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Shielding effectiveness of electromagnetic energy from 50-ohm radio frequency heating system for disinfestation of stored grains
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.orgCitation: 2018 ASABE Annual International Meeting 1801004.(doi:10.13031/aim.201801004)
Authors: R.J Macana, T. T. Moirangthem, O.D. Baik
Keywords: Disinfestation, Electric fields, Electromagnetic energy, Insect pests, Magnetic fields, Microwave, Radio frequency, Radio waves, RF shielding, Stored grains
Electromagnetic radiation shielding in 50-ohm radio frequency heating systems, also known as RF shielding is significant for the safety of the workers and the equipment. The understanding of the electromagnetic radiation and behavior of waves, frequency, wavelength, energy, electric fields, magnetic fields, and power density of radio frequency heater is presented in this paper. Radio frequency leakage composed of electric and magnetic fields. High exposure to these fields can be dangerous to people because of its thermal effects to the body, especially to thermolabile parts. Therefore, RF shielding is critically important and it can be assessed through its electric and magnetic fields intensity and power density. The electric fields, magnetic fields, and power density increase when increasing the power applied to the load and decrease when increasing the distance from the RF energy source. The aluminum metal sheet is preferred as RF shielding material for industrial level applications over expanded steel metal because of its high conductivity and low resistance. However, steel can be used as an alternative to aluminum at a certain power level. Furthermore, it is suggested that in designing an RF shielding cage for high power applications: all sides should be covered; gaps and holes should be avoided; conductor materials around/inside the cage should be removed/grounded; cage should be grounded, and in good contact with all parts (bolts, joints, doors, etc.). Current should flow smoothly at all parts of the shield cage going to the ground for a successful RF shielding.(Download PDF) (Export to EndNotes)