3D-Printed Subterahertz High-Scanning-Rate Leaky-Wave Antenna Based on Metallic Spoof Surface Plasmon Polaritons

This letter proposes a 3D-printed sub-terahertz (sub-THz) fully metallic frequency-scanning (FS) periodic leaky-wave antenna (LWA) based on a spoof surface plasmon polaritons (SSPPs) transmission line. Glide symmetry is introduced into the conventional domino-type SSPPs transmission line to increase dispersion, thereby enabling a higher scanning rate. An asymmetric periodic modulation structure is designed to excite leaky-wave radiation while suppressing the open stopband (OSB) effect without extra elements. A gap waveguide (GWG) is utilized as the feeding structure, which mitigates energy leakage from potential assembly gaps and significantly reduces fabrication difficulty and assembly complexity. The SSPPs and GWG structures are monolithically fabricated using high-precision 3D printing and surface-metallized via magnetron sputtering of gold. Experimental measurements of a prototype demonstrate continuous beam scanning from -29° to +49° within the frequency range from 180 to 220 GHz, achieving a scanning rate of 3.9°/%BW. The peak gain varies between 11.13 dBi and 16.53 dBi. This work provides a cost-effective, high-performance and feasible solution for metallic FS LWAs, with promising applications in terahertz imaging and radar systems.