A Local Two-Port Interferometer to Detect Radio-vortices at 30 GHz

In this work we show a novel method based on a local two-port interferometer to distinguish the topological charge of radio-vortices at 30 GHz by using a small portion of the entire wavefront only. The experimental investigation of the amplitude and phase properties of the interference pattern with a pure Gaussian beam (l = 0) and a l = 1 radio vortex is carried out, and results are compared with the theory based on Laguerre-Gauss modes. Experiments were performed both with the interferometer and with single antenna to highlight the effective benefits of the interferometric approach, sensitive to the azimuthal phase of the vortex field. Method is also extendable at higher topological charges for applications to high-density millimetric communications.