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Radar imaging based on electromagnetic vortex can achieve azimuth resolution without relative motion. The present paper investigates this imaging technique with the use of a single receiving antenna through theoretical analysis and experimental results. Compared with the use of multiple receiving antennas, the echoes from a single receiver cannot be used directly for image reconstruction using Fourier method. The reason is revealed by using the point spread function. An additional phase is compensated for each mode before imaging process based on the array parameters and the elevation of the targets. A proof-of-concept imaging system based on a circular phased array is created, and imaging experiments of corner-reflector targets are performed in an anechoic chamber. The azimuthal image is reconstructed by the use of Fourier transform and spectral estimation methods. The azimuth resolution of the two methods is analyzed and compared through experimental data. The experimental results verify the principle of azimuth resolution and the proposed phase compensation method.

A modified uniform circular array is analysed and configured to generate radio waves carrying orbital angular momentum (OAM). The relationship between OAM mode and array parameters is derived mathematically. Results show that the produced OAM mode can be altered arbitrarily by changing the exciting frequency when the array is fixed. Moreover, the OAM mode is associated with elevation angle, offering the potential of elevation resolution for radar imaging.