An approach to forward looking FMCW radar imaging based on two-dimensional Chirp-Z transform

Airborne forward looking radar imaging, which is an important work mode of imaging radar system, has many advantages combined with frequency modulated continuous wave (FMCW) technology. This paper studies the configuration with one central antenna element for signal transmitting and other antenna elements for signal receiving. According to its imaging geometry, the analytical expression of the received signal for forward looking imaging radar based on FMCW is given. By performing the equivalent phase center principle, the received signal is equalized to the case of system configuration with antenna both for transmitting and receiving signals. The Doppler frequency shift effect, induced by the platform’s continuous motion while radar transmits and receives signals, is analyzed in detail and the approximate compensation method is shown. Based on this, a novel method for forward looking FMCW radar imaging is developed, which adopts two-dimensional Chirp-Z transform to implement scaling operation. Also the complete derivation process of the algorithm and the expression of each compensation factor are presented. The whole algorithm only includes FFT and complex multiplication, with interpolation free, and is easy to implement in reality. Simulation results verify the correctness of the analysis and the validity of the proposed algorithm.

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