Nowadays radar systems play an important role in military and civil applications. Among various radar applications, radar imaging constitutes an important one. Imaging radars include both Synthetic Aperture Radar (SAR) and Inverse Synthetic Aperture Radar (ISAR). In the SAR, radar is usually carried by airplane or satellite, and generates images from cities, earth, etc. On the other hand, in the ISAR, radar is usually located in site, and generates images from moving targets such as missiles, airplanes, etc. Conventional ISAR systems use Fourier Transform to retrieve Doppler spectrum and image formation. But due to the complex motions of target, the Doppler spectrum is time-varying and hence the image formed by Fourier transform becomes blurred. In such cases, polar reformatting algorithm can be applied to compensate the effect of time-varying Doppler spectrum and prepare the results for the use of Fourier transform. Unfortunately, in situations where complex and maneuvering motions exist, polar reformatting performance is not acceptable. In the 90s, Joint Time-Frequency Transforms (JTFT) has been proposed to resolve the problems associated with Doppler spectrum and image formation. In this thesis, the linear and bilinear JTFT including Cohen ltr"
