For example: Agilent E4440A or Anritsu 68369

Signal Generators

RF and microwave signal generators, PXI and PCI signal generators include versatile arbitrary waveform generators, function generators, and RF vector signal generators.

Manufacturers: Keysight / Agilent, Rohde and Schwarz, Marconi, Anritsu, Keithley Instruments, Aeroflex IFR, Fluke, Tektronix, Gigatronics, National Instruments, Instek, Wavetek, IFR Systems