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{{see also|Distributed element filter#History|Waveguide filter#History|Planar transmission line#History}}
[[File:Heaviside face.jpg|thumb|upright|alt=Photo of a bearded, middle-aged Oliver Heaviside|Oliver Heaviside]]
Distributed element modelling was first used in electrical network analysis by [[Oliver Heaviside]]<ref>Heaviside (1925)</ref> in 1881. Heaviside used it to find a correct description of the behaviour of signals on the [[transatlantic telegraph cable]]. Transmission of early transatlantic telegraph had been difficult and slow due to [[dispersion (optics)|dispersion]], an effect which was not well understood at the time. Heaviside's analysis, now known as the [[telegrapher's equations]], identified the problem and suggested<ref>Heaviside (1887)</ref> [[loading coil|methods for overcoming it]]. It remains the standard analysis of transmission lines.<ref>Brittain, p. 39</ref>
[[Warren P. Mason]] was the first to investigate the possibility of distributed element circuits, and filed a patent<ref>Mason (1930)</ref> in 1927 for a coaxial filter designed by this method. Mason and Sykes published the definitive paper on the method in 1937. Mason was also the first to suggest a distributed element acoustic filter in his 1927 doctoral thesis, and a distributed element mechanical filter in a patent<ref>Mason (1961)</ref> filed in 1941. The acoustic work had come first, and Mason's colleagues in the [[Bell Labs]] radio department asked him to assist with coaxial and waveguide filters.<ref>{{multiref|Johnson ''et al.'' (1971), p. 155|Fagen & Millman, p. 108|Polkinghorn (1973)}}</ref>
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Planar formats began to be used with the invention of [[stripline]] by [[Robert M. Barrett]]. Although stripline was another wartime invention, its details were not published<ref>Barrett & Barnes (1951)</ref> until 1951. [[Microstrip]], invented in 1952,<ref>Grieg and Englemann (1952)</ref> became a commercial rival of stripline; however, planar formats did not start to become widely used in microwave applications until better dielectric materials became available for the substrates in the 1960s.<ref>Bhat & Koul, p. 3</ref> Another structure which had to wait for better materials was the dielectric resonator. Its advantages (compact size and high quality) were first pointed out<ref>Richtmeyer (1939)</ref> by R. D. Richtmeyer in 1939, but materials with good temperature stability were not developed until the 1970s. Dielectric resonator filters are now common in waveguide and transmission line filters.<ref>Makimoto & Yamashita, pp. 1–2</ref>
Important theoretical developments included [[Paul I. Richards]]' [[commensurate line theory]], which was published<ref>Richards (1948)</ref> in 1948, and [[Kuroda's identities]], a set of
== References ==
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