Estimation of wind turbine radar signature at 13.5 MHz

The radar cross sections (RCS) and frequency spectra of a wind turbine consisting of three conducting blades of 42 m radius, with a vertical mast of 65 m over a perfect ground plane, was estimated using the Numerical Electromagnetics Code (NEC). The NEC input deck generation, parsing the NEC output to select the RCS numbers, plotting the time series, and calculating and plotting the frequency spectra were all done by bash shell scripts. The shell scripts generally set up several environment variables and then called Ruby, Octave or Gnuplot programs to perform the text manipulations, data calculations and plot generation. Calibrated plots of time series and frequency spectra for several cases are included. The effect of a dielectric blade is briefly considered.