With the demand for larger bandwidths and faster data speeds, wireless communication systems are expanding into the millimeter wave and terahertz region of the electromagnetic spectrum. Successful transition to higher frequencies, particularly for systems located in urban or indoor environments, will require a thorough understanding of the reflection, transmission, absorption, and scattering of a wide variety of materials. For this study, the co-polarization and crosspolarization backscattering coefficients of several dielectrics were measured in compact radar ranges operating from 160 GHz to 1.55 THz. These structures consisted of dielectric disks with various rough surfaces. The backscattering measurements of these disks were compared as a function of polarization, incident angle, roughness, and frequency.