Bistatic Radar Geometry for Maximisation of Radar Cross Section of an Unmanned Aerial Vehicle

Due to their reduced size and usual complex design, detection and tracking of commercial off-the-shelf (COTS) Unmanned Aerial Vehicles (UAVs) is a challenging task. It is often the case that the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$UAV$</tex> under test backscatters the impelling radiowave in a different direction than where the transmitter is, thus reducing the received signal strength for the monostatic case. By making use of spatial diversity, for some specific ge-ometries Bistatic radar systems may improve the detection probability by increasing the measured radar cross-section <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(RCS)$</tex> of targets with low monostatic <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$RCS$</tex> signature. This study examines the backscattering properties of a selected COTS UAV for monostatic and bistatic radar configurations. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$RCS$</tex> of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$UAV$</tex> 's airframe components, along with their material properties, was calculated and simulated to estimate their contributions to the overall backscattered energy. Simulations were performed at C- (5.8 GHz) and Ka-band (34 GHz) to evaluate <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$RCS$</tex> variations across a full azimuthal sweep <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(0^{\mathrm{o}}\ to\ 360^{\mathrm{o}})$</tex>. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$UAV$</tex> was modeled as both composite and perfect electric conducting <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(PEC)$</tex> materi-als. The simulated results were validated by using the monostatic configuration and the theoretical <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$RCS$</tex>,” based on the approximation of canonical shapes of the UAV's diverse airframe components. Results showed a significant <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$RCS$</tex> enhancement for the selected bistatic geometries, particularly in the forward scatter region. As expected, the forward scatter region showed little to no dependence on the material properties. At 5.8 GHz, <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$a$</tex> wider forward scatter region was observed due to the longer wavelength. In comparison, a narrower forward scatter region was observed at 34 GHz due to shorter wavelengths while maintaining the same target dimensions.