Electromagnetic Energy Harvesting In Pursuit of Heat Radiation
AuthorBean, Richard Allan
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This dissertation explores the potential harvesting of electrical energy from heat radiation. Heat is an abundant form of energy that occurs naturally. It is spontaneously emitted from the matter in a material surface, and its random photonic emissions aggregate. It is transferred from material surfaces to other material surfaces in the form of heat radiation. This heat radiation transfers through free space in the form of plane waves. These plane waves are electromagnetic in character and are fully described by Maxwell’s equations.Electromagnetic (EM) plane waves are routinely utilized in communication, radar, and optical systems. This dissertation posits that heat radiation can be captured by antennas, conducted by coax cables, and then converted to hybrid TE-TM waves inside microstrip printed circuit boards. These EM waves can be subsequently rectified using electronic devices known as Schottky diodes. The resultant direct current (DC) can be stored and used to power electronic devices and electrical machinery.This dissertation analyzes the theoretical foundations of heat radiation. Using Planck’s Law, the likely power magnitudes from material surfaces are predicted. Passive antennas, geometrical relationships, and bandwidth aggregation can concentrate these power magnitudes. Using these passive gains, effective rectification can be achieved.Complementing this mathematical and logical analysis, physical measurements of power were made for multiple antennas types, for different temperatures, and for different distances from the material surfaces. Multiple power meters and measurement applications were used.To confirm the feasibility of harvesting electrical energy from heat radiation multiple rectifier and rectenna designs and circuits were designed, fabricated, and tested. Prevailing views of energy aggregation were adopted and then compared with the actual performance in the electronic circuits.Finally, the applied research in this dissertation has successfully generated DC electricity by harvesting ambient radiation using electrical engineering technology and techniques. Because photons of heat radiation are indistinguishable from the photons from other sources in the microwave frequency range, this dissertation logically examines the potential sources removing the increasingly improbable sources such that heat radiation remains a likely source. Further, the harvesting technology was tested in an anechoic chamber where the manmade radiation sources from outside the chamber were greatly reduced by metallic shielding and signal absorbing materials.