Wideband Millimeter-Wave Dual-Mode Dual Circularly Polarized OAM Antenna Using Sequentially Rotated Feeding Technique

In this letter, a 2 × 2 wideband bidirectional dual circularly polarized (CP) orbital angular momentum (OAM) antenna array at millimeter-wave frequency is presented, which can be used to generate dual mode simultaneously by the sequential rotation feeding method. The proposed antenna array is composed of four bidirectional radiating dual CP elements that rotate 90° sequentially to each other in the clockwise direction. The antenna element structure consists of two metasurface patch layers that are loaded on the bidirectional cavity-back slot antenna based on substrate integrated waveguide technology. Results indicate that the left-hand circular polarization (LHCP) with a mode lOAM = -1 in the +z-direction and right-hand circular polarization (RHCP) with a mode lOAM = +1 in the -z-direction, over a wide impedance (S11 <; 10 dB) and 3 dB axial-ratio relative bandwidth of 32.3% from 26 to 36 GHz. An acceptable agreement has been achieved with the comparison between the measurement and simulation results. The proposed antenna provides a method of generating multimode OAM beams for wideband millimeter-wave wireless communication applications.