| Research Abstract |
The power-leakage effect and its related phenomena must cause significant distortion to ultrawide-band or ultrashort pulses propagating on planar-circuit lines. This is our standpoint in this research, and, to attack this problem, we set two subjects running in parallel.
The first subject is related to the investigation on the eigen-solution behaviors, because the existence of some unusual dispersion behaviors for leaky solutions yields a new type of ultrashort-pulse distortion. Actully, we discovered, at the early stage of this research, that there can exist a frequency range within which the bound and leaky modes can propagate simultaneously. Soon after this discovery, it was also shown by us that this simultaneous propagation effect is actually quite general, rather than being unique or rare, and is very important in connection with the ultrashort-pulse distortion. Actually, we were successful in explaining the unique distortion in the pulse tail by the knowledge of both this simulta
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neous-propagation effect and the nonlinearity of the dispersion curves. It was continued further to investigate the dispersion behavior of leaky mode at high frequencies, where there should be several types of leaky mode. Then, at the final stage of this research, we also discovered that there can exist a frequency range or a new spectral gap witin which no leaky modes can propagate. A concise study of the effect of this new spectral gap on the pulse distortion was included in this research report.
The second subject is to investigate the effect of dimensional structures of transmission lines on the pulse distortion. In this research, a special care is paid on the effect of a metal box packaging planar circuits, because the ultrashort-pulse distortion occurs due to delayd echo pulses produced by the multiple reflection of the leakage fields of the main pulse at box surfaces. Actually, it was successfully concluded that the effect of such echo pulses is serious on the pulse distortion propagating on practical planar transmission lines. Less
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