Design And Optimization Of Transition For Air-Filled Substrate Integrated Waveguide
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Date
2018-04-01
Authors
Mansor, Nur Hidayah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Air-filled substrate integrated waveguide (SIW) is a new form of transmission lines
that have been used as interconnect with conventional SIW circuits to reduce losses
in the circuits. For an effective interconnection, various proposals for the transition
between the air-filled and dielectric-filled media in SIW have been given. To
increase the performance of the transition, the insertion and return losses along the
transition must be minimized. However, the losses in the transition are not well
understood. This is because the propagation of electromagnetic waves along the
inhomogeneous media with varying geometry is difficult to characterize with respect
to losses. This thesis presents an in-depth study to characterize the propagation of the
waves and losses in the transition using full-wave analysis. From the assessment of
the transition geometry from air-filled to dielectric-filled SIW, an optimization
procedure is developed to further minimize the losses in the structure. Defining the
shape of the transition taper with the cubic clamped spline function, the developed
procedure shows that further reduction of losses is possible within the prescribed
frequency bands, i.e., Ka-band (26-40 GHz) and U-band (40-60 GHz). Furthermore,
the length of the transition taper can also be significantly reduced while maintaining
an optimal quality of signal transmission in the transition. Hence, by optimizing the
transition geometry, the signal in the form of electromagnetic waves will pass
through the transition with minimal return loss and insertion loss. The numerical
studies in specific cases of the transition optimization show an improvement of 45%
return loss at Ka-band frequencies and 48.3% return loss at U-band frequencies.
Meanwhile, the improvements of transmission loss by 3.1% at Ka-band and 4.0% at
U-band were obtained. The findings of the present study will contribute to the
development of a more compact design of coplanar circuits for any frequency bands
with better performance.