Additively-manufactured multilayer dielectric radome for enhanced scanning performance of a Vivaldi array antenna

Sammanfattning

This thesis presents the design and analysis of a multilayer dielectric lens aimed at enhancing the scanning performance of a fully metallic, dual-polarized Vivaldi array antenna. The radome introduces lensing capabilities that mitigate scan losses and improve gain flatness up to ±60◦ scan angles. Both antenna and radomes are meant to be additively manufactured. Array antennas are widely used in wireless communications, radar detection, and satellite systems, where the ability to form and steer highly directive beams is their main attractive. In particular phased array antennas enable electronic scanning by applying progressive phase shifts between elements, thus avoiding mechanical movement. However, when using planar phased arrays, the antenna experiences reduced gain when scanning at large angles also known as scanning losses. This drawback motivates the integration of lens-based radomes as a mean to extend the scanning range. The design process combines the use of a fast ray-tracing physical-optics model developed at KTH with full-wave validation using CST Studio Suite. A two-layer radome configuration was optimized, and the influence of additional matching layers was investigated to minimize reflection losses. Manufacturing feasibility was assessed through the characterization of ABS300 material using a body-centered cubic metamaterial unit cell to achieve the required effective refractive indices in the different layers of the lens. Results demonstrate that the proposed radome can equalize the gain across wide scanning angles, mitigating pointing degradation at extreme angles. Although certain limitations appeared at higher frequencies, the work affirms the potential of lens-based radomes in improving the scanning capabilities of array antennas.