Guided-Wave Properties of Slow-Wave Substrate-Integrated Waveguide Patterned with Non-Uniform Metasurface Unit Cells with Various Degrees of Rotation

Round 1

Reviewer 1 Report

A rich work on non-uniform metasurafes for the purpose of  metasurfaces to control the cutoff frequency and phase constant of an anisotropic SW-SIW. I found the paper interesting and useful and the structure of the paper is acceptable overall. The simulated and measured results also make sense; however, there are some serious aspects that need improvements and some ambiguities that need to be rectified. Here are the detailed comments:

I think there are too many formulas in the paper. Many of them are kind of general equations that can be easily referred to.

The novelty is not clear throughout the paper as well. Please clearly mention the novelty of the paper in the Abstract and preferably re-iterate at the end of your introduction.

Please explain in detail the boundary condition used in Fig. 1

The introduction needs improvement as it seems to be abrupt and does not cover the latest metasurface-related achievements, specially in terms of their applications. It should be mentioned that metasurfaces can be used for gain enhancement as explained in: Gain enhancement of wideband circularly polarized uwb antenna using fss. Metasurfaces are also used to design multifunctional components, such as filter/antenna-sensor as explained in: tunable terahertz filter/antenna-sensor using graphene-based metamaterials. Transmit array is another critical application of metasurfaces as explained in: all-metal wideband metasurface for near-field transformation of medium-to-high gain electromagnetic sources. Metasurfaces also are used as spatial filters, as demonstrated in Single-layer ultra-wide stop-band frequency selective surface using interconnected square rings. Artificial intelligence-based metasurfaces are a new class of metasurfaces with various applications especially for environmental sensing as explained in: advancements and artificial intelligence approaches in antennas for environmental sensing. Using graphene-based structures is another new approach for designing metasurfaces that can bring reconfigurability to electromagnetic devices as explained in: recent and emerging applications of Graphene-based metamaterials in electromagnetics.

Please add electric field distribution and current distribution at some particular angles.

I cannot see any comments on the fabrication cost.

Measured and simulated results [Fig 10]: There are some discrepancies in this fig between the measurement and simulations. While they are not fully justified. Additionally, please explain how those errors can be minimized in the design and fabrication process. 

There is no comment about the prototyping (different fabrication types) of metasurfaces. It should be mentioned that metasurfaces can be made of all-metal units and add relevant refs. Here is one recommended ref for this purpose:

 All-metal wideband frequency-selective surface bandpass filter for TE and TM polarizations. Transactions on Antenna and Propagation, 2022, DOI: 10.1109/TAP.2021.3138256 

 

Author Response

Dear editor,

We would like to thank the associate editor and the reviewers for their time and precious comments which greatly helped to improve the quality of our manuscript.Please see the attachment.

Sincerely yours

Hailu Jin

 

Author Response File: Author Response.docx

Reviewer 2 Report

The proposed slow wave SIW structure is novel for sure, as compared with previous designs. The design procedure and well agreed results are also presented.

1. Pictures 1 and 5 are not clear enough, please handle them clearly.

2. Generally there is a tradeoff between the circuit size and loss. But the implemented circuit loss is 2 dB around 10 GHz, which is a little large. Please comment this and explain why the loss is large.

3. Does the pattterned metal shape has radiation loss. The general top metal layer of the SIW is complete. Please comment the pracical application value of this structure.

 

Author Response

Dear editor,

We would like to thank the associate editor and the reviewers for their time and precious comments which greatly helped to improve the quality of our manuscript.Please see the attachment.

 

Sincerely yours

Hailu Jin

Author Response File: Author Response.docx

Reviewer 3 Report

In this paper, a novel slow-wave substrate integrated waveguide structure is proposed. By loading non-uniform metasurface elements periodically, the equivalent permittivity and magnetic permeability can be adjustable, which provides a new idea for SIW transmission lines with different cutoff frequencies and propagation constants. The results are interesting. I have following questions:

1) The quality of pictures such as Figure 1 (b), Figure 5 is not clear enough, please give a clear version, in addition, the illustration in Figure 8 and Figure 10 is too complex to affect reading, please give a more concise version;

2) With the surface-etching process, lower cut-off frequency and slower phase speed are introduced, but what are the disadvantages of doing so? To what extent does it cause insertion loss? Please indicate it in Figure 10;

3) Page 12, line 328, icon name is missing, please modify.

4) In conclusion, it is necessary to elaborate more on the possible value of the meaning of the design to the industry.

Author Response

Dear editor,

We would like to thank the associate editor and the reviewers for their time and precious comments which greatly helped to improve the quality of our manuscript.Please see the attachment.

Sincerely yours

Hailu Jin

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

The paper has been improved and ready for publication

Author Response

Dear editor,

We would like to thank the associate editor and the reviewers for their time and precious comments which greatly helped to improve the quality of our manuscript.Please see the attachment.

Author Response File: Author Response.docx