Abstract Over-the-air antenna performance evaluation in the millimeter-wave band often relies on compact antenna test range systems, which require large reflectors and a substantial measurement range volume. Such setups are impractical for rapid testing in space-constrained environments such as antenna fault diagnosis in smartphone manufacturing facilities. This paper presents a novel design methodology for highly compact antenna inspection testing range utilizing offset parabolic reflectors specifically designed for 5G smartphones. The proposed design system employs three small offset parabolic reflectors configured to account for beam tilting caused by smartphone back covers, eliminating the need to physically reposition the smartphone during testing. By directing electromagnetic fields toward a fixed receiver antenna from multiple angles corresponding to different antenna module positions, the system streamlines the test procedure, significantly reducing measurement time and measurement range volume. The proposed antenna inspection testing range provides a cost-effective and efficient solution for 5G antenna fault diagnosis in manufacturing facilities, ensuring rapid and reliable inspection while minimizing space requirements on the production line.