極低頻：修订间差异
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[[File:Clam Lake ELF.jpg|thumb|ELF 發射設備]] |
[[File:Clam Lake ELF.jpg|thumb|ELF 發射設備]] |
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'''極低頻'''（'''E'''xtremely '''L'''ow '''F'''requency，'''ELF'''）<ref>{{cite web |url=http://terms.naer.edu.tw/detail/2367394/|title=極低頻率，超低頻|work=國家教育研究院 |accessdate=2019-04-03}}</ref>是指[[頻率]]由3Hz至30Hz<ref name="ITU Nomenclature">{{cite web |title=Rec. ITU-R V.431-7, Nomenclature of the frequency and wavelength bands used in telecommunications |url=http://www.itu.int/dms_pubrec/itu-r/rec/v/R-REC-V.431-7-200005-I!!PDF-E.pdf |publisher=ITU |accessdate=20 February 2013 |deadurl=yes |archiveurl=https://web.archive.org/web/20131031020427/http://www.itu.int/dms_pubrec/itu-r/rec/v/R-REC-V.431-7-200005-I%21%21PDF-E.pdf |archivedate=31 October 2013 }}</ref>，[[波長]]10,000公里至100,000公里的[[無線電波]]<ref>{{cite web |url=http://www.nasa.gov/directorates/heo/scan/communications/outreach/funfacts/txt_band_designators_prt.htm |publisher=NASA |title=Extremely Low Frequency |work=ANL Glossary |accessdate=28 September 2013}}</ref><ref>{{cite web |url=http://www.solareis.anl.gov/glossacro/dsp_wordpopup.cfm?word_id=4668 |title=Extremely low frequency |work=ANL Glossary |accessdate=9 August 2011}}</ref> |
'''極低頻'''（'''E'''xtremely '''L'''ow '''F'''requency，'''ELF'''）<ref>{{cite web |url=http://terms.naer.edu.tw/detail/2367394/|title=極低頻率，超低頻|work=國家教育研究院 |accessdate=2019-04-03}}</ref>是指[[頻率]]由3Hz至30Hz<ref name="ITU Nomenclature">{{cite web |title=Rec. ITU-R V.431-7, Nomenclature of the frequency and wavelength bands used in telecommunications |url=http://www.itu.int/dms_pubrec/itu-r/rec/v/R-REC-V.431-7-200005-I!!PDF-E.pdf |publisher=ITU |accessdate=20 February 2013 |deadurl=yes |archiveurl=https://web.archive.org/web/20131031020427/http://www.itu.int/dms_pubrec/itu-r/rec/v/R-REC-V.431-7-200005-I%21%21PDF-E.pdf |archivedate=31 October 2013 }}</ref>，[[波長]]10,000公里至100,000公里的[[無線電波]]<ref>{{cite web |url=http://www.nasa.gov/directorates/heo/scan/communications/outreach/funfacts/txt_band_designators_prt.htm |publisher=NASA |title=Extremely Low Frequency |work=ANL Glossary |accessdate=28 September 2013}}</ref><ref>{{cite web |url=http://www.solareis.anl.gov/glossacro/dsp_wordpopup.cfm?word_id=4668 |title=Extremely low frequency |work=ANL Glossary |accessdate=9 August 2011}}</ref> 。 |
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極低頻[[無線電波]]是[[閃電]]和自然擾動在[[地球磁場]]中產生的，因此是[[大氣科學]]中研究的主題之一。由於難以製造可以輻射這種長波的[[天線]]，因此極低頻[[無線電波]]極少用於[[通信]]系統中。ELF波可以穿透[[海水]]，這使它們可以用於與[[潛艇]]的通信。美國、俄羅斯、印度和中國是目前僅有已知建造ELF通信設施的國家。<ref name="NavyFactSheet">{{cite web |title=Extremely Low Frequency Transmitter Site, Clam Lake, Wisconsin |work=Navy Fact File |publisher=United States Navy |date=28 June 2001 |url=http://www.fas.org/nuke/guide/usa/c3i/fs_clam_lake_elf2003.pdf |format= |doi= |accessdate=17 February 2012}} at the [http://www.fas.org/ Federation of American Scientists website]</ref><ref name="Wolkoff">{{cite conference |first=E. A. |last=Wolkoff |author2=W. A. Kraimer |title=Pattern Measurements of U.S. Navy ELF Antennas |booktitle=ELF/VLF/LF Radio Propagation and Systems Aspects |pages=26.1–26.10 |publisher=AGARD Conference proceedings 28 Sept. – 2 Oct. 1992, NATO |date=May 1993 |location=Belgium |url=http://www.dtic.mil/dtic/tr/fulltext/u2/a267991.pdf |doi= |id= |accessdate=17 February 2012}}</ref><ref name="Coe">{{cite book |last=Coe |first=Lewis |title=Wireless Radio: A brief history |publisher=McFarland |year=2006 |location=USA |pages=143–144 |url=https://books.google.com/?id=W1JAeg1PiWIC&pg=PA143&dq=%22extremely+low+frequency%22+ELF+propagation+waveguide#v=onepage&q=%22extremely%20low%20frequency%22%20ELF%20propagation%20waveguide&f=false |doi= |id= |isbn=978-0786426621}}</ref><ref name="Sterling">{{cite book |last=Sterling |first=Christopher H. |title=Military communications: from ancient times to the 21st century |publisher=ABC-CLIO |year=2008 |location= |pages=431–432 |url=https://books.google.com/?id=RBC2nY1rp5MC&printsec=frontcover#v=snippet&q=zevs&f=false |doi= |id= |isbn=978-1851097326}}</ref><ref name="Bashkuev">{{cite journal |last=Bashkuev |first=Yu. B. |author2=V. B. Khaptanov |author3=A. V. Khankharaev |title=Analysis of Propagation Conditions of ELF Radio Waves on the "Zeus"–Transbaikalia Path |journal=Radiophysics and Quantum Electronics |volume=46 |issue=12 |pages=909–917 |date=December 2003 |issn= |doi=10.1023/B:RAQE.0000029585.02723.11 |id= |bibcode = 2003R&QE...46..909B }}</ref><ref name="Trond">{{cite web |last=Jacobsen |first=Trond |title=ZEVS, The Russian 82 Hz ELF Transmitter |work=Radio Waves Below 22 kHz |publisher=Renato Romero webpage |year=2001 |url=http://www.vlf.it/zevs/zevs.htm |doi= |accessdate=17 February 2012}}</ref><ref name="janes">{{cite web |last1=Hardy |first1=James |title=India makes headway with ELF site construction |url=http://www.janes.com/article/11147/india-makes-headway-with-elf-site-construction |publisher=[[Jane's Information Group|IHS Jane's Defence Weekly]] |accessdate=23 February 2014 |archiveurl=https://web.archive.org/web/20140223135343/http://www.janes.com/article/11147/india-makes-headway-with-elf-site-construction |archivedate=23 February 2014 |date=28 February 2013}}</ref><ref name="toi14">{{cite web |url=http://timesofindia.indiatimes.com/india/Navy-gets-new-facility-to-communicate-with-nuclear-submarines-prowling-underwater/articleshow/39371121.cms |title=Navy gets new facility to communicate with nuclear submarines prowling underwater |date=31 July 2014 |work=[[The Times of India]]}}</ref> |
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而多數給[[美國海軍]]及[[俄羅斯海軍]]用作和[[潛艇]]溝通。 |
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==應用== |
==應用== |
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2019年4月3日 (三) 08:32的版本
極低頻（Extremely Low Frequency，ELF）[1]是指頻率由3Hz至30Hz[2]，波長10,000公里至100,000公里的無線電波[3][4] 。
極低頻無線電波是閃電和自然擾動在地球磁場中產生的，因此是大氣科學中研究的主題之一。由於難以製造可以輻射這種長波的天線，因此極低頻無線電波極少用於通信系統中。ELF波可以穿透海水，這使它們可以用於與潛艇的通信。美國、俄羅斯、印度和中國是目前僅有已知建造ELF通信設施的國家。[5][6][7][8][9][10][11][12]
應用
基於無線電於鹹水的傳送特性，除了極低頻和超低頻外，通常無線電波不容易在海中傳送。雖然它可以在水中容易地傳送，但是ELF每分鐘可以傳送的訊號相對地較小，所以只是給美軍用作指示潛水艇進入／離開海底。另外要有效傳送極低頻信號需要大型的天線，所以極低頻的使用不太普遍。
一些國家的電氣化鐵路使用低於一般50/60 Hz工頻的極低頻交流電，例如德國、奧地利、瑞士、挪威和瑞典使用15,000V 16.67Hz，美國使用11,000V或12,500V 25Hz的交流電。
参考文献
- ^ 極低頻率，超低頻. 國家教育研究院. [2019-04-03].
- ^ Rec. ITU-R V.431-7, Nomenclature of the frequency and wavelength bands used in telecommunications (PDF). ITU. [20 February 2013]. （原始内容 (PDF)存档于31 October 2013）.
- ^ Extremely Low Frequency. ANL Glossary. NASA. [28 September 2013].
- ^ Extremely low frequency. ANL Glossary. [9 August 2011].
- ^ Wolkoff, E. A.; W. A. Kraimer. Pattern Measurements of U.S. Navy ELF Antennas (PDF). ELF/VLF/LF Radio Propagation and Systems Aspects. Belgium: AGARD Conference proceedings 28 Sept. – 2 Oct. 1992, NATO: 26.1–26.10. May 1993 [17 February 2012].
- ^ Coe, Lewis. Wireless Radio: A brief history. USA: McFarland. 2006: 143–144. ISBN 978-0786426621.
- ^ Sterling, Christopher H. Military communications: from ancient times to the 21st century. ABC-CLIO. 2008: 431–432. ISBN 978-1851097326.
- ^ Bashkuev, Yu. B.; V. B. Khaptanov; A. V. Khankharaev. Analysis of Propagation Conditions of ELF Radio Waves on the "Zeus"–Transbaikalia Path. Radiophysics and Quantum Electronics. December 2003, 46 (12): 909–917. Bibcode:2003R&QE...46..909B. doi:10.1023/B:RAQE.0000029585.02723.11.
- ^ Jacobsen, Trond. ZEVS, The Russian 82 Hz ELF Transmitter. Radio Waves Below 22 kHz. Renato Romero webpage. 2001 [17 February 2012].
- ^ Hardy, James. India makes headway with ELF site construction. IHS Jane's Defence Weekly. 28 February 2013 [23 February 2014]. （原始内容存档于23 February 2014）.
- ^ Navy gets new facility to communicate with nuclear submarines prowling underwater. The Times of India. 31 July 2014.
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