Physics:Electromagnetic absorbers
Electromagnetic absorbers are specifically chosen or designed materials that can inhibit the reflection or transmission of electromagnetic radiation. For example, this can be accomplished with materials such as dielectrics combined with metal plates spaced at prescribed intervals or wavelengths. The particular absorption frequencies, thickness, component arrangement and configuration of the materials also determine capabilities and uses. In addition, researchers are studying advanced materials such as metamaterials in hopes of improved performance and diversity of applications. Some intended applications for the new absorbers include emitters, sensors, spatial light modulators, infrared camouflage, wireless communication, and use in thermophotovoltaics.[1][2][3]
Generally, there are two types of absorbers: resonant absorbers and broadband absorbers. The resonant absorbers are frequency-dependent because of the desired resonance of the material at a particular wavelength. Different types of resonant absorbers are the Salisbury screen, the Jaumann absorber, the Dallenbach layer, crossed grating absorbers, and circuit analog (CA) absorbers.
Broadband absorbers are independent of a particular frequency and can therefore be effective across a broad spectrum.[4]
References
- ↑ Alici, Kamil Boratay; Bilotti, Filiberto; Vegni, Lucio; Ozbay, Ekmel (2010). "Experimental verification of metamaterial based subwavelength microwave absorbers" (Free PDF download). Journal of Applied Physics 108 (8): 083113–083113–6. doi:10.1063/1.3493736. Bibcode: 2010JAP...108h3113A. http://www.fen.bilkent.edu.tr/~bora/articles/article21_alici_JAP_2010.pdf.
- ↑ Watts, Claire M.; Liu, Xianliang; Padilla, Willie J. (2012). "Metamaterial Electromagnetic Wave Absorbers". Advanced Materials 24 (23): OP98–OP120. doi:10.1002/adma.201200674. PMID 22627995. Bibcode: 2012AdM....24P..98W.
- ↑ Alici, Kamil Boratay; Turhan, Adil Burak; Soukoulis, Costas M.; Ozbay, Ekmel (2011). "Optically thin composite resonant absorber at the near-infrared band: A polarization independent and spectrally broadband configuration" (Free Article download). Optics Express 19 (15): 14260–7. doi:10.1364/OE.19.014260. PMID 21934790. Bibcode: 2011OExpr..1914260B. http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-19-15-14260.
- ↑ Knott, Eugene F; John F Shaeffer and Michael T Tuley (2004). Radar Cross Section. SciTech Radar and Defense series (Second ed.). Raleigh, NC: SciTech Publishing. pp. 9–11, 271, 298, 313, 334, 339, 531. ISBN 9781891121258. https://books.google.com/books?id=0WuGjb8sqCUC&dq=1.5+Absorbing+Materials&pg=PA9.
Further reading
- Munk, Benedikt A. (2000). Frequency Selective Surfaces: Theory and Design. New York: John Wiley & Sons. pp. 315–317. ISBN 978-0-471-37047-5. https://books.google.com/books?id=9pNMhRQrpScC&pg=PA315. The Salisbury screen, invented by American engineer Winfield Salisbury in 1952.
- Salisbury W. W. "Absorbent body for electromagnetic waves", United States patent number 2599944 June 10, 1952. Also cited in Munk
- Baker-Jarvis, James; Kim, Sung (2012). "The Interaction of Radio-Frequency Fields with Dielectric Materials at Macroscopic to Mesoscopic Scales" (Free PDF download). Journal of Research of the National Institute of Standards and Technology 117: 1–60. doi:10.6028/jres.117.001. PMID 26900513. PMC 4553869. http://nvlpubs.nist.gov/nistpubs/jres/117/jres.117.001.pdf.
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