The closer in size your antenna comes to the size of the wavelength you want to listen to, the better your chances are of receiving it. If you took that same antenna, no core needed, and wired it into a telephone line, you will probably raise the signal on the baseband channel into the low end of the radio band. Modern radios don't use this principle to produce a high frequency carrier wave, of course, but the point I am making is that an induction coil to produce electromagnetic radio waves was an element which distinguished Hughe's work from more primitive schemes. None other than Alexander Graham Bell, the man who invented the telephone and of course made the first call on a wired telephone to Thomas Watson. Bell was also first with radio, although in a way you probably wouldn't imagine.
Inductive reactance is the proper term for opposition to current flow through a coil.
Resistance of a circuit and inductive reactance, both measured in Ohms, makes up impedance. In many radio discussions AC does not mean the alternating current that powers your appliances, rather, it means the way audio signals alternate in a wave like fashion. As we've just seen above and on the on the previous page , we need a change in current flow through a coil to get radiation. Current must go on and off to release the electromagnetic energy stored within the coil. AC in radio means the natural alternating current of a voice signal, that is, the normal up and down waveform of the analog signal.