Yes, you can mulitply and I do that as well. But this a part of the measurement techniques and not really part of the discussion at hand. Besides, the multiplication scheme adds noise and you must calibrate that to be accurate. If they do not have a means of phaselocking and comparing two relatively equal oscillators at its fundamental frequency, then it does not matter how many times they multiply it. Using a millimeter wave spectrum analyzer does not really change this inaccuracy as the noise floor of the spectrum analyzer goes up with each range multiplication so it does not allow you to measure a 10811 even at 40GHz. You can't get "something for nothing". You can definitely benefit from the multiplication ONLY if you know exactly what the multiplier contribution is and then use a phase detector at the mm-wave frequency and thus are getting back to DC/baseband and not reading this on an RF spectrum analyzer.
I do not know whether your time spent measuring the phase noise of mm-wave sources was for ham radio or for work. If it is for a very important work project, then ask them to invest in the Poseidon (spelling?) oscillators from Australia. They are using machined sapphire cavities suspended in liquid helium as the resonant structures. These are in the 10-12 GHz range so you would need to then multiply them up. There are lots of papers in the IEEE UFFC Transactions. 73, Jeffrey Pawlan _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
