Here is the abstract you requested from the IMAPS_2007 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Dielectric Material Characterisation above 100GHz using the Microstrip Ring Resonator|
|Keywords: Dielectric measurement, Materials testing, Microstrip resonators|
|The microstrip ring resonator is commonly used to determine electronic material properties at microwave frequencies, and is able to give accurate information about both the dielectric constant and losses. At frequencies above 60GHz, it has been found that some materials still offer acceptable performance. Information about the characteristics of printed circuit materials at millimetre-wave frequencies is scarce, due to the difficulty of making the circuits at a necessarily high resolution, and lack of familiar measurement techniques. This work describes practical measurements made on a variety of microwave substrates using ring resonators specifically designed for very high operating frequencies. As well as covering the basic theory of the resonators, this work focuses on problems which occur due to the very small wavelength above 100GHz and difficulties in feeding the resonators. A new technique of direct coupling to the resonator is described which does not require a small coupling gap and offers some accuracy enhancements over traditional ring resonators. Test circuits have been fabricated on a flexible polymer plastic substrate which shows usable performance beyond 120GHz. In addition, two types of thick film photoimagable dielectric have been used to make multilayer microstrip circuits, and measurements on resonators also show promise for millimetre-wave circuits. Very high line resolution is required to fabricate microstrip circuits above 100GHz, and imperfections in the lines can cause resonances to split. The phenomena is discussed and it is shown what causes this effect, how if affects measurements. Finally, a discussion on the sources of measurement errors is presented which can be used to estimate the accuracy of the measurements.|
|Richard Hopkins, Ph.D. Student
University of Surrey
Guildford, Surrey GU2 7HX,