Rotational Doppler effect based on the radio orbital angular momentum wave

The rotational Doppler effect based on the radio orbital angular momentum (OAM) carrying wave has been theoretically studied and experimentally verified at 10 GHz. By using the higher-order OAM mode L=2 and L=3 as the incident wave, the rotational Doppler frequency shift and the inevitable micro-Doppler frequency shift are successfully distinguished. Since the wave vector of radio OAM wave includes both the radial component and azimuthal component, which are related to linear Doppler frequency shift along the radial direction and rotational Doppler frequency shift, respectively, it has potential applications in 2D vector velocity detection.