  We present the design, numerical simulations and experimental measurements of
THz metamaterial absorbers with a broad and flat absorption top both for
transverse electric and transverse magnetic polarizations over a wide incidence
angle range. The metamaterial absorber unit cell consists of two sets of
structures resonating at different but close frequencies. The overall
absorption spectrum is the superposition of individual components and becomes
flat at the top over a significant bandwidth. The experimental results are in
excellent agreement with numerical simulations.
