No abstract

Octafilar helical antenna (OFHA) is proposed for handheld ultra-high-frequency (UHF) radio frequency identification (RFID) reader. The investigated antenna configuration consists of OFHA placed on reader device in the presence of human hand model. The antenna is designed at UHF band centered at 915 MHz. The antenna return loss, axial ratio, gain, co-polarized and crosspolarized field components are calculated using the finite element method (FEM) and compared with that calculated by finite integration technique (FIT) for verification of the simulated results. A comparison between the performance of the quadrifilar helical antenna (QFHA) and the octafiliar helical antenna (OFHA) designed at 915 MHz in the presence of the reader device and human hand model is investigated. The OFHA introduces high gain, high front to back ratio, good axial ratio and omnidirectional coverage.

Electrosurgical generators (ESGs) are currently the most widely used surgical technology for clinical operations. The main disadvantage of ESGs is their output power is irregular due to the variable tissue impedance. The heat dissipation caused by the high amount of thermal energy generated leads to medical complications for both patient and surgeon. In this research, various inverter topologies and power controllers are investigated to specify the best structure that ensures best performance. The type of inverter topologies investigated are three level and five level, while the PID structures investigated are integer order (IO-PID) and fractional order (FO-PID). The simulation results indicate that FO-PID with five level inverters is better than IO-PID with three level inverters in terms of minimum heat dissipation rate and THD of the output voltage and current.