Do receiving EMF antennas send out EM radiation? EM waves cause the electrons in the metal of a receiving antenna to oscillate at the same frequency of the wave.
So in the receiving antenna, there are 'currents / accelerating charges' moving back and forth.
Accelerating charges cause EM waves.
Does this mean that a receiving antenna sends out the same waves again after receiving them?
 A: A certain amount of the radiation that strikes a radio antenna will bounce off it and of this, a tiny amount will be returned to the transmitter from which the signal originated. 
The reflected signal generated by a receiving antenna is minimized by impedance-matching the electrical characteristics of the antenna for the specific frequency of the incoming radiation. This condition also maximizes the amount of electrical power that the antenna sends to its receiver. 
A: Yes.  Any type of conductive material will absorb voltage or EMF and emit it. This includes radio, tv, mobile phone, wiFi, hair drivers, appliances, electrical lines, ECT.
Any electrical wire, even unplugged, will absorb and emit EMF, its similar to a passive antenna having a "gain dB" level. The problem is that repeated grounding is needed to remove this EMF in passive wiring which functions similar to direct current (D/C). Active wiring, with a flow of alternating current (A/C), should have a hot/neutral in close proximity to cancel out the emitting EMF. Unless you live in a house surrounded by steel walls which penetrate 4ft into the ground, it won't be easy to remove the D/C EMF emitted by various wireless technologies.
So yea, even if your Christmas tree is unplugged, the wires are still absorbing and emitting a EMF. Get a high quality EMF meter which is able to detect 5hz-3.5Ghz range if you don't believe me.
