Litz wire is made of individual strands that are coated with an enamel or plastic to insulate them. Ordinary wire has no strand coating and so they are in electrical contact with each other. Since electricity travels in the outer skin of the strands, Litz wire has a lower resistance compared with an equivalent wire without the coating since there is more surface area available to conduct electricity.
Litz wire costs more than regular wire and the strand insulation must be removed from the ends to make electrical contact, usually by dipping the ends in a solder pot.
Some types of Litz wire is woven in a way to minimize magnetic field emissions, which will not work well as antenna wire.
A lower resistance can be obtained by using a larger diameter regular wire, which costs less and is easier to work with.