A Low Complexity Multi-Mode Radio Vortex Receiver for OFDM-OAM Networks

Using the array signal reception theory, we analyzed the mathematical model of the proposed time-modulated rectangle array (TMRA). For practical applications, the uniform circular arrays (UCAs) used in orbital angular momentum (OAM) based multiple-input-multiple-output (MIMO) systems are replaced by the general uniform rectangle arrays (URAs). The employment of radio frequency (RF) switches at the bandlimited receiver significantly reduce the hardware overhead and avoid the unlimited spectrum expansion caused by switches. The detailed derivation of an example of 4 × 4 TMRA time-modulated sequence (TMS) is given in this letter. Our numerical results demonstrate that the TMRA receiver obtains better reception gain, bandwidth, and sidelobe control than a single UCA based OAM receiver.