In this thesis, we study the use of lenses to improve the performance of massive multiple-input multiple-output (MIMO) full-duplex base-stations operating in 3.5 GHz Citizens Broadband Radio Service (CBRS) band.We experimentally demonstrate that practical lens designs can reshape the beam patterns of the antenna array to improve the “focus” of the main lobe while reducing the power in the side lobes. The reduced side lobe power translates into reduced self-interference and hence im- proved capacity of the full-duplex systems that use precoding to manage self-interference. Our results show that an additional 3.5-15 dB of self- interference can be cancelled using large lenses without compromising the downlink receive power. The reduced self-interference provides a spectral efficiency gain of up to 4 bits/s/Hz in the uplink and 6 bits/s/Hz in the downlink communication of large lens-based full-duplex system.