We propose, investigate and demonstrate a pure and simple dielectric probe operating in the sub-THz range with an example band of interest 190-220 GHz. High-resistivity silicon technology is deployed for this non-TEM mode probe development as it presents a viable low-loss material. A T-shape alignment dowel was used to integrate the silicon probe with the waveguide block. The probe can be used to measure and characterize the low permittivity-based dielectric waveguide transmission line and its building components free from the use of any transition structures and TEM-mode probes. For demonstration, the silicon probe was used to measure a substrate integrated image guide and its components in the range of 190-220 GHz. A substrate integrated image guide (SIIG) based TRL calibration kit was developed, and a two-tier TRL calibration was used to characterize the SIIG.