Stability tests in time of OAM multiplexing schemes in highly disturbed environments
We report the results of tests of data transmission and signal stability in time of two different wide-band multiplexing (MUX) schemes, each in a point-to-point configuration, based on electromagnetic waves carrying Orbital Angular Momentum (OAM) in noisy real-world settings. Each radio link transmitted two high definition wide--band analog TV channels in the same frequency band with FM-carrier centered at $2.414$ GHz and $27$ MHz bandwidth, encoded with different OAM modes in the same polarization state, uninterruptedly for $5$ months during the world exhibition ``Globale--Digitale'' at ZKM in Karlsruhe and in other $2$ months time slots taken in the following $4$ years, $24$ hours per day. We show the practical feasibility of the use of stable OAM radio/TV links in the real world for a long time, paving the way for for secure and efficient communication schemes also under electromagnetic jamming conditions.