For example: Agilent E4440A or Anritsu 68369
Keysight / Agilent Signal Source
Keysight / Agilent 3245A-001
Agilent 3245A-001 Universal Source with Option 001 Second Channel Output

Manufacturer: Keysight / Agilent
Keysight / Agilent 83554A
Millimeter-Wave Source Module, 26.5 GHz to 40 GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent 83555A
Millimeter-Wave Source Module, 33 GHz to 50 GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent 83557A
Millimeter-Wave Source Module, 50 GHz to 75 GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent 83599A
RF Plug-in for the Keysight 8350B, 10 MHz to 50 GHz

Manufacturer: Keysight / Agilent
Keysight / Agilent B2901A
Precision Source/Measure Unit, 1 ch, 100 fA, 210 V, 3 A DC/10.5 A

Manufacturer: Keysight / Agilent