Design, Modeling, and Characterization of a Cascaded-Lens Antenna for 220–330 GHz With 51.1 dBi Gain

This paper presents a novel sub-THz high-gain cascaded-lens antenna design approach that employs Gaussian beam propagation combined with low-cost dielectric materials and standard manufacturing techniques. The proposed lens antenna, solely designed based on a Gaussian beam model, achieves a maximum measured peak gain of 51.1 dBi across a broad sub-THz frequency range from 220 to 330GHz, demonstrated for the first time, to the best of the authors’ knowledge. The antenna comprises a WR3.4 diagonal horn as the primary radiator and a cascaded pair of dielectric lenses, comprising a double-concave lens followed by a double-convex lens. This cascaded configuration effectively controls beam divergence, increases the effective aperture, and enables higher gain with a more compact horn-to-lens spacing than conventional single-lens designs. An analytical model based on Gaussian-beam propagation is developed to predict the antenna’s radiation characteristics, thereby reducing the need for time- and memory-intensive full-wave electromagnetic simulations in e.g., CST Microwave Studio Suite. The model’s accuracy is validated through comparison with both simulations and measurements for a single-lens configuration at 240 GHz, 280 GHz, and 320 GHz. The predicted results show excellent agreement with the measured radiation patterns and realized gain. For the cascaded-lens antenna, the theoretical and experimental peak-gain values agree closely across the entire operating band from 220 to 330 GHz. The proposed cascaded-lens antenna features a compact form factor, a high gain-to-aperture ratio of 13.01mm−2, a low sidelobe level of −40 dBc, and an aperture efficiency of 66%. These results highlight the cascaded-lens approach as an efficient and scalable solution for next-generation sub-THz high-gain antenna systems.