Design and Analysis of UHF Passive Dipole Antennas for Moisture Detection using RFID technology

RFID technology is taking over the market of sensor applications in the medical and healthcare industry. Radio frequency identification (RFID) tags are cost-effective and have better performance than other sensor applications. In this paper, we propose UHF passive antennas for moisture detection which can be used in the medical and healthcare industries. Dipole antennas working in UHF which has omnidirectional radiation patterns are designed and fabricated using RFID chip NXP UCODE G2iL SOT886 in the SMILE research lab which is tested in a different environments for the detection of moisture. Based on the antenna parameters the dry state and wet state of the environment is differentiated. The performance and results of dipole antennas like a meander dipole antenna, folded dipole antenna with closed loop and T-matched dipole antennas are compared and discussed in this paper. The dipole antennas are designed using HFSS simulation software at 866 MHz to achieve the antenna impedance of 25 + j237 ohms which is the complex conjugate of the load impedance. From the simulation and experimental results, it is found that the T-Matched dipole antenna has better antenna performance in terms of read range and detecting the moisture in the environment.