Optimizing Periodic Intervals in Multi-Stage Waveguide Stub Bandstop Filters for Microwave Leakage Suppression
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsDear Authors,
Very nice work. I have a few recommendations for the manuscript:
- Need to define some of the lesser-known parameters, e.g. "λg". Is it "λg" or "λg"?
- Need to use an equation editor to enter all symbols, so that they are consistent throughout the manuscript. Another example, "S21" vs "S12".
- Need to have the same symbols in the text and graphs.
Best regards.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript presents a study on a waveguide bandstop filter using periodic E plane stubs to suppress electromagnetic leakage in microwave heating systems. The research is well-structured and methodologically sound, employing a systematic approach that combines electromagnetic simulation, equivalent circuit modeling, and experimental measurements, with good agreement observed among the results. The conclusions offer novel and practical design guidelines for filters. I recommend acceptance pending minor revisions.
1) The introduction could be strengthened by expanding the review of existing periodic structures (e.g., EBG, metamaterials) in waveguide filters, particularly by providing a clearer comparison with the wide-stub case studied in this work.
2) The key conclusion that the "optimal spacing is an odd multiple of λg/4" is based entirely on analysis at 10 GHz and a specific waveguide size. The generality of this design rule should be discussed—does it apply to other frequency bands or different waveguide dimensions?
3) The quality of some figures needs improvement. For example, in Figure 5(b) and Figure 9(a), legends and curves overlap, reducing readability. Enhancing contrast or adjusting layouts is recommended.
4) The conclusion should include a discussion on the limitations of the proposed design and suggest specific directions for future research.
5) The English expression should be polished in some sections where sentences are slightly wordy or awkward. Professional language editing is advised to improve clarity and fluency.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe study presents a waveguide bandstop filter (BSF) design using a finite periodic structure of short-circuited E-plane stubs to suppress microwave leakage. It achieves a stopband with transmission coefficient |S21|≤−30dB and a 4% relative bandwidth. The work explores how stub width affects bandwidth and how stub spacing influences spurious passband suppression. Simulations and experiments show that odd multiples of λg/4 spacing minimize spurious modes, and wider stubs improve stopband performance. The findings offer practical design guidelines for efficient BSFs and have potential applications in filters and antenna arrays using periodic structures. It is an interesting study and could be accepted for publication after careful revision as suggested below.
1. The introduction is lacking in highlighting the novelty. It should be rewritten citing the latest literature reports, including (https://doi.org/10.1016/j.jmst.2025.02.011) to highlight the research gap filled by this study.
2. In results and discussion, it be should be supplemented on how does stub depth variation influence the bandwidth and resonance characteristics, especially for wider stubs?
3. Please include is there a systematic optimization framework (e.g., genetic algorithms, gradient descent) that could be used to find optimal stub count and spacing for arbitrary specifications?
4. Please enrich the results by parametric sensitivity analysis: Show how variations in stub width, depth, and spacing affect performance metrics like FBW and S21.
5. Some plots (e.g., Figure 5 and 8) are dense and hard to interpret. Use color coding and zoomed-in views for critical regions.
6. In the revised manuscript it is recommended to address how the design methodology applies to other waveguide standards (e.g., WR75, WR112).
7. Supplement the revision with results for wider stubs with p = λg/2 or 5λg/4 to validate the odd-multiple hypothesis for better readability and a wide audience.
Comments on the Quality of English LanguageEnglish should be improved
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsThanks
