Modeling of Silicon-Based Substrates of Patch Antennas Operating in the Sub-THz Range

The paper describes a convenient way to numerically model planar antennas dedicated to sub-terahertz (THz) radiation detectors while accounting for multiple oxide layers included in typical silicon-based substrates used in microelectronics. Several approaches are presented, including a solution based on calculations of effective permittivity of the layered substrate. The results suggest that this approach can work at lower frequencies, but will not be effective in the sub-THz range due to different mechanisms of dispersion occurring in transmission lines with either homogeneous or layered substrate. Therefore, an alternative approach based on anisotropic layers has been proposed, which proves to be efficient and easy to adopt in typical numerical models. It also explains well the results of experiments done using a set of patch antennas fabricated on thin membranes and operating at various frequencies from 240 GHz up to 370 GHz.