Chirp Signal Transmission and Reception With Orbital Angular Momentum Multiplexing

Vortex electromagnetic waves, which carry the orbital angular momentum (OAM), can increase channel capacity by utilizing OAM multiplexing technology in optical field. In order to fully exploit OAM mode-division multiplexing in radio domain, a crosstalk matrix of the communication channel between the multi-OAM-mode transmission and reception is deduced theoretically in this letter. The crosstalk matrix shows that it is achievable to communicate between the same OAM modes but not possible between different OAM modes. To confirm this statement, a near-field proof-of-concept communication experiment, transmitting and receiving linear frequency modulation signals with different frequency modulation (FM) rate using uniform circular array antenna, is then carried out. The experimental results show that the crosstalk between different modes meets the requirements of near-field communication. It may also be beneficial for the application of the vortex wave for radar imaging in the future.