A 3D-Printed Holographic Impedance Surface for Sub-THz Enabled by Transmission Line Method

The eigenmode method is typically leveraged to determine the dispersion characteristics of the element for holographic impedance surface (HIS), i.e., the relation between surface impedance and the element geometry of a HIS. This relation is based on curve fitting according to the extensive simulation samples, which is time-consuming due to the great number of simulations needed to ensure accuracy, especially at the high-frequency bands (e.g., sub-THz or THz). As the sub-THz and THz frequency spectra are promising for 6G wireless communications, an effective method is highly demanded to significantly reduce the holistic design period. To this end, the transmission line method is proposed to directly formulate the relation between the surface impedance and the element geometry, which highly reduces the design complexity and time. For proof of the concept, a 3D-printed HIS enabled by the proposed TL method is demonstrated. In addition, the traditional eigenmode method is also presented and compared with the proposed TL method to validate the effectiveness of the latter method. The performance of the proposed 3D-printed HIS has been verified with full-wave simulations.