Fresnel based frequency domain adaptive beamforming for large aperture distributed array radar

Distributed array radar is a significant radar system, which can not only improve radar detection capability and measurement accuracy, but also suppress mainlobe interference effectively. However, due to its equivalent large aperture, the plane wave assumption fails. What's worse, target signals arriving at each array may have the envelope migration problem, thus the traditional adaptive beamforming method becomes invalid. This paper proposes a Fresnel based frequency domain adaptive beamforming method for large aperture distributed array radar. Instead of plane wave model, it uses the Fresnel model based steering vector to improve accuracy. Meanwhile, it transforms the time domain signal to frequency domain, and using the traditional adaptive beamforming method for each frequency point respectively. Finally, it accomplishes the frequency domain adaptive beamforming by an inverse Fourier transform (IFFT). In result, this method could eliminate the envelope migration problem effectively. Simulations illustrate the effectiveness of the proposed method.