Over-the-Air Noise Figure Measurement of 110–170-GHz Active Integrated Antennas Using Photonic Noise Source

Significant path loss at terahertz frequencies and the variation of antenna gain with distance pose key challenges for over-the-air (OTA) noise figure (NF) measurement of terahertz active integrated antennas (AIAs). This paper proposes a differential Y-factor OTA NF measurement method using a tunable photonic terahertz noise source with high excess noise ratio (ENR). The method eliminates the need for ENR calibration and ensures sufficient excitation power for OTA measurements under high-loss conditions. To further enhance accuracy, a dynamic gain calibration technique is introduced to address distance-related gain variation, enabling consistent NF measurements in both near-field and far-field scenarios. The effectiveness of the proposed approach is validated through measurements on a D-band (110–170 GHz) AIA. The NF measurement results show strong agreement with conducted reference values and consistent performance across different measurement distances.