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Jeffrey S. Fu Md. Nurunnabi Mollah Nemai C. Karmakar 《International Journal of Infrared and Millimeter Waves》2006,27(4):571-589
A microstrip transmission line on a Chebyshev distributed chirped I-D photonic bandgap structure (PBGS) is proposed. Two different approaches are utilized to realize Chirped
PBGS. Firstly, the inter-element distance of PBG elements is chirped with conventional chirping technique. Secondly, using
Chebyshev distribution varies the inter-element distance. For both the cases, the amplitude is made non-uniform by varying the amplitudes
in accordance with the co-efficient of Chebyshev distribution. It can be seen that the conventionally chirped PBGS having Chebyshev distribution in amplitude improves the over all performance. The inclusion of Chebyshev distribution in period calculation further improves the performance. It can be seen that the Chirped and non-uniform PBGS
generates excellent bandgap performances in lower valued height of substrate that are superior to the performances available
in the open literature. 相似文献
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S. K. Datta Lalit Kumar B. N. Basu 《International Journal of Infrared and Millimeter Waves》2008,29(11):1048-1059
A simple closed form formula for the estimation of π-mode stopband in an azimuthally asymmetric helical slow-wave structure (SWS) was developed following coupled-mode analysis
of multiple reflections of the degenerate space-harmonic modes from the support rod discontinuities. The method incorporates
the effects of circuit loss, and accrues the accuracy of 3D electromagnetic analysis by allowing the use of dispersion characteristics
obtainable from any standard electromagnetic modeling. The formula is simple and amenable to easy computation, even using
a scientific calculator, and without resorting to exhaustive and time-intensive numerical computation, and at the same time,
without sacrificing the accuracy in results. The analysis was benchmarked against published results and excellent agreement
observed. The analysis was further used for demonstrating the stopband phenomenon for a typical millimeter-wave helical slow-wave
structure. Compared to low frequency structures, the stopband phenomenon for a millimeter-wave structure was found to be more
pronounced, and an interesting inference was drawn as to how asymmetry induced stopband might be made to advantage in combating
π-mode instabilities in a millimeter-wave traveling-wave tube. 相似文献
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