3D-printed mm-wave dielectric spherical conformal transmitarray for multi-order and multi-beam OAM generation

In this paper, what we believe to be a novel 3D-printed mm-wave dielectric spherical conformal transmitarray with octagonal cylindrical dielectric elements is proposed for generating multi-order OAM beams. By adjusting the wall thickness of the cylindrical dielectric unit, a full 360° transmission phase shift with high transmission efficiency is achieved in the millimeter-wave band of 25-27 GHz. According to the design principles of spherical structures, the elements are arranged to form an OAM-generating spherical conformal transmitarray. By adopting the phase compensation principles, two transmitarrays with the array size of 7<i>λ</i> × 7<i>λ</i> (<i>λ</i> is the wavelength at 26 GHz) are designed and fabricated to generate first-order and second-order OAM beams, respectively. Additionally, a 9<i>λ</i> × 9<i>λ</i> transmitarray is designed to generate the first-order dual-beam OAM waves. The experimental results show good agreement with simulations, demonstrating that this approach not only reduces production costs but also enhances the application of 3D printing in conformal designs for communication and radar systems.