Abstract:
Waveguide filters are vital components in wireless communication and radar systems.
These filters are used to pass and attenuate desirable signals from microwave systems. They
have very high Q and capable of handling high power but the size, weight and cost are the main
issue as the components sizes continues to decrease. An alternative is the substrate integrated
waveguide technology, which has recently been proposed. SIW is a waveguide within a
substrate, consisting of two sets of rows of metallic via holes in a substrate. They are low cost,
light weight and compact as compared to metallic waveguides as they can be developed using
printed circuit board (PCB) fabrication.
This thesis work is based on the design and development of SIW filter at X and Ku
band. An important step in the design of these filters involves determining the width of the iris
as a function of coupling factor. This was accomplished using the EM simulation based
software HFSS, with the help of which a design curve (iris width vs. coupling) was generated
and used in the design of the two filters. The two 5 poles Chebyshev bandpass filters have been
fabricated and measured using low cost PCB process on Rogers 4003. The measured results at
10GHz presents 380MHz bandwidth, 6.6dB insertion loss and return loss better than 12.5dB,
whereas the measured results at 16GHz presents 410MHz bandwidth, 8.1dB insertion loss and
return loss better than 13dB. The excess passband insertion loss is due to the conductor losses
and lossy nature of the substrate. Measured results are in good agreement with the simulated
results validates the accurate design curves.
