Sat Mar 26, 2016 11:44 pm
Nope... not for gigabit.
Gigabit uses all 4 ethernet wire pairs, so to carry DC power along with AC signal on wires 4,5 and 7,8 you need a phantom powering scheme to be able to inject DC at one end, and "extract" it at the other, which is what that whitepaper depicts for PoE af/at.
Phantom powering is something that has been done for ages to power active microphones.
However, why would you need transformers? To power PoE-in gigabit capable routerboards (most) nothing else than stock poe injector (RBGPOE) or PoE-out port at the other end, by the HEX PoE and a ethernet cable is needed, no need for transformers, they're built in.