A Dual-Band Quarter-Wave Transform and Its Applications to Directional Coupler Design
Bibliographic record
Abstract
The quarter-wave transformer is a useful circuit for impedance matching. In this paper, we use three equal-length transmission lines to design dual-band quarter-wave transformers. Closed-form design equations are derived. The proposed structure is found to be suitable for dual-band operation with a frequency ratio greater than 5. Numerous microwave passive components are composed of quarter-wave transformers. For these components consisting of quarter-wave transformers, the use of dual-band quarter-wave transformers can inherently result in dual-band operation. The proposed structure is, therefore, a simple and effective element for designing dual-band microwave passive components with a frequency ratio greater than 5. Because the existing techniques for designing dual-band circuits are mostly suitable for frequency ratios lower than 5, the proposed structure, therefore, complements the existing techniques. To demonstrate the applicability of the structure, two directional couplers, namely, a dual-band branch-line hybrid and a dual-band rat-race hybrid, are designed and fabricated on a RO4003C substrate. Measurement results validate the applicability of the proposed structure.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".