Its been a while since I studied physics, so pardon my ignorance. I have two near field antennas (NFC). The range of the antennas is about 2-3 cm. I am looking for a way where I can block and unblock the communication between them. One of the way that I tried is to place a flat tightly woven wire (shown below) between the two antennas like a sandwich. If I short the two ends of the wire, I was able to block the communication. My assumption is that it is effectively reflecting the signal and thus blocking the signal. Is that what is happening? If I un-short the two ends, then, two antennas are able to communicate without any issue. However, if the radio signal has good strength, the coil is not doing a good job. Is there any other better solution that I can effectively block/unblock. I could just put a sheet of metal in between but I chose the wire solution so that I can block/unblock using a relay controlled via electronics. Can someone suggest a better solution ?