  Ultrawide-angle electromagnetic wave absorbers with excellent mechanical
properties are required in many diverse applications such as sensing, and
stealth technologies. Here, a novel 3D reconfigurable metamaterial absorber
(MMA) consisting of honeycomb and VO2 films is proposed. The proposed MMA
exhibits a strong absorptivity above 90\% in the widest incident angle up to
$87^\circ$ for TM- and TE- polarized oblique incidences for THz wave
propagating in yoz-plane. According to simulation results, under normal
incidence, when VO2 films are in the insulating state, the proposed absorber
exhibits high absorptivity in the frequency band of 1-4 THz. By increasing the
temperature of the whole structure, the structural transformation of VO2 occurs
and turns into the metallic phase. We have shown that under oblique incidence,
the ohmic losses of VO2 films especially those parallel to the direction of the
incident electric field are the most important absorption principles of the
proposed MMA. Furthermore, to understand the physical mechanism of absorption,
the induced electric field as well as the power loss density of the proposed
structure are investigated. In addition, it is shown that the presented VO2
based honeycomb absorber retains its full-coverage incident angle
characteristics for TM-polarized incidences propagating in the xoz-plane. Due
to the ultra wide-angle absorption (angular stability) and mechanical
performance, it is expected that the presented MMA may find potential
applications, such as camouflage technologies, electromagnetic interference,
imaging, and sensing. To the best knowledge of authors, the proposed MMA
configuration exhibits the absorptivity in the widest incident angle ever
reported.
