How do I select a power meter and sensor for accurate measurements at millimeter wave frequencies?

How do I select a power meter and sensor for accurate measurements at millimeter wave frequencies? Accurate power measurement at mmWave (above 26 GHz) requires sensors specifically designed for these frequencies, with attention to connector type, frequency response flatness, and calibration traceability: (1) Power sensor types for mmWave: thermocouple sensors: frequency range: DC to 50-110 GHz. Power range: -30 to +20 dBm. Accuracy: ±0.02-0.05 dB (highest accuracy at mmWave). Response: slow (100 ms-5 seconds). Best for: calibration and reference measurements. Examples: Keysight 8487D (50 GHz, 2.4 mm), Keysight W8486A (75-110 GHz, waveguide WR-10). Diode sensors: frequency: 10 MHz to 50-67 GHz. Power range: -70 to +20 dBm (wide dynamic range). Accuracy: ±0.1-0.2 dB at mmWave (frequency response becomes less flat). Response: fast (< 10 ms). Examples: Keysight U2004A (50 GHz, 2.4 mm), R&S NRP-Z58 (40 GHz). Peak/Modulated sensors: needed for 5G FR2 TDD signals (pulsed, time-gated measurements). Must capture the peak envelope and average power independently. Examples: Keysight N1924A with N8487A sensor (50 GHz, 2.4 mm, peak + average). (2) Connector considerations: 2.4 mm connector: rated to 50 GHz. The standard connector for mmWave power sensors below 50 GHz. 1.85 mm connector: rated to 67 GHz. Used for V-band power measurements. 1.0 mm connector: rated to 110 GHz. Required for W-band measurements. Waveguide flanges: WR-15 (50-75 GHz), WR-10 (75-110 GHz). Required for above 67-70 GHz. Each connector requires mating cables and adapters of matching type. Cross-type adapters (e.g., 2.4 mm to 1.85 mm) must be high quality to avoid reflections and measurement error. (3) Accuracy at mmWave: the dominant error sources at mmWave are: frequency response flatness: the sensor response varies more with frequency at mmWave (±0.5-1.5 dB without correction). Calibration factors (CF): frequency-dependent correction factors provided by the sensor manufacturer reduce this to ±0.1-0.3 dB. Mismatch uncertainty: at mmWave, the SWR of both the source and sensor is typically higher (1.3-1.8:1 vs 1.1:1 at lower frequencies). Mismatch uncertainty: ±0.2-0.8 dB at mmWave (dominant error source). Connector repeatability: each connection at mmWave introduces ±0.02-0.05 dB of uncertainty. Minimize the number of connections and adapters. (4) Cost: mmWave thermocouple sensor (50 GHz): $3,000-6,000. mmWave waveguide sensor (110 GHz): $8,000-15,000. Power meter (2-channel): $5,000-12,000. USB power sensor (eliminates separate meter): $3,000-8,000.