Technical analysis and engineering reference.
As carrier frequencies rise above 100 GHz, wavelengths shrink to millimeters and sub-millimeters (e.g., 2.1 mm at 140 GHz; 1.3 mm at 220 GHz). At these minuscule scales, radio waves behave increasingly like light: diffraction around corners drops to near zero, surface roughness induces diffuse scattering rather than specular reflection, and free-space path loss is exceptionally severe (governed by the Friis equation).
To overcome high path loss, SubTHz arrays pack thousands of micro-strip patch elements into compact hand-sized form factors: - Rayleigh distance expands into dozens of meters, requiring transceivers to operate in the radiating near-field (Fresnel zone). - Beamforming matrices utilize spherical wavefront curvatures rather than traditional planar wave assumptions. - Depth-focusing beams delivering energy strictly to the spatial coordinates of the target terminal, eliminating interference to adjacent devices.
In aeronautical and high-velocity spaceborne applications, carrier frequencies in the hundreds of gigahertz produce colossal Doppler shifts (e.g., ±2.8 MHz Doppler at 140 GHz for vehicles moving at 6 km/s). SubTHz integrates phase-locked loop (PLL) pilot estimation tracking phase drift at 50 kHz refresh rates.