[MatrixDweller]

Computer networks suffer from the same problem. HDMI is a digital signal too so it's not a far stretch to see what's going on. CAT5e (100MHz) and CAT6(250MHz) become unreliable after 90-100 meters. Repeaters are required at or before that distance to ensure reliability.

CAT5e uses 24AWG copper primarily and CAT6 uses 22 or 24AWG copper. HDMI 1.0 is up to 165MHz or 4.95Gbits (1080p60) and HDMI 1.3 is up to 340MHz or 10.9Gbits (1080p60@48bits). Try to pass that signal over 28AWG copper and it's not going to make it 25 feet. Bump up the AWG of the wire and you'll reduce the attenuation so 24AWG will give the signal a longer run and 22AWG even longer. Attenuation increases when the transmission frequency increases though too. 1080i/30 or 1080p24 signals are not as much of a problem since they have a lot less bandwidth than 1080p60.

So HDMI 1.3 cables will either need to be fire hose sized, or have some other way of mitigating the attenuation to stretch the distance. That's where repeaters or signal regenerators come in.