Browsing by Author "Rouse, Chris D."
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Item An Extra Low-mass Harmonic Radar Transponder for Insect Tracking Applications(IEEE, 2023-06-05) Ala, Ramin; Rouse, Chris D.; Colpitts, Bruce G.The design, construction, and performance of a harmonic radar transponder with a total mass of less than 500 μg is presented. The transponder is intended for insect tracking applications and consists of very fine wire and a small Schottky diode. It is designed for fundamental and harmonic frequencies of 10 GHz and 20 GHz, respectively. Compared to existing harmonic radar transponders, this transponder is easy to construct because the loop inductor can be implemented with a simple bend in the dipole conductor without degrading performance. Through careful design optimization, the conversion loss of the transponder is not impacted by the measures taken to minimize its mass. The expected harmonic power versus the transmitted power is estimated based on the link analysis between the transmitter and receiver of the radar, with the link analysis itself being performed via calculation, harmonic balance simulation, and full-wave simulation. The link analysis simulation predicted a received power of -66.4 dBm for a transmitted power of +22 dBm and a range of 2.4 m. The measured received power level at the harmonic frequency, obtained from the broadside of the transponder in an anechoic test chamber, is approximately -70 dBm, which agrees well with the link analysis. Simulated and measured transponder radiation patterns are also compared and show good agreement. Low-mass transponders such as this enable tracking of smaller insects without reducing their lifespan or compromising their ability to fly at natural altitudes and ranges.Item Conservative analytical assessments of localized RF exposure from small magnetic field sources(Institute of Electrical and Electronics Engineers (IEEE), 2024-04-18) Rouse, Chris D.A conservative analytical framework for assessing radiofrequency (RF) exposure from small magnetic field sources near the body is presented, with an emphasis on the 3kHz to 10MHz frequency range. Worst-case exposure models are proposed and analyzed for both homogeneous and heterogeneous tissue based on source dimensions, drive current, and separation distance. Electromagnetic analysis of induced field enhancements due to tissue heterogeneity is presented. Maximum drive currents for compliance with the basic restrictions are obtained for both tissue models. In the heterogeneous case, field enhancement in thin regions of low conductivity leads to significantly lower allow- able drive levels for nerve stimulation (NS) compliance. Guidance is provided regarding how to account for such enhancements for various internal E-field calculation methods. The impact of these field enhancements on 10-g specific absorption rate (SAR) is found to be small, i.e., the homogeneous tissue assumption appears to be sufficiently conservative. A small enhancement factor may be appropriate for 1-g SAR. The benefit of assessing against the basic restrictions instead of the reference levels is also explored. This work can be leveraged by regulatory and standardization bodies to develop exemption levels for small magnetic field sources, e.g., inductive chargers, to significantly reduce compliance burdens.Item Detection of misalignment and foreign objects in resonant capacitive power transfer(University of New Brunswick, 2023-10) Herpers, Christian; Rouse, Chris D.Wireless power transfer has gained interest in recent years due to the increase in the number of mobile electronic devices and systems needing to be charged. Capacitive power transfer (CPT) offers a low-cost option for medium- and high-power charging. To ensure safe and reliable power transfer, foreign objects and misalignments must be detected. Furthermore, exposure of living tissue to high electromagnetic fields (EMFs) must be avoided. This work presents CPT detection methods for both lateral misalignment and foreign objects (FOs). Symmetries of capacitance matrices are studied to distinguish between types of misalignment and FOs. Results were generated via simulation and verified with measurements on a laboratory 13.56 MHz CPT link. FO detection also functions under lateral misalignment, is parameter-based, and is achieved without external circuitry or sensors. Results indicate the direction of lateral misalignment. EMF exposure was simulated to ensure kW-range power transmission while meeting international safety guidelines.Item Lateral Misalignment and Foreign Object Detection in Resonant Capacitive Power Transfer(IEEE, 2023-08-22) Herpers, Christian; Rouse, Chris D.This paper proposes a method of detecting lateral misalignment and foreign objects in a resonant capacitive power transfer (RCPT) system. Foreign object detection (FOD) under misalignment is also considered. The method considers the admittance matrices associated with a practical RCPT link and leverages voltage measurements on the transmit-side for detection. To support this work, a 13.56MHz RCPT link in- corporating a six-plate structure was designed and built for electric vehicle charging applications. A matching simulation model was created and, when evaluating FOD, metallic and tissue-simulating foreign objects were added. Simulations, val- idated by measurements, show that a lateral misalignment of up to 170mm can be identified, including the direction of misalignment. FOD simulations indicate a detection range of up to 380 mm, also including direction. Further simulations indicate that the detection range surpasses the distance at which the basic restrictions for electromagnetic field exposure would be exceeded. Additionally, simulation results show that foreign objects can be detected under misalignment. Thus, both lateral misalignment detection and FOD can be achieved without the use of external sensors. This work can help to advance the safety features of RCPT at minimal cost for important applications such as electric vehicle charging and electrified roadways.