Advantages of Plate Antennas over Loop Antennas for Circular Polarization—Its Application in Array Antenna with a Simplified Feed
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper presents a parametric study on factors affecting the axial ratio bandwidth of CP antennas using MoM. This systematic study is valuable for understanding techniques to enhance axial ratio bandwidth. Below are some suggestions for improving the paper:
1. The word "relationship" in the title may not be appropriate, as the paper focuses on demonstrating the advantages of the plate antenna over the loop antenna rather than exploring their relationship.
2. Line 62: "The side length and corner truncation (L, delta_l) are selected for CP radiation [13]." Line 67: "At each value of H, the element parameters (L, delta_l) are optimized for CP radiation."
--> Please clarify the definition of "CP radiation." For instance, the state that the AR close to 0 dB at f_0, etc.
3. It is recommended to include the VSWR of the antenna without the cranked feed in Fig. 8.. This will help verify that the antenna with the cranked feed achieves better impedance matching bandwidth.
4. In Table 1, it is suggested to express the antenna height in terms of wavelength to provide fairness in comparison.
Comments on the Quality of English Language
Minor editing of English language required.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors have presented an interesting relationship between CP loop and plate antennas along with array example in simulation as well as in experiments. Some of the observations are as follows,
1. The paper is written in a report writing style instead of manuscript style. Especially, the introduction section needs to be rewritten with technically known terms and verbs.
2. The paper structuring is also confusion. It is suggested to make fewer paragraphs with clear content division.
3. Page 2, Line 58, the coded software is mentioned. It would be better to explain it a little bit for the understanding and reproduction of the results.
4, Page 6, Line, 150, the CST should be mention in details such as CST Microwave Studio 2024.
5. Some of the references need to be updated e.g., Ref 2,3,5,6,7,8,10,11,13,16. They are either old or self-cited without clear relevance.
Comments on the Quality of English LanguageThe Quality of English comprehension could be improved. For example, "This is because CP antennas have unique characteristics (e.g., 22 reducing a multipath interference and polarization mismatching), which are helpful in 23 many applications, such as mobile, navigation, and satellite communications [2, 3]." In this sentence, there is not need to start with "this is because". Please try to correct similar mistakes.
The paragraph 3 of Introduction needs to be rewritten, and restate "Motivation for this paper comes from the abovementioned facts".
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsAuthors present a study of the operation and characteristics of circularly polarized loop and plate antennas. Authors present the structure, design, performance, and experimental verification of the said antenna structures. The manuscript is well-written to the point in a succinct way. This review finds that there are not much to be revised.
My comments are as follows.
1. Principles of CP operation.
Please add principles of the circular polarization with structures of Figure 1 and 4. [13] does not include the principles of operation either.
2. VSWR bandwidth vs AR bandwidth
Figures 2 and 5 show AR bandwidth vs H ranging from 0.1 wavelength to 0.25 wavelength. Figure 8 shows that the VSWR bandwidth is large enough to include the AR bandwidth with H = 0.25 wavelength. Please add some results and comments on the VSWR bandwidth when H < 0.25 wavelength since an antenna needs to satisfy the VSWR bandwidth as well as the AR bandwidth.
3. Quasi-two source antenna of Figure 4:
A 90-degree phasing between two orthogonal currents is obtained by using L = 0.25 wavelength. The amplitude balance is realized by simple branching of the feed wire. The branching structure is asymmetric and it is not sure that the 1:1 balanced amplitude division. Please check current amplitudes and add some comments.
4. Figure 8:
A crank line is used to obtain impedance matching. Please explain the principles of impedance matching. Is the crank line a quarter-wave transformer? Please include the input impedance of Figure 1(b) structure and the characteristic impedance of the crank line.
5. Figure 10:
Two antenna elements is fed by a coaxial cable and a power divider. Please explain the principles of the impedance matching. Include the input impedance of a single element and the characteristic impedance of the horizontal line T1-T2.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe detailed comments are listed as follows:
1. This paper does not explain the relevant principles, such as the reason why the axial ratio bandwidth of the loop antenna and plate antenna changes with the antenna height. Analyze appropriately.
2. The relevant parameters of the designed antenna are not given in detail, which makes it difficult to reproduce this article.
3. Please explain why a 75 Ω coaxial feed line is used.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe revised manuscript is acceptable for publication
Reviewer 4 Report
Comments and Suggestions for AuthorsI have no further comments.
