Principle of FMCW radar

This document discusses the principles and signal processing techniques of Frequency-Modulated Continuous-Wave (FMCW) radars, focusing on linear FMCW radar for precipitation measurements. It explains the modulation process that enables ranging capabilities, Doppler frequency shifts related to moving targets, and provides an overview of the IDRA drizzle radar system developed at the Delft University of Technology. The document includes specific technical specifications and a block diagram of the radar system, emphasizing its applications in atmospheric remote sensing. 

principle-of-fmcw-radarsfrom tobiasotto

Principle of FMCW radar by Tobias Otto, TU Delft

Principle of FMCW radar from tobiasotto

High-Resolution Observations of Insects in the Atmospheric Boundary Layer

High spatial and temporal resolution S-band radar observations of insects in the atmospheric boundary layer (ABL) are described. The observations were acquired with a frequency-modulated continuous-wave (FMCW) radar during the 2002 International H₂0 Project (IHOP_2002) held in Oklahoma in the months of May and June 2002. During the observational period the boundary layer was convective with a few periods of rain. Rayleigh scattering from particulate scatterers (i.e., insects) dominates the return; however, Bragg scattering from refractive index turbulence is also significant, especially at the top of the afternoon boundary layer. There is a strong diurnal signal in the insect backscatter: minima in the morning and at dusk and maxima at night and midafternoon. Insect number densities and radar cross sections (RCSs) are calculated. The RCS values range from less than 10⁻¹² m² to greater than 10⁻⁷ m² and likewise have a strong diurnal signal. These are converted to equivalent reflectivity measurements that would be reported by typical meteorological radars. The majority of reflectivity measurements from particulate scatterers ranges from −30 to −5 dBZ; however, intense point scatterers (>10 dBZ) are occasionally present. The results show that although insects provide useful targets for characterization of the clear-air ABL, the requirements for continuous monitoring of the boundary layer are specific to time of day and range from −20 dBZ in the morning to −10 to −5 dBZ in the afternoon and nocturnal boundary layer (NBL).- Reference