The small black 'loop' connects to the transmitter / receiver. That picks up the signals received by the larger copper loop which is about 1 meter in diameter. Just above the copper loop is the tuning mechanism which has to be designed to handle high voltages. It might be low power being transmitted but in excess of 1000 volts can be generated at the top section. These aerials seem to need little power to send signals a fair old distance. I use just 10W which is one tenth of the full power of my transmitter and one fortieth of the power I am licenced to use. Best contact to date has been 4177 miles to a station in the US using a digital mode called FT8 on the 17m band.
With most aerials the higher up they are the better they work but the magnetic loop seems to work miracles when close to the ground.
