Time-frequency-based millimeter ISAR image formation

In high range-resolution radar system, in order to achieve high range resolution, signals having wide bandwidth are required. The higher the working frequency is used, the more bandwidth is got. Stepped frequency waveforms in millimeter wave band is available to get one-dimension multiple scattering centers distribution or the profile, furthermore, two dimension multiple scattering centers distribution can also be got while the target is rotated according to the theory of ISAR processing. In order to get experimental data, A millimeter wave ISAR system is designed. The Range-Doppler algorithm and the time-frequency representations have been investigated. One of the time-frequency representations is Wigner-Ville distribution, which has a better energy concentration than the RD algorithm, but when multiple scatters are distributed in one range cell, the Range-Doppler algorithm can also recognize them but the WVD may be blurred. So there is a tradeoff in energy concentration and resolution.