UMass is aboslute strong in this field. Pozar, Schaubert, Jackson and Yngvesson are gurus in antenna, wicrowave and RFIC research. Check out the research fellows in Infineon and RFMD. Lots of them are UMass Alumni.
I don't think there is one univ in general -
each one is good in different areas of research in mw eng.
Umich is also pretty good - and Georgia Tech has many areas of research!
my 2 points...
For graduate school, tutition will cost you about 22,000+ a year if you go to any of the schools mentioned on this board unless you can obtain a fellowship. In addition, living expenses (rent, food, books, etc...) will cost you around 700~1000 a month depending on where you live in the US.