  The smartphone, as a media device, should offer a large-size screen and fast
data rates in a well-packed device. Emergent 5G technologies based on
millimeter waves need efficiently radiating antennas integrated into devices
whose bodies (especially glass screens) behave as waveguides in the antenna
frequency bands. Using the concept of retroreflective surfaces, this work
proposes a compact metasurface located below the smartphone glass screen which
reduces surface-wave excitation and propagation, and significantly improves the
radiation pattern and efficiency of millimeter-wave antennas integrated into
mobile terminals.
