Generating Steering Orbital Angular Momentum Vortex Beams Using Conical Conformal Array Antenna

In this letter, we propose using the conical conformal array antenna to launch the steering electromagnetic orbital angular momentum (OAM) vortex waves. First, the theoretical calculation method for generating the steering OAM beams using conical array antenna is deduced and the formula of compensated phase shift for each antenna unit located in the conical array is derived. In addition, a polarization correction approach is proposed to achieve better radiation characteristics of the OAM vortex beam. Next, a prototype of a conical conformal array antenna, which consists of 114 U-slot microstrip patch antennas, is fabricated and experimentally verified. The measured results indicate that using the conical array antenna to launch steering OAM vortex beams directed at the elevation angle of 0 degrees to 60 degrees can prevent significant distortion and guarantee high mode purity even though the scanning angle becomes large. This could serve as a reference for potential future applications of electromagnetic vortex communication on a conformal carrier.