  Increasing attention on microwave ultra-broadband metamaterial absorbers has
been paid due to their promising applications. While most microwave
ultra-broadband metamaterial absorbers developed so far are based on metallic
resonant structures, dispersive dielectric water-based metamaterial opens a
simpler and more versatile route for the construction of polarization- and
angle- insensitive ultra-broadband absorption. Here, we review the recent
progresses of water-based metamaterial absorber by providing an illustration of
the mechanisms to realize ultra-broadband, tunable and multi-functional
absorption. We also address the further development direction and some
potential novel applications.
