Hello,
Do you have any data about the HMC773ALC3B behaviour working as upconverter with the following frequencies?
IF= 4.5Ghz
LO= 9.5Ghz to 10.5 GHz
RF= 5Ghz to 6GHz (LOWER SIDEBAND)
Even if according to the data sheet, min RF is 6Ghz, there is no rolloff on the conversion loss at 6 GHz so it looks like the mixer could work below this frequency.