Design of a Wideband THz 2-D Spatial Power Combiner Based on Mode Conversion Method

This article presents a wideband terahertz (THz) 2-D M x M spatial power combiner (SPC) based on a mode conversion method. It consists of a transmitting array, a transmitarray (TA), and a receiving antenna, which are integrated in a sealed metal cavity. The TA provides phase manipulation to transform the TE₁₀-mode M×M beams from the transmitting array to the Gaussian beam matched with the receiving antenna. The proposed SPC achieves efficient power combining in a wide bandwidth by designing the low-loss dielectric TA elements with a linear phase shift and a wideband transmitting/receiving antenna. A 3-D printed 4×4 THz SPC is designed and fabricated. The measured output and input return loss are greater than 12 and 9 dB, respectively, and the combining efficiency is 54%~74% within 230–325 GHz (34.2%). The proposed M×M THz SPC can be applied for THz high-power sources based on photodiodes. © 2025 IEEE.