Geometrical and signal processing aspects using a bistatic hitchhiking radar system

Bistatic hitchhiking radar system concepts have been object for extensive research both for military and civilian applications. Hitchhiking systems are in principle easy to construct and can be used without introducing any interference, or being seen by a possible enemy. This paper addresses how to handle the geometry such systems are faced together with using proper signal analysis strategies for obtaining optimum target detection. The main motivation for doing bistatic measurements is to be able to see signals from the target that are scattered in other directions than backwards, due to target shape. For large bistatic angles the target forward scattering region can give serious enhancement due to the Babinet principle. Experimental results from bistatic hitchhiking radar are shown for the purpose of aircraft detection. The data presented has been processed non-coherently. For suppression of device noise and scan-to-scan stationary clutter a signal analysis method called "target back propagation technique" has been used. Sampled radar data containing 6 aircrafts is presented. The technique is used on an image with bistatic geometry averaged over 3 scans and with target back propagation locally applied for each aircraft. All aircrafts are sharpened in the image and this illustrates the usefulness of the "target back propagation technique" for suppression of device noise and stationary clutter, even if just three scans are integrated.