Radio channel multiplexing with superpositions of opposite-sign OAM modes

Exploiting orbital angular momentum (OAM) to implement spatially multiplexed links is an active research topic, both at radio and optical frequencies. We focus on using, in the microwave range, superpositions of modes having opposite OAM values. As known, this approach simplifies dramatically the spatial field distributions, especially in phase. We stress the consequent implementation advantages, and test them experimentally, on an ad-hoc link, about 100 m long, at the unlicensed frequency of 17.2 GHz, in an urban environment. Results are compared with numerical simulations. Performances are discussed vs. those of a conventional MIMO system.