Ku-band substrate integrated waveguide bandpass filter design using mechanical tuning
Author(s)
Advisor
Date
2019-02Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Substrate integrated waveguide (SIW) filters are widely used due to their easy
fabrication techniques and relatively high quality factor. In microwave frequencies,
manufacturing tolerances become comparable with wavelength and affect
filter performance. Tuning resonator center frequencies and couplings between
resonators allow correcting the errors that are caused by imperfections. An iris
bandpass filter is designed in Ku-band using coupling matrix approach which relates
mathematical coupling values to physical dimensions. SIW tuning is usually
done by adding varactors to the circuit. This introduces nonlinearities which may
be undesirable while also requiring external control voltages. A mechanical tuning
method for SIW, similar to tuning screws that are used in waveguide filters,
is analyzed for resonators and couplings. It is modified by using small surface
mount resistors to achieve a more compact structure. Tuning mechanisms are
inserted to designed filter and fabricated on a low loss substrate. Time domain
method for tuning coupled filters is introduced as a tuning algorithm. Using
mechanical tuners, SIW filter is tuned to desired filter performance.