A Fast and High-Resolution Microwave Resonant Frequency Measurement Approach

The dataset includes the frequency-sweep ranges predicted by a physical model, the measured complex transmission parameters (S₂₁), and the resonant parameters extracted using optimized algorithms.The dataset was constructed and validated using a Single-Pressure Refractive-Index Gas Thermometry (SPRIGT) experimental platform, which integrates gas handling, cryogenic temperature control, microwave measurement, and data acquisition systems.

The measurement procedure first predicts the sweep interval containing the complete resonance triplet based on temperature and pressure using a physics-based model. A hybrid sweep method is then employed, allocating uniformly spaced frequency points to the background regions and uniformly spaced phase-angle points to the resonance region. Finally, the resonance frequency and half-width are precisely extracted from the measured complex S₂₁ data through a two-stage process: an optimized linear rational-function initialization followed by nonlinear Lorentzian fitting.This dataset comprehensively documents the frequency prediction errors, iterative convergence processes, frequency calculation uncertainties, and the application outcomes in RIGT temperature determination for various microwave modes (TM₁₁, TM₁₂, TM₁₃, TE₁₁, TE₁₂, TE₁₃) under vacuum and different pressures.