High-accuracy measurement of Ku-band microwave antenna gain with Rydberg atom quantum sensing

Antenna gain reflects the ability to concentrate input power and radiate electromagnetic waves in a specific direction, and is a key indicator for evaluating antenna performance. In this paper, a high-accuracy Rydberg-atom-assisted gain-transfer measurement method is proposed for Ku -band microwave antenna gain calibration. The microwave electric field (E-field) intensity is precisely measured via electromagnetically induced transparency (EIT) and Autler-Townes (AT) splitting effects. Under the same experimental conditions, the microwave intensity distributions of a standard gain antenna (SGA) and the antenna under test (AUT) are systematically compared, enabling gain calibration of the AUT at 12.007 GHz through the proposed method. Furthermore, a Rydberg atom microwave sensor with multi-level transitions ( \(nD5/2\) - \((n+1)P3/2\) , n =50 \(~\) 55), is employed to extend the calibration over a wide frequency range within 12.694 \(~\) 17.041 GHz, achieving a measurement uncertainty below 0.38 dB. This work establishes a systematic framework for microwave device calibration, providing both theoretical support and experimental validation for precision metrology of high-performance microwave components.