For example: Agilent E4440A or Anritsu 68369
RF Power Measurement
Anritsu PSN50-ES310
High Accuracy Power Sensor, 50 MHz to 6 GHz, -30 to +20dBm

Manufacturer: Anritsu
Keysight / Agilent U2000B
10MHz to 18GHz USB sensor (-30 dBm to +44 dBm)

Manufacturer: Keysight / Agilent
Keysight / Agilent U2000H
10MHz to 18GHz USB sensor (-50 dBm to +30 dBm)

Manufacturer: Keysight / Agilent
Keysight / Agilent U2001B
10MHz to 6GHz USB sensor (-30 dBm to +44 dBm)

Manufacturer: Keysight / Agilent
Keysight / Agilent U2001H
10MHz to 6GHz USB sensor (-50 dBm to +30 dBm)

Manufacturer: Keysight / Agilent
Keysight / Agilent U2002A
Agilent U2002A 50 MHz - 24 GHz USB Sensor

Manufacturer: Keysight / Agilent
Keysight / Agilent U2021XA
Agilent U2021XA 50 MHz to 18 GHz USB Peak and Average Power Sensor

Manufacturer: Keysight / Agilent