For example: Agilent E4440A or Anritsu 68369
Gigatronics
Gigatronics 80340A
POWER SENSOR 50MHZ TO 18GHZ , TRIGGERABLE , PEAK OR AVERAGE , ALSO WAVETEK

Category: AC Line Analyzers
Gigatronics 80401A
Gifatronix 80401A Power Sensor, 0.01 GHz - 18GHz, +20dBm to -67dBm, FM <40KHz

Category: RF Power Measurement
Gigatronics 8652A
Gigatronics 8652A Dual Channel Universal Power Meter, 40 GHz w/ Option 12

Category: RF Power Measurement
Gigatronics 8652A-12
Gigatronics 8652A Dual Channel Universal Power Meter, 40 GHz w/ Option 12

Category: RF Power Measurement