I guess it could be a bit of CAT5e, a fiber pair, TV transmitter, some random scrap wire and a couple of paperclips*...
AFAIK, digital signals for anything decently quick get modulated onto a carrier wave and at the other end a demodulator gets your bits out. Does 100baseT count as hight bandwidth these days? Even bandwidth is an analog term. Don't quote me on this - layer 1 stuff is an SEP. If the blinkenlights are a'blinkin that's all I care about at that level.
* Proven to work with serial links into network management port, not sure if you'll get a reliable 10Mbit through it.
Biting the hand that feeds IT
