Designs and Challenges in Fluid Antenna System Hardware

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Before the manuscript is published, the authors should respond to the following comments.

1- The author should arrange the keywords alphabetically.

2- The authors should include a paragraph at the conclusion of the introduction that describes the structure of the proposed article.

3- The authors should specify in the text that what are the fields where fluid antennas do not work and why.

4- The term "fluid antenna system" is bogus. Fluid antenna is sufficient. Readers will easily grasp that they are systems.

5- The author’s claim "Traditional designs focus on optimizing radiation characteristics like operating frequency, polarization, and radiation pattern, but lack the ability to reposition the radiators themselves. This is because antenna experts typically evaluate antenna performance based on established metrics such as S11, radiation pattern, gain, and efficiency, and seldom consider the advantages of position agility. However, wireless communication is about more than just antenna efficiency. The precise location of signal reception is more crucial" is false. Please take it off. An antenna's performance, after which you can modify each one to suit your needs. Antenna engineering and signal processing are completely distinct fields. Talking on the antenna as a system causes the first one to malfunction.

6- Why do you bring up Figure 2, which depicts the radiation pattern, if the antenna characteristics are irrelevant to the research that is being presented? All antenna characteristics, including as gain, beamwidth angle, polarization, field distribution, transmitted power, and so forth, are included in the radiation pattern.

7- The authors should address the influence of fluid material on antenna characteristics like as gain, circular polarization, impedance bandwidth, return loss, and beamwidth angle.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The presented review paper is devoted to the issues related to research work conducted on antennas based on the FAS technique. A simple description of the principles of operation and applications of antennas constructed in the LM-FAS, MMA-FAS, PRA-FAS and M-FAS formats is made. The key areas of research on the analyzed group of antennas are also briefly characterized. The article is written in an accessible way, using a fairly simple specialist language, which will certainly increase the number of readers. In order to improve the quality of the paper, it is recommended to introduce several corrections and extensions:

a) The abstract should be restructured so that the vast majority of the content is a description of the results of the analyses conducted, not an introduction to issues related to FAS.

b) It is absolutely necessary to make a tabular summary of the analyzed antenna technologies from the FAS family, along with a distinction of specific parameters and their ranges proposed or tested by individual research teams. References to cited papers must also be listed here. The number of literature items must be increased. The table must also include bullet points of the expected applications of antennas in various fields, not only telecommunications.

c) The paper must contain significantly more diagrams or photos of the analyzed structures, so that the reader can familiarize themselves directly with the system geometry of the components of antenna devices.

d) The subject of the feeder coupling of antennas with signal sources must be much more extensive, as this will also determine their use in small-sized devices. The frequency ranges of the antennas are key here.

e) The topic of transparent antennas, also in the FAS design, must be significantly expanded, because such systems will be used in 6G systems, also in RIS applications. I propose devoting a separate subchapter to this, analyzing which structures and which materials are currently being tested. It should be noted that transparent antennas are already being manufactured.

f) The chapter on discussion must be significantly expanded. Creating a comprehensive table with a list of parameters and technologies will certainly be helpful in this regard - point b).

g) Other minor comments:

1. Fig. 2: the caption under the figure must contain precise descriptions of figures a) and b), i.e. what they are characterized by. Currently, the description of figures a) and b) is only in the text of the paper and is very general.
2. Line 264: the reference number is missing from the sentence.
3. Fig. 5: the figure requires a more precise description of the variables placed, with specific values ​​given on the figure itself or in the caption under the figure.
4. Page 9: you must decide whether the headings of subitems concerning key research areas are bold or not.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Unfortunately, the reviewer's comments were almost completely ignored. I propose, however, to adapt the comments in the next version of the paper, at least in part. Otherwise, the paper will be too modest for a review article and will have to be rejected. The reader of a review article cannot be constantly referred to other scientific articles, because he will be discouraged by the inconsistent material.

Author Response

We have no futher revision.