  Over the past decades, many radome designs to extend the angular scan range
of phased-array antennas have been devised by utilizing dielectric materials
and metamaterials. More recently, metasurface technology such as planar lenses
and beam deflectors have been applied to phased arrays, enabling scan-angle
enhancers to have a low profile. In this work, a physical Huygens' metasurface
(HMS) two-lens system for scanangle doubling of a phased array is presented.
For the HMS unit cells, the wire-loop topology is deployed to achieve high
transmission for the required phase-angle shift. The proposed two-lens system
is analyzed by full-wave simulations and experiments. The simulation results
demonstrate that the scan angle doubles when the incident angle is below
15{\deg} in accordance to the design specification. Furthermore, the
directivity degradation of the refracted beams by the two-HMS lenses is in good
agreement with theory. Finally, a fabricated two-lens system with two
15{\lambda} long by 15{\lambda} wide metasurface lenses and a
16{\times}16-element patch antenna array as a source is experimentally verified
at 10 GHz. The experimental results are in good agreement with the simulated
results by showing angle-doubling performance with {\pm}2{\deg} scan errors.
