HP-Agilent/Keysight 8485D

The 8485D diode power sensor measures average power over the frequency range 50 MHz to 26.5 GHz and power range -70 to -20 dBm (50 dB dynamic range).

Excellent SWR for reducing mismatch uncertainty
Accurate calibration and traceability to US National Institute of Standards and Technology (NIST)
Compatible with EPM (new N1913A/ 14A, E4418B/ 19B), EPM-P (E4416A/ 17A) and P-series (N1911A/ 12A) power meters, plus the E1416A VXI and discontinued 70100A and 43X power meter
Accurate average power measurements over -70 to -20 dBm
Frequency range 50 MHz to 26.5 GHz
Diode power sensing element
Datasheet