Orbital-angular-momentum-based electromagnetic vortex imaging by least-squares method

Recently, the electromagnetic waves carrying orbital angular momentum are applied to radar imaging, which has the ability of azimuth resolution without motion limitation. The image reconstructed by Fourier transform method has low quality due to the high sidelobes and the duplicate of real target. In this paper, we reveal the reason in two cases with the help of point spread function. Then the least-squares (LS) method is adopted to get the high-quality imaging. The parameterized imaging model is detailed and several factors affecting the solution are discussed. Numerical experiments show that the results produced by using LS method are much nicer than that by Fourier technique when the noise and model error are not too serious. Moreover, the LS method can lower the limit of elevation angle. Finally, the imaging quality are analyzed quantitatively when the noise and model error are present.