Hi there,
What are you trying to accomplish? That impacts how it should be set up.
Also what sort of signals are you trying to generate? There's a big difference between HF (low MHz) and microwave (GHz+) sources, and there's a big difference between a pure tone at one frequency, a tone you can sweep across frequencies, and a broadband noise source. But all of them are microwaves, and all can produce at low and constant power.