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We present a topology for suppressing quantization lobes in 1-bit reconfigurable reflective surfaces (RRSs). RRSs are planar surfaces that redirect the imping waves to the desired direction through phase modulation. For single-bit modulation, plane-wave illuminated RRSs exhibit quantization lobes due to the limited number of available phase bits. To eliminate such lobes, we randomize the quantization error by employing a fixed but random phase delay in every unit-cell of the RRS. Specifically, we focus on the fabrication and characterization of a mmWave single-layer, 1-bit, 30×30 randomized RRS designed at 222.5 GHz. The quasi-optical RCS characterization of the fabricated RRS demonstrates the successful suppression of the quantization lobe using the proposed technique. 

We investigate the propagation losses in terahertz (THz) non-line-of-sight (NLoS) imaging and compare the performance to the optical counterpart. NLoS imaging exploits the multiple reflections of electromagnetic waves from surrounding surfaces to reconstruct the geometry and location of hidden objects. THz and visible/infrared radiations are attractive for NLoS imaging due to the short wavelengths and practical apertures that can support this non-conventional imaging. However, the scattering mechanisms vary significantly and determine the quality of the reconstructed images. This work compares for the first time the free-space path loss and rough surface scattering losses of a simple THz and optical NLoS imaging topology. Because specular reflections are dominant in THz scattering while optical systems suffer from strong diffuse scattering, THz NLoS imaging systems can receive considerably stronger backscattered signals.