Design and Analysis of Polarization-Independent, Wide-Angle, Broadband Metasurface Absorber Using Resistor-Loaded Split-Ring Resonators

Round 1

Reviewer 1 Report

Dear Authors,

Thank you for writing this paper. I have a few major questions/comments (please see below) which I hope will help improve the quality of the manuscript.

1. I do not have access to the full paper, but have you looked at this paper: https://link.springer.com/article/10.1007/s11664-016-4693-0? I did not find this paper cited, but it looks like the work was similar/very relevant to the work presented here. Could you help me understand how your design improves upon that research or the work in reference [23] that you cite?

2. Please check the quality of English throughout, it needs a lot of attention.

3. In line 27 of abstract, could you clarify “more efficiently” with respect to what?

4. Since there is a copper plate covering the top of the bottom dielectric FR-4 substrate, I was wondering what role does this dielectric play and is it even required?

5. Could you elaborate what you mean by “wasted” in page 6, line 168?

6. Could you explain how the air layer causes Q to decrease as mentioned in page 9 lines 196/197?

7. When you say that “direction of EM wave is unknown” in page 9 line 223, it would be good to give some context for the possible applications of this technology.

8. In page 9 line 225, please clarify/quantify “good incident angle”.

9. Have you measured the prototype at different incident angles and both TE/TM?

Thank you

Author Response

Dear Reviewer 

Thank you so much for taking time to review our paper.

"Please see the attachment"

Author Response File: Author Response.pdf

Reviewer 2 Report

Electromagnetic absorbers play an important role in the development of modern types of radio equipment. The use of metamaterials for their manufacture is a modern trend in this field of technology. In this regard, I believe the topic of the work submitted for review is relevant.

1. The first section provides a fairly detailed literature review, research problem and its solution. Literary sources are quite modern (almost half of them came out in the last five years).

2. The second section presents the design of the absorber with the main characteristics.

3. The third section presents the results, which are well presented and described in detail. The simulation results are verified experimentally (Section 4), which significantly increases the value of the data presented in the article.

The results are discussed together with the results.

4. The fourth section presents the results of an experimental verification of the characteristics of the developed absorber. This section also compares the new results obtained with known literature data.

5. The conclusions are based on the obtained new results.

The work is well written and framed. I believe that it can be accepted for publication in its current form.

Author Response

Dear reviewer 

Thank you so much for taking time to review our paper.

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

In this paper a broadband meta-surface (MS) absorber is designed and implemented, based on square split ring resonators (SSRRs) and loaded with lumped resistors. This paper can be reconsidered after major revision listed as follows:

1-Why  2.09 GHz, 4.34 GHz, and 6.2 GHz frequencies are choose to evaluate absorber's performance using E-field and surface current distribution in Figs 4 and 5. Add sufficient explanations.

2- In order to compare the performance of the proposed MS absorber with other absorbers reported in Table 1,  the thickness per (λmax- λmin) and the unit cell size per λ²max (where λ is the wavelength in free space) should be provided in Table 1. Like ref [24]. It seems that the proposed absorber has a large size, which should be fairly discussed. 

3- The geometry dimension parameters are given in lines 106-108, and in Figure 1(a) and (c) geometry of proposed absorber are depicted. In these figures there are R1, R2, R3 and R4, but in the text there is only one value R=560. Correct this issue.

4- In fig 10b measurement setup figure, has a low quality, improve the quality of this figure and if it is possible add real photo of the measurement setup including device under test, applied vector network analyzer (VNA) and two horn antennas.

5- There are some typos and grammatical mistakes. Read the text carefully for example:

-line 249  size  280 ? 280 mm²

6- There is large difference between measurement and simulation results at 1GHz and 7 GHz, in Fig 10 in some frequencies more than 50%. Provide sufficient explanation about these differences.  

Author Response

Dear reviewer 

Thank you so much for taking time to review our paper.

"Please see the attachment"

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for the detailed responses and for considering my suggestions. One point that was not clear to me regarding the measurement shown: were you able to measure both TE and TM?

Thank you

Author Response

Dear reviewer

Thank you so much for taking time out of your schedule to review the paper.

"Please see the attachment"

Author Response File: Author Response.pdf

Reviewer 3 Report

The authors have been answered all of my comments this paper can be accepted in present form

Author Response

Dear reviewer

Thank you so much for taking time out of your schedule to review our paper.

I would like to inform you, the paper checked again by the native English speaker

Thank you again