}$
. using 1.7 times diluted carbon nanotube ink and silver copper ink. The wave absorber with −20 dB fractional bandwidth of 17% at the center frequency of 19.7 GHz is fabricated. The lightfastness characteristics of the fabricated wave absorber are also evaluated for outdoor use scenarios and the change of the fractional bandwidth was less than 2%.