A passive RFID-based security detection sensor for doors and windows

This paper designs a passive chipless RFID door and window security detection sensor operating at a fundamental frequency of $f_{0}=915$ MHz. The dielectric substrate of the sensor is a 1.5 mm thick FR_4 double-sided copper-clad board, and the overall structure includes a fundamental frequency receiving antenna, a frequency doubling circuit, a second harmonic filter, a magnetic induction switch, a magnet and a harmonic transmitting antenna, which has the features of simple structure, long detection distance, low cost and high robustness. The experimental results show that the working distance between the reader and the sensor can reach more than 4 m when the transmitting power is 20 dBm under the condition that the door or window is opened accidentally, which can realize the long-distance monitoring function.