|Where does the charge on the antenna come from?
In the transmitting station, the moving charge is pumped back and forth between the ground and the antenna. The net charge in the vicinity of the station remains zero, but it is constantly being redistributed. Sometimes the antenna is positively charged and the ground is negatively charged and sometimes it's the reverse. In the receiving station, the same may be true. But there are also hand-held receivers that do not touch the ground. In that case, the receiver is still neutral, but charge is being pushed back and forth along the antenna and tank so that when the antenna is positively charged, the bottom of the tank circuit itself is negatively charged.