Effect of Different Sizes of Parasitic Coil Placed on Table-Type 13.56 MHz RFID Reader/Writer on Communication Performance

13.56 MHz RFID system is a short-range wireless communication technology using magnetic fields. The communication performance of 13.56 MHz RFID system is easily affected by the surrounding environment because the intensity of magnetic field used for communication is kept low due to the Radio Law. To solve this problem, we are investigating a method to improve the communication performance of the system by adding parasitic elements. In this paper, we evaluate the effect of a parasitic coil on communication between a table-type 13.56 MHz RFID reader/writer and a tag placed on it. For the experiment, parasitic coils of different sizes were prepared, and the effect of different sizes of the parasitic coil on communication performance was evaluated.