Imaging and Motion Parameter Estimation of Flying Helicopter With Duo Airborne SARs in $X$-Band

Duo airborne synthetic aperture radars in the
$X$
-band are proposed to acquire images of a flying helicopter. The backscattered signals manifest entangled features attributed to the compound linear motion of fuselage and spin motion of rotors. A two-stage template matching method is proposed to meticulously untangle signals from moving fuselage and spinning main rotors and tail rotor. The velocity vector of fuselage and the spinning rate of main rotors can be accurately estimated, and the spinning rate of the tail rotor can be estimated after removing the strong signals from fuselage and main rotors. The acquired images in different scenarios are evaluated and verified with three state-of-the-art algorithms.