While some of the spectrum held by the military would be useful, most of it wouldn't be, same goes for whats currently used for police too. The issue with lower frequency spectrum (say, sub 550 mhz) is it starts to interact with the atmosphere and can result in some off propagation patterns (like tropospheric ducting).
I also suspect that the users of that spectrum (save for the military which has a huge amount of lightly used spectrum) might disagree with you as to how useless their technology is, I mean would you take the spectrum currently held for ham radio operators and sell it off?
Navigation (GPS) is pretty spectrum efficient, so I'm not really sure what you're getting at there.
I think theres plenty of useful spectrum to go around between 2.4GHz and 5.8
All the legacy nonsense needs to be ruthlessly eliminated. People claim frequency auctions are efficient but that's clearly not the case if you are only auctioning .1% of whats useful and allocate the remainder to waste on a free cost basis.
I think perhaps for home broadband (read wifi) use sure, we could free up another 200 mhz easy - as replacement for mobile broadband.. you wanna look between 600-1900 mhz there, anything much above 2.5 is too high (read expensive) to build a mobile network with because of site spacing.
Much of what's in that band is allocated for point to point microwave and satellite, I'd also caution you, one mans 'wasted spectrum' is another 'vital important service' both of which can be technically correct at the same time.
I also suspect that the users of that spectrum (save for the military which has a huge amount of lightly used spectrum) might disagree with you as to how useless their technology is, I mean would you take the spectrum currently held for ham radio operators and sell it off?
Navigation (GPS) is pretty spectrum efficient, so I'm not really sure what you're getting at there.