Design of Laminated Waveguide Microwave Passive Components using Multilayer LTCC Technology
Date Issued
2012
Date
2012
Author(s)
Shen, Tze-Min
Abstract
This dissertation focuses on the development of laminated waveguide passive components including millimeter-wave filters and multi-function 180° hybrids in multilayer low-temperature co-fired ceramic technology. In the beginning, laminated waveguide bandpass filters with third-order Chebyshev and trisection responses are developed for V- and E-band applications. Cavity resonators are stacked in 3-D space to reduce circuit areas and increase vertical coupling mechanisms. The transmission zero of the trisection filter can be located at either side of the passband, depending on the resonant mode of the cavity on the main coupling path. Besides, a Ka-band waveguide diplexer is also presented with a fourth-order quasi-elliptic response at each band, resulting in good selectivity between the adjacent channels.
Next, a broadband planar laminated waveguide magic-T is proposed. Two orthogonal slots are used to excite even- and odd-symmetric field patterns in the main waveguide, respectively, resulting in a good isolation between each other. The equivalent circuit model is established and the input admittance is estimated to facilitate the structure design for wideband performance. The highly symmetric physical structure provides a broad bandwidth of low imbalance in phase and magnitude, with isolation between sum and difference ports greater than 40dB in the full operation band.
Finally, laminated waveguide magic-Ts with imbedded bandpass filter responses are developed for single and dual-band applications. In the single band design, the cavity with degenerate, but orthogonal resonant modes, i.e. TE102 and TE201 modes, is utilized to provide the in-phase and out-of-phase responses of the magic-T. On the other hand, the dual-band magic-T design exploits two kinds of overmoded cavities to achieve the sum and difference functions, respectively. The operated frequency bands are controlled by adequately choosing geometric shape of laminated waveguide cavity resonators. The filter responses are synthesized by cascading the cavities with proper coupling strengths according to the filter specification. Two design examples of the magic-Ts with a single-band third-order Chebyshev response and a dual-band second- order Chebyshev response are given to verify the proposed concepts.
Subjects
Ceramics
filter
laminated waveguide
magic-T
multilayer
Type
thesis
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