An Experimental Characterization of Atmospheric Turbulence Effects on Millimeter Wave Propagation in a Controlled Environment

Citation

Sheng, Shawn JiaXiang (2026) An Experimental Characterization of Atmospheric Turbulence Effects on Millimeter Wave Propagation in a Controlled Environment. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/7sbc-5v10. https://resolver.caltech.edu/CaltechTHESIS:11262025-191857258

Abstract

Atmospheric turbulence significantly affects electromagnetic (EM) wave propagation, especially at millimeter-wave (mmWave) frequencies, resulting in scintillation. Developing a statistical channel model to characterize these effects is crucial for accurate prediction and mitigation across various applications. In radar and satellite systems, turbulence can degrade signal quality and reduce accuracy. As telecommunications advance toward higher EM frequencies, turbulence will significantly influence signal performance. Moreover, statistical analysis of a propagating EM wave provides a unique opportunity for the remote sensing of atmospheric turbulence dynamics. The push towards an improved understanding of the planetary boundary layer on a global scale motivates the development of next generation measurement techniques.

This thesis presents a novel approach for studying and characterizing the physical effects of atmospheric turbulence on mmWave propagation in a controlled laboratory environment. The method combines theoretical modeling and experimental validation to link meteorological parameters and turbulence dynamics to the scintillation effects on the power spectrum of a radio frequency (RF) signal. The experimental setup employs a versatile fan array wind tunnel to generate repeatable and controllable turbulent flows. A W-band (95GHz) transceiver is used to propagate EM energy through the turbulent flow, with the received signal analyzed to characterize the effects of turbulence-induced scintillation. Additional components include utility heaters for generating strong temperature gradients, a thermal screen and infrared camera to measure the temperature profile of the flow with high spatial resolution, a high-speed anemometer for turbulence spectrum characterization, and barometers and hygrometers for pressure and humidity measurements.

The effects of temperature gradients and wind speeds are shown to increase and shift the power spectrum of the RF signal across multiple turbulent scales. Meteorological and RF measurements are directly linked through an empirical model that builds upon existing theoretical frameworks to accurately determine flow dynamics based on the characteristics of the received signal. The results are shown to be consistent and repeatable across multiple days, ambient conditions, and experimental configurations. Improvements and future directions are discussed, including extending this experimental setup to practical applications and leveraging the controllability to develop more sophisticated models that advance the understanding of scintillation.