Design of 60GHz Dual-Mode Bandpass Filters using Substrate Integrated Waveguide
Date Issued
2008
Date
2008
Author(s)
Liao, Ming-Wen
Abstract
This thesis proposes two types of 60 GHz bandpass filters based on dual-mode existing in substrate integrated waveguide realized in multilayer technique. The structure of substrate integrated waveguide has two arrays of via-holes as the side walls of a conventional rectangular waveguide. Hence, using this structure, one can integrate with other active or passive planar circuits easily. However, this kind of waveguide can only exist TEmnp (n=0) mode. First type of bandpass filter is designed by cascading two cavities existing with dual-mode to give a transmission zero at each side of pass-band. The feeding circuit is a microstrip line because of the field in microstrip line is close to that in cavity. The lowest︱S21︳is -1.15 dB, the highest︱S11︳is -12.6 dB and bandwidth is 5.65%. Then two cavities are stacked by two layers of RO5880 to reduce the circuit area. However, because the locations of input and output ports are on the different layers, a transition is designed for easy measurement. The lowest︱S21︳is -3.32 dB, the highest︱S11︳is -17.2 dB and bandwidth is 4.63%. Another type of filter is designed based on single cavity implemented on two layers of RO5880 with a microstrip line to excite the resonator through a coupling slot etched at the top metal layer of the cavity. The second transmission zero is introduced through the coupling path at top layer between the input and output ports. The lowest︱S21︳is -2.66 dB, the highest︱S11︳is -4.45 dB and bandwidth is 4.13%. These three filters are designed in V-band and fabricated on single or two layer RO5880 substrate. Measurement results are shown in a good agreement with the simulation results.
Subjects
SIW
bandpass filter
dual-mode cavity
Type
thesis
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