研究目的
To present two substrate-integrated waveguide (SIW) filtering crossovers with high selectivity, employing orthogonal degenerate TE201 and TE102 modes for cross transmission and channel isolation, and to improve the selectivity and reduce the footprint of the crossovers.
研究成果
Two advanced third-order SIW filtering crossovers, including a miniaturized one with improved upper-band selectivity and a highly selective one with one TZ on each side of the passband, have been presented. Miniaturization is realized by employing the TE101-mode rectangular cavities instead of oversized square cavities. TZs, whose positions are controlled by adjusting the relatively offset positions of the I/O ports, have been introduced in the SIW filtering crossovers and satisfactory results have been achieved for both designs.
研究不足
The realizable bandwidth and the isolation contradict each other and are both limited to the coupling window width wc. As the wc gets larger, the bandwidth becomes wider, but the energy of the degenerate mode in another channel becomes stronger, thus the isolation level gets worse.
1：Experimental Design and Method Selection:
The study employs orthogonal degenerate TE201 and TE102 modes in a center square cavity for cross transmission and channel isolation. Offset coupling positions are exploited for surrounding TE101-mode rectangular cavities to produce transmission zeros (TZs) above the passband in the first crossover design, and for TE201-mode oversized rectangular cavities to generate one TZ on each side of the passband in the second crossover design.
2：Sample Selection and Data Sources:
Two prototypes centered at 20 GHz are designed, fabricated, and tested.
3：List of Experimental Equipment and Materials:
The demonstrations are designed and fabricated on
4：508-mm-thick Rogers RT/Druid 5880 substrates with relative dielectric constant εr = 2 and loss tangent tanδ = Experimental Procedures and Operational Workflow:
The initial sizes are calculated using specific equations for cavities 1-4 and the square cavity 5, with dimensions figured out accordingly. Design curves are extracted to realize the required external quality factor Qe and coupling coefficient Mij.
5：Data Analysis Methods:
The frequency responses are analyzed to observe the generation of TZs and the performance of the crossovers.
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