What is an antenna alternative?

Answer 1

By definition an antenna (aerial) is a piece of conductive material which receives (or radiates) radio waves. So there is no alternative to it if the signal is airborne and transmitted by radio signal.

However, TV pictures can be transmitted using other methods which although using radio waves (light is a radio wave remember) doesn't use an aerial in the strict sense of the word. TV information can be transmitted as a captured signal in coaxial or open feeder cable like cable TV. This is still a radio signal being used but its not (supposed) to be radiating (although it does leak if badly installed).

More recently fibre optic cables have replaced traditional copper wires to carry the information. This uses a modulated laser on multiple frequencies to transmit information to a converter which then produces voltage signals that a TV can decypher and produce an image from.