Review Reports

Round 1

Reviewer 1 Report

This article introduces innovative designs for dual-band substrate integrated waveguide (SIW) bandpass filters (BPFs) employing two identical open-loop ring resonators. These resonators are coupled face-to-face at the top of the SIW cavity, enabling the realization of a dual-band single-pole BPF. While the proposed filters exhibit promising characteristics, there is a lack of clarity regarding the process for selecting the circuit model parameters. Could the authors elucidate how they derived the values for the elements listed in Table 1? Additionally, it would be valuable to understand the methodology employed by the authors in crafting the architectural design. Specific details about the layout of the filter architecture are essential. For instance, what is the specified width of the gap on the substrate? Moreover, what does the parameter 'hs' represent?

 

I would also appreciate the authors' insights on the bandwidth. How can it be manipulated, and what are the inherent limitations? Concerning the second band, is it a consequence of spurious harmonics stemming from the first band? Could the authors provide some commentary on this? Is it possible to control this second band independently, or does it rely on characteristics of the first band?

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents a new design of dual-band SIW-based bandpass filters. The authors conducted a thorough literature review, presented the design and its performance in EM simulation, circuit/coupling matrix simulation, and measurement.

A comment on the structure of this paper: It’s better to put the literature review/related work into a separate section rather than squeezing in the Introduction Section. In Introduction, could you summarize the pros and cons of the previous designs to highlight the contributions of your new design?

The quality of English language is fine. Please check for typos before publishing.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Overall, your review is quite clear, but there are some areas where improvement can be made. Here are my suggested revisions:

Several points need clarification. Firstly, it is important to explain the reasoning behind the choice of frequency. How is the metric for the proposed filter determined based on specific user scenarios?

 

Secondly, the most crucial aspect is the detailed explanation of the filter construction in Section 2. It would be beneficial to include a simulation demonstrating the field strength before and after the introduction of the OLRRs. Additionally, the selection process for the dimensions of the OLRRs, particularly the York part where two OLRRs are placed face to face, should be elaborated upon. What is the reason behind the introduction of another frequency?

Regarding Figure 7, although the coupling coefficient appears to be small, it would be helpful to specify the optimized coupling coefficient and the realizable coefficient considering physical limitations.

When showcasing the setup photo, it would be interesting to include an image of the back side of the board to provide readers with an idea of the ground plane's size.

To further illustrate the coupling between two elements, it would be valuable to provide a more comprehensive one-cell and two-pole comparison.

Finally, it would be worth exploring the loss mechanism in more depth. What type of loss is it? Is it related to metallic ohmic loss, loss in the dielectric, or something else? Can it be mitigated, for example, by increasing the height of the PCB?

Overall, the paper is clear and encompasses both simulation and measurement aspects. However, the author can refine the language to enhance its quality

Author Response

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Author Response File: Author Response.pdf