This is amazing.

I understand that while you can add substantial capacitance and inductance to make an "electrically long" short antenna for a long wavelength, its effectiveness at transmitting and receiving is still proportional to its size - the signal will be pretty weak?

Then I remembered the way these electrically short antennas work is by resonating the signal within themselves so you're basically transmitting a really high amount of power with a really low efficiency (and the rest stays confined between the antenna and its extra L/C loads until it gets transmitted).