For example: Agilent E4440A or Anritsu 68369
Anritsu Power Sensor
Anritsu MA2442B
Power Sensor, High Accuracy Diode, 10 MHz to 18 GHz, -67 to +20 dBm
Manufacturer: Anritsu
Anritsu MA2444A
Power Sensor, High Accuracy Diode, 10 MHz to 40 GHz, -67 to +20 dBm
Manufacturer: Anritsu
Anritsu MA2445A
Power Sensor, High Accuracy Diode, 10 MHz to 50 GHz, -67 to +20 dBm
Manufacturer: Anritsu