The measurement of the dielectric properties of high-permittivity materials at centimetre wavelengths
作者:
J.G.Powles,
WillisJackson,
期刊:
Proceedings of the IEE - Part III: Radio and Communication Engineering
(IET Available online 1949)
卷期:
Volume 96,
issue 43
页码: 383-389
年代: 1949
DOI:10.1049/pi-3.1949.0085
出版商: IEE
数据来源: IET
摘要:
The paper gives the results of room-temperature measurements on ceramic (polycrystalline) specimens of magnesium, calcium, strontium and barium titanates at frequencies of 1.5 and 9450 Mc/s (3.18 cm), and on barium titanate at 24000 Mc/s (1.25 cm). It is found that the latter material is unique among this series in showing a considerable fall in permittivity, and a large increase in the loss tangent, at the higher frequencies, compared with the behaviour at 1.5 Mc/s. Variable temperature measurements on barium titanate show that the crystallo-graphic change which is known to occur around 120°C, the Curie point of the material, affects the permittivity at 9450 and 1.5 Mc/s in an analogous manner.Room-temperature measurements at the same frequencies on a range of barium-strontium titanate compositions are also described, and attention is drawn to the composition 56% BaTiO3: 44% SrTiO3, having a permittivity of 760 and loss tangent of 0.02 at 9450 Mc/s and 20°C, as likely to be of value in microwave work.The difficulties associated with the measurement of high-permittivity values at centimetre wavelengths are discussed, and a full description is given of the three methods developed for different parts of the investigation.
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