Manufacturing Error Effect Suppression of Laminated Waveguide Filters Using Overmoded Cavities with Miniaturized Design
Date Issued
2015
Date
2015
Author(s)
Kuo, Ming-Hsuan
Abstract
The characteristics and applications of overmoded laminated waveguide cavities are investigated in this thesis. Laminated waveguide filters using either fundamental mode or overmoded cavities are firstly designed at millimeter frequencies in low temperature co-fired ceramic (LTCC) substrates. The performance variations of different filter designs due to manufacturing error are then examined by simulation. Finally, folded overmoded cavities are proposed to accomplish a miniaturized design of a dual-mode 4th order filter. In order to analyze the performance variation due to manufacturing error, two different filter groups with the same specification but different cavity modes are designed in this thesis. The performance of these filters are then examined with respect to different kinds of manufacturing error, inclusive of layer to layer alignment error, metal printing error, and metal thickness error. The analysis showed that the performance variation due to manufacturing error can be more effectively suppressed for filter designs using overmoded cavities, compared to those using fundamental mode cavities. Especially for the layer to layer alignment error, filters using TE101 suffer great distortion with return loss at center frequency is 5dB while TE301 remains above 15dB. Advanced applications of overmoded cavities at millimeter-wave frequency bands are also proposed in this thesis. A miniaturized design is accomplished by double- folded overmoded cavities in dual-mode filter configuration. By changing the boundary condition of double-folded overmoded cavities to adjust the ratio of resonant frequencies, vertically stacking the proposed novel cavities with proper slot positions to realize the external quality factors and coupling coefficients with respect to different modes, a miniaturized overmoded cavity filter can be accomplished. Due to the absence of neighboring modes, the proposed filter has excellent out-band performance with insertion loss less than 30dB and the circuit size reduced to 72.7% of double folded filter using fundamental mode and 54% of original 4th order filter with unfolded cavities.
Subjects
laminated waveguide
low-temperature co-fired ceramic
multi-mode
filter
manufacturing error
double-folded cavity
Type
thesis
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