Jeremy Horwitz / VentureBeat: FCC says it netted $4.47B for 5G mmWave bands in its spectrum auction and $2.7B for 24GHz and 28GHz bands with AT&T, T-Mobile, and Verizon as top bidders  —  Once touted as the key building block of 5G networks, high band millimeter wave spectrum has taken a back seat to longer-distance low …