(color online) (a) Unit cell of the perfect absorber based on resistance film, the parameters are shown as follows: a = 1.8 mm, b = 2.6 mm, w =1.2 mm, θ =45°, P = 10 mm, h = 3 mm, ε_r = 1.4, and the surface resistance of the branch structure . (b) Fabricated sample of the lightweight perfect absorber, and (c) the absoption spectra for different incident angles.^[142]