Metasurfaces (MS) have recently attracted a lot of attention due to their
ability to manipulate electromagnetic characteristics. The metasurface
is constructed from two-dimensional scatterers (metallic and dielectric)
which provide simplicity in fabrication and flexibility for integration
with other systems. The metallic metasurface unit cells and dielectric
metasurface unit cells have a length of sub-wavelength.Most essential
ideas of metasurfaces are directly borrowed from antenna array theories
such as reflectarray and transmitarray. On the other hand, progress in
metasurfaces has aided and accelerated the development of antennas.
Metasurface can be used to achieve an increase of the gain of antenna
depending on the hyperbolic phase distribution of the metasurface unit
cell which constructs the focusing metasurface. Also, the metasurface
can be used to achieve RCS reduction, mutual coupling reduction,
frequency scanning, multibeam generation, and end-fire antenna.