Modelling and Analysis of Power Distribution of Electromagnetic Waves on Plane Surfaces Using Lock-in IR Thermography
TL;DR: In this article, a thin screen made of carbon fiber reinforced polymers is placed in front of a microwave source, where the electromagnetic waves impinging on the screen are partially absorbed, resulting in temperature rise of the screen.
Abstract: The electric field distribution (magnitude only) near a radiating source (antenna) can be easily determined using infrared thermography. A thin screen (made of carbon fiber reinforced polymers) is placed in front of a microwave source. The electromagnetic waves impinging on the screen are partially absorbed, resulting in temperature rise of the screen. This temperature rise is monitored by an infrared camera. The temperature distribution thus observed is mapped to the electric field strength (magnitude of electric field) of the electromagnetic waves. Points on the screen where the temperature rise is low correspond to weak electromagnetic fields whereas points with high temperature rise correspond to strong electromagnetic fields. In this paper electro-thermal modelling is done so as to obtain the temperature distribution over the screen, when an electromagnetic field is incident on it. This model can conversely be used for finding electromagnetic field distributions from IR thermal images.
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TL;DR: In this article, the infrared glow in fan-shaped boreholes was studied and measured along four cardinal directions and in vertical direction in block 12, northwestern site, sublevel 6, horizon minus 210, the Tashtagol iron ore mine.
Abstract: Infrared glow in fan-shaped boreholes was studied and measured along four cardinal directions and in vertical direction in block 12, northwestern site, sublevel 6, horizon minus 210, the Tashtagol iron ore mine. It is shown that the difference in the glow temperature can reach 3° C in the eastern direction and in vertical fan-shaped boreholes. The results were obtained for physical modeling of the glow in the holes of the magnetite ore samples. The patterns of changes in the intensity of infrared glow of the magnetite ore samples under uniaxial or shear compression are shown. The changes in the infrared glow temperature are found to correspond to the stages of fracture development. In this case, the temperature of the IR glow changes in accordance with the stages of fracture development. Changes in the electromagnetic emission are given in accordance with the stages of preparation and development of fracture of the magnetite ore sample of similar structure. Possible mechanisms of energy supply for heating rocks in the vicinity of boreholes and holes are discussed. The data obtained indicate the efficiency of IR thermometry for detection of stressed rock massif areas in the vicinity of boreholes with increased glow intensity.
5 citations
TL;DR: In this article, a metasurface consisting of thermally isolated elements of low mass and highly emissive material for maximal IR conversion of the incident wave is used to measure low power electromagnetic fields from mm-wave devices.
Abstract: We have developed a technique to measure low-power electromagnetic fields from mm-wave devices non-intrusively by combining a metasurface, designed to absorb power and focus the radiated power in a thermally isolated region, with an infrared (IR) camera. The metasurface consists of thermally isolated elements of low mass and highly emissive material for maximal IR conversion of the incident wave. The IR camera captures the converted energy and indirectly images the incident electromagnetic field on the metasurface. The setup combines multi-scale, multi-physical processes to conduct measurements of the incident electromagnetic fields in real time. In this work, the technique is presented and discussed. Measurements are carried out to demonstrate the technique and image the electromagnetic field of a radiating device. The results compare well with simulations, and the technique can measure the low power density levels of consumer devices and provide a general visualization of electromagnetic fields in a live setting.
2 citations
Cites background or methods from "Modelling and Analysis of Power Dis..."
...1mW/cm2, compared to previous measurements in the range of 27-220mW/cm2 for frequencies in the 2-20GHz range [9, 17, 19, 20]....
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...This stands in contrast to generating a temperature increase over the entire sheet [3, 6, 22] or patches [16], which use high power density levels, 27-220mW/cm2 for frequencies in the 2-20GHz range [9, 17, 19, 20]....
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...The purpose is to convert electromagnetic radiation to detectable infrared photons [3, 6, 11, 16, 17, 19, 20, 21, 22, 23]....
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References
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Book•
31 Dec 1959
TL;DR: In this paper, a classic account describes the known exact solutions of problems of heat flow, with detailed discussion of all the most important boundary value problems, including boundary value maximization.
Abstract: This classic account describes the known exact solutions of problems of heat flow, with detailed discussion of all the most important boundary value problems.
21,807 citations
Book•
01 Jan 1996
TL;DR: In this article, the photothermal effect is used to generate thermal wave non-destructive evaluation, which is then used for the measurement of semiconducting materials and their properties.
Abstract: Introduction. History. Overview. Thermal waves. Optical generation of thermal waves - photothermal effect. Instrumentation and detection techniques. Transient thermal phenomena. Photoacoustic spectroscopy and its applications. Thermal wave non-destructive evaluation. Characterization of semiconducting materials. Thermal property measurement. Monitoring and measurement of gases and the atmosphere.
506 citations
TL;DR: A brief history of the various techniques used to obtain thermal images of electromagnetic fields is first presented in this article, where an analysis of the thermal problems involved is presented, and the solution to these problems is the key for the enhancement of the technique and for really quantitative work.
38 citations
TL;DR: In this article, an intensity-modulated laser beam is focused to make a small heat spot on the front side of a thin-plate specimen and the excited temperature waves are detected by a thin thermocouple attached onto its rear side.
Abstract: A new technique to measure thermal diffusivities of solid materials, including their anisotropic behaviours, has been developed. The technique is based on periodic heating: an intensity-modulated laser beam is focused to make a small heat spot on the front side of a thin-plate specimen and the excited temperature waves are detected by a thin thermocouple attached onto its rear side. The phase lag of temperature waves is monitored as a function of the distance between the heated spot and the sensing point. The accuracy and the applicability of the present technique were well verified by using two kinds of isotropic reference samples, an austenitic stainless steel and pure copper. The typical uncertainty is estimated to be 5% at room temperature. This technique was applied to evaluate the highly anisotropic thermal diffusivity of highly oriented pyrolytic graphite (HOPG). Its anisotropy, Dab/Dc (the ratio of the in-plane thermal diffusivity to the out-of-plane one), was observed to be about 220.
27 citations
TL;DR: In this paper, a lock-in thermographic system was used to monitor the electromagnetic field by modulating the amplitude of the interference field and a multimode field inside a waveguide.
Abstract: Electromagnetic fields can be monitored by infrared thermography, using sensitive paints or coatings deposited on structures or thin films. Enhancement of the method by release of convective losses and conduction effects is demonstrated. This is obtained by modulating the amplitude of the fields and using a lock-in thermographic system. Examples of application are given which concern an interference field and a multimode field inside a wave-guide.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
24 citations