Radio frequency energy harvesting (RFEH) circuits can convert the power of communication signals from radio frequencies (RF) in the environment into direct current and voltage (DC power). In this study, the Greinacher full‐wave rectifier circuit topology was combined with a 180° hybrid ring (rat‐race) coupler which was a passive RF/microwave circuit. Thus, higher RF‐DC conversion efficiency was obtained. First, using the Greinacher rectifier topology, RFEH circuit operating at the center frequency of 1850 MHz was designed. Then, at this frequency, designing of the rat‐race coupler having 1000 MHz bandwidth was made. The S‐parameter measurements and simulation data of the designed coupler circuit were compared. Finally, the high efficiency rectifier circuit where these two circuits were used together was designed. The proposed rectifier circuit was constructed on 70 × 70 × 1.6 mm³ FR4 substrate material with a permittivity of 4.3 (ε_r = 4.3). The power conversion efficiency (PCE) of the rectifier circuit, which had 125 MHz bandwidth at the center frequency of 1850 MHz and was developed with rat‐race coupler, was calculated as 71% at 4.7 dBm input power. In addition, with this study, at −15 dBm input power, which was a relatively low power level, 40% PCE value was obtained.

As the wireless communications have recently expanded, the potential effects on human body of electromagnetic (EM) fields produced by the base-station antennas has become of great concern to people especially living near the exclusion zone of the antennas. This letter presents the simulation of an electromagnetic radiation exposure and the calculation of specific absorption rate (SAR) and temperature variation for a multilayer human tissue model. The fact that field equations for planar wave propagation are analog to the circuit equations for a wave on a transmission line is exploited to use the lossy transmission line models of the ORCAD PSpice simulator. Exposure simulations are carried out considering a distance of 10 m between a base-station antenna and a multilayer human tissue model for exemplary frequencies of 915 and 2450 MHz. To the authors' knowledge, it is the first time PSPICE has been used for SAR and related temperature rise calculation.

This research focused on the effects of low electric current (μE)-assisted sonic agitation of sodium hypochlorite on Enterococcus faecalis infected human root dentin. Extracted human canine roots were instrumented, sterilized, and experimentally contaminated with E. faecalis. After incubation for 21 days, the presence of the biofilm was confirmed by scanning electron microscopy (n = 3). Roots were randomly divided into seven groups according to decontamination procedures: G1: no treatment; G2: sterile saline; G3: 5.25% sodium hypochlorite; G4: passive ultrasonic irrigation; G5: EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) agitation (EA); G6: μE agitation; and G7: μE-assisted sonic agitation. Fixed μE amperage and intensities were applied in G6 and G7. Following microbial sampling, bacterial colonies were counted using the direct plating method. Biofilm was not eradicated in any sample. The μE-assisted sonic agitation of sodium hypochlorite revealed the lowest cfu values (p0.05). Based on available evidence, the following conclusions were drawn: The μE-assisted sonic agitation increased the antibiofilm efficiency of sodium hypochlorite than passive ultrasonic irrigation and EndoActivator. The μE-assisted sonic agitation on 5.25% sodium hypochlorite is not capable to eradicate biofilms at 10mA energy level in 60s.