Editing Spark-gap transmitter (section)

====Disadvantages====
[[File:Marconi spark gap transmitter 1896.svg|thumb|Circuit of Marconi's monopole transmitter and all other transmitters prior to 1897.]]

The primitive transmitters prior to 1897 had no [[resonant circuit]]s (also called LC circuits, tank circuits, or tuned circuits), the spark gap was in the antenna, which functioned as the resonator to determine the frequency of the radio waves.<ref name="Beauchamp1"/><ref name="Nahin5">Nahin, Paul J. (2001) ''[https://books.google.com/books?id=V1GBW6UD4CcC&pg=PA46&dq=spark The Science of Radio: with MATLAB and Electronics Workbench demonstrations, 2nd Ed.]'', p. 46</ref><ref name="Sarkar" />{{rp|p.352-353, 355-358}}<ref name="Thrower">{{cite conference
| last1= Thrower
| first1= K. R.
| title= History of tuning
| conference= Proceedings of the 1995 International Conference on 100 Years of Radio
| publisher= Institute of Engineering Technology
| date= 5 September 1995
| location= London
| url= https://ieeexplore.ieee.org/document/491801
| doi= 10.1049/cp:19950799
| isbn= 0-85296-649-0
| access-date= 20 June 2018| url-access= subscription
}} [https://www.nonstopsystems.com/radio/pdf-hell/article-IC-1995-Thrower.pdf archived]</ref> These were called "unsyntonized" or "plain antenna" transmitters.<ref name="Sarkar" />{{rp|p.352-353, 355-358}}<ref name="Marriott1">{{cite journal
| last1= Marriott
| first1= Robert H.
| title= United States Radio Development
| journal= Proceedings of the I.R.E.
| volume= 5
| issue= 3
| pages= 179–188
| date= June 1917
| url= https://books.google.com/books?id=NNU1AQAAMAAJ&q=%22plain+antenna%22+%22coupled+circuit%22+transmitter&pg=PA189
| access-date= 8 March 2018}}</ref>

The average power output of these transmitters was low, because due to its low capacitance the antenna was a highly [[damping ratio|damped]] oscillator (in modern terminology, it had very low [[Q factor]]).<ref name="Aitken2014">{{cite book
| last1= Aitken
| first1= Hugh G.J.
| title= The Continuous Wave: Technology and American Radio, 1900-1932
| publisher= Princeton University Press
| date= 2014
| url= https://books.google.com/books?id=ebr_AwAAQBAJ&pg=PA3
| isbn= 978-1400854608
}}</ref>{{rp|p.4–7, 32–33}} During each spark the energy stored in the antenna was quickly radiated away as radio waves, so the oscillations decayed to zero quickly.<ref name="Ashley1">[https://books.google.com/books?id=pK-EAAAAIAAJ&pg=PA34 Ashley, Hayward (1912) ''Wireless Telegraphy and Wireless Telephony: An understandable presentation of the science of wireless transmission of intelligence''], p. 34-36</ref> The radio signal consisted of brief pulses of radio waves, repeating tens or at most a few hundreds of times per second, separated by comparatively long intervals of no output.<ref name="Sarkar" />{{rp|p.352-353, 355-358}} The power radiated was dependent on how much [[electric charge]] could be stored in the antenna before each spark, which was proportional to the [[capacitance]] of the antenna. To increase their capacitance to ground, antennas were made with multiple parallel wires, often with capacitive toploads, in the "harp", "cage", "[[umbrella antenna|umbrella]]", "inverted-L", and "[[T-antenna|T]]" antennas characteristic of the "spark" era.<ref name="CodellaAerials">{{cite web
| last= Codella
| first= Christopher F.
| title= Aerials, Attachments, and Audibility
| work= Ham Radio History
| publisher= Codella's private website
| date= 2016
| url= http://w2pa.net/HRH/aerials-attachments-and-audibility/
| access-date= 22 May 2018}}</ref> The only other way to increase the energy stored in the antenna was to charge it up to very high voltages.<ref name="Jansky1">{{cite book
| last1= Jansky
| first1= Cyril Methodius
| title= Principles of Radiotelegraphy
| publisher= McGraw-Hill Book Co.
| date= 1919
| location= New York
| pages= [https://archive.org/details/principlesradio01jansgoog/page/n179 165]–167
| url= https://archive.org/details/principlesradio01jansgoog
}}</ref><ref name="Sarkar" />{{rp|p.352-353, 355-358}} However the voltage that could be used was limited to about 100&nbsp;kV by [[corona discharge]] which caused charge to leak off the antenna, particularly in wet weather, and also energy lost as heat in the longer spark.

[[File:Spark gap transmitter bandwidth - A.png |thumb |right |Emission bandwidth of a spark gap transmitter showing signal strength versus wavelength in meters]]
A more significant drawback of the large [[damping ratio|damping]] was that the radio transmissions were electrically "noisy"; they had a very large [[bandwidth (signal processing)|bandwidth]].<ref name="CodellaSparkRadio"/><ref name="Hong" />{{rp|p.90-93}}<ref name="Beauchamp1"/><ref name="Aitken1985"/>{{rp|72-75}} These transmitters did not produce waves of a single [[frequency]], but a continuous band of frequencies.<ref name="Aitken1985">{{cite book |last1= Aitken |first1= Hugh G.J. |title= Syntony and Spark: The Origins of Radio |publisher= Princeton Univ. Press |date= 1985 |url= https://books.google.com/books?id=Mez_AwAAQBAJ&q=Fourier+noise&pg=PA72 |isbn= 978-1400857883}}</ref>{{rp|72-75}}<ref name="Hong" />{{rp|p.90-93}} They were essentially [[radio noise]] sources radiating energy over a large part of the [[radio spectrum]], which made it impossible for other transmitters to be heard.<ref name="Kennedy"/> When multiple transmitters attempted to operate in the same area, their broad signals overlapped in frequency and [[radio frequency interference|interfered]] with each other.<ref name="Beauchamp1"/><ref name="Thrower"/> The [[radio receiver]]s used also had no resonant circuits, so they had no way of selecting one signal from others besides the broad resonance of the antenna, and responded to the transmissions of all transmitters in the vicinity.<ref name="Thrower"/> An example of this interference problem was an embarrassing public debacle in August 1901 when Marconi, [[Lee de Forest]], and [[Greenleaf Whittier Pickard|G. W. Pickard]] attempted to report the New York Yacht Race to newspapers from ships with their untuned spark transmitters.<ref name="Lee3">[https://books.google.com/books?id=io1hL48OqBsC&pg=PA6&dq=%22yacht+race%22 Lee, Thomas H. 2004 ''The Design of CMOS Radio-Frequency Integrated Circuits, 2nd Ed.'', p. 6-7]</ref><ref name="Howeth1">{{cite book
| last1= Howeth
| first1= L. S.
| title= The History of Communications - Electronics in the U.S. Navy
| publisher= U.S. Navy
| date= 1963
| pages= [https://archive.org/details/historyofcommuni00howe/page/38 38]–39
| url= https://archive.org/details/historyofcommuni00howe
}}</ref><ref name="ElectricalWorld1901">{{cite journal
| title= Reporting the yacht races by wireless telegraph
| journal= Electrical World
| volume= 38
| issue= 15
| pages= 596–597
| date= October 12, 1901
| url= https://books.google.com/books?id=ntlQAAAAYAAJ&q=%22De+forest%22+marconi+interference&pg=PA596
| access-date= 8 March 2018}}</ref> The Morse code transmissions interfered, and the reporters on shore failed to receive any information from the garbled signals.
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