A lens-based antenna with a solid dielectric ellipsoid PTFE lens for industrial tank level probing radar (TLPR) is presented. Due to limitations of the application, a high antenna gain at a limited size as well as a good matching were the main design goals. The presented antenna achieves a high gain of 25.9dBi with a beamwidth of ≈ 8.4° at an outer diameter of 74 mm in simulations, which is confirmed by measurements. Despite the lens surface reflections, a good input matching of ≈ -20 dB is achieved in the full wide frequency band from 23 GHz to 28 GHz, which enables monostatic radar operation even close to the antenna. A laboratory radar setup is used to confirm the accuracy impact on distance measurements in a scenario with disturbing reflectors.