A Fixed-Frequency Beam-Scanning Leaky-Wave Antenna with Circular Polarization for mmWave Application
Round 1
Reviewer 1 Report (Previous Reviewer 1)
Comments and Suggestions for Authors
Authors have solved my concerns. Thank you.
Author Response
Dear reviewer,
We would like to thank you for the helpful comments and suggestions. The manuscript (ID: photonics-3520938) has been revised carefully according to the comments and suggestions. We hope that the revisions can meet the requirement of this publication.
The following are the responses to the comments.
Comments and Suggestions for Authors:
Authors have solved my concerns. Thank you.
Response:
Thank you very much for all your suggestions and comments!
Reviewer 2 Report (Previous Reviewer 2)
Comments and Suggestions for Authors
The comments have been addressed well.
Author Response
Dear reviewer,
We would like to thank you for the helpful comments and suggestions. The manuscript (ID: photonics-3520938) has been revised carefully according to the comments and suggestions. We hope that the revisions can meet the requirement of this publication.
The following are the responses to the comments.
Comments and Suggestions for Authors:
The comments have been addressed well.
Response:
Thank you very much for all your suggestions and comments!
Author Response File: 
Author Response.pdf
Reviewer 3 Report (Previous Reviewer 3)
Comments and Suggestions for Authors
The authors have addressed the reviewers' concerns and made the necessary revisions, including clarifying the antenna structure, enhancing the discussion on OSB suppression, and providing additional experimental validation. The revised is now technically sound. However, in Figs. 8(a) and (b), while the simulation and measurement results show good agreement in gain, there is a noticeable discrepancy in beamwidth, particularly at 30 GHz. Could the authors clarify the reason? Overall, I recommend acceptance.
Comments on the Quality of English Language
Can be improved
Author Response
Dear reviewer,
We would like to thank you for the helpful comments and suggestions. The manuscript (ID: photonics-3520938) has been revised carefully according to the comments and suggestions. Blue highlighted text is used to show where changes have been made in the manuscript. We hope that the revisions can meet the requirement of this publication.
The following are the responses to the comments.
Comments and Suggestions for Authors:
The authors have addressed the reviewers' concerns and made the necessary revisions, including clarifying the antenna structure, enhancing the discussion on OSB suppression, and providing additional experimental validation. The revised is now technically sound. However, in Figs. 8(a) and (b), while the simulation and measurement results show good agreement in gain, there is a noticeable discrepancy in beamwidth, particularly at 30 GHz. Could the authors clarify the reason? Overall, I recommend acceptance.
Response:
Thank you for pointing this out.
For a leaky-wave antenna, the propagation constant:k0 = β + jα is an important parameter for the radiation properties, whose real part, phase constant β controls the main-beam direction, and the imaginary part, attenuation constant α decides the beamwidth. On one hand, the machining tolerance is easy to lead a deviation on the practical antenna aperture when the unit is a circular split-ring-shaped patch in the fabrication; on the other hand, the RLC circuits is used to replace the PIN diodes in the simulation, but in fact, coupling slots cannot be completely closed using diodes, and hence there are not ideal distribution of “0” and “1,” causing difference between the realized attenuation constant and the theoretical ones. Besides, the coupling between the adjacent elements will also have effect on the attenuation constant. Thus, the realized attenuation constant has difference with the the simulated result, which leads to a discrepancy in beamwidth.
Thank you very much for all your suggestions and comments!
Author Response File: Author Response.pdf
Reviewer 4 Report (New Reviewer)
Comments and Suggestions for Authors
This paper propose a periodic reconfigurable leaky wave antenna based on Slot Waveguide (GGW), which combines fixed frequency beam scanning (FFBS) and circular polarization characteristics to achieve high gain and wide scanning range in the millimeter wave frequency band, which has certain technical novelty.
(1) The table comparing with existing work (Table 2) clearly demonstrates the performance benefits, but needs to be supplemented by an in-depth discussion of the limitations of the existing art.
(2) The consistency verification between the simulation and the measured results is sufficient, but some key data (such as the difference of S-parameters and the measured value of radiation efficiency) are not displayed in detail, so it is recommended to supplement specific numerical values or error analysis.
(3) If the design details of the PIN diode control circuit (such as bias network layout, power consumption, and switching speed) are not well described, it is recommended to supplement the relevant circuit diagram or parameter description.
(4) Some syntax errors need to be fixed (e.g. "dependently controlled" should be "independently controlled").
(5) The label of "DC biasing network" in Figure 1(d) is not clear enough, so it is recommended to add a local enlarged image or text description.
(6)There is no mention of intermodulation interference or crosstalk in the case of multi-unit cooperative control, and it is recommended to supplement the relevant analysis.
This paper has clear value at the technical and application level, but it needs to be improved to address the above problems, especially the consistency of experimental data, the description of key parameters and the accuracy of expression. Suggested is: Minor Revision
Author Response
Dear reviewer,
We would like to thank you for the helpful comments and suggestions. The manuscript (ID: photonics-3520938) has been revised carefully according to the comments and suggestions. Blue highlighted text is used to show where changes have been made in the manuscript. We hope that the revisions can meet the requirement of this publication.
Thank you very much again for all your suggestions and comments!
Author Response File: Author Response.pdf
This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
A beam direction reconfigurable LWA is proposed in this manuscript. The different statuses of the PIN diodes can achieve the beam steering range of 63°. In general, this work is not well presented in the manuscript. There is no detailed design procedure, and the performance of the antenna is also limited. Hence, rejection is recommended. Some comments are as follows:
1. The operating mechanism of the antenna should be further improved. In section II, authors illustrate that the square pin arrays can excite slow-wave propagation in the LWA. However, there is no dispersion characteristic analysis. Please do the simulation.
2. I am wondering how to generate the circularly polarized radiation by the circular split-ring-shape patch.
3. The function of the groove gap waveguide is not well explained, due to the fact that a traditional rectangle waveguide can realize the same performance as the GGW.
4. For the leaky-wave antenna design, the suppression of the open stop band is a key issue. Please do some discussion.
5. The fabricated prototype is indispensable to verify the feasibility of this work.
Reviewer 2 Report
Comments and Suggestions for Authors
In the submitted manuscript, the authors study a circularly polarized LWA with fix-frequency beam-scanning for Ka band applications. A beam scanning range of 63° is then realized, with good CP and a peak gain of 17.1dBi, which makes the antenna a good candidate in electronic and optical applications. Some comments should be addressed as listed below.
- Fig. 1 should be re-plotted by some sub-figures. Besides, the overall top and side views should be added clearly by each element of antennas.
- The PIN diodes of antennas should be marked clearly and its performances should be studied independently in the text.
- The final gain of antenna is not very high. How to improve the antenna gain furthermore? Some works may be useful such as: Optics and Lasers in Engineering 147 (2021): 106734.
- There are only simulations results in this work. How about the fabricated sample and measurements? There should be some discussions.
- The scanning angle of 3dB gain of the proposed antenna should be given and compared with each other at different operation frequency. Besides, the wide-angle performances should compared to some recent works such as: Materials & Design 240 (2024): 112879.
- Some typos should be revised through the manuscript, e. g.: in the abstract, "spacial"; in Part 2, "The configuration and structural parameters of the proposed antenna is given Fig.1", "is" should be changed to "are" and many others.
Comments on the Quality of English Language
well
Reviewer 3 Report
Comments and Suggestions for Authors
The work designs a beam-scanning leaky-wave antenna (LWA) with circular polarization (CP) based on a groove gap waveguide (GGW). While the concept is interesting, several theoretical and practical issues need to be addressed.
1. The description of the antenna structure is unclear, making it difficult to fully evaluate the work. Moreover, the provided structural diagram (Fig. 1) are not sufficiently detailed, and the images lack clarity, preventing an accurate assessment of the proposed configuration. A more precise and high-resolution depiction including labeled dimensions and component details, is necessary.
2. The authors claim that beam scanning is achieved by adjusting the periodicity of the radiating elements, yet it lacks a detailed dispersion analysis to support FFBS. The role of the GGW in maintaining a stable phase constant is not sufficiently explained. In addition, although the authors acknowledge in the Introduction section that the open stopband (OSB) is a critical issue in beam scanning for LWAs, they do not provide a thorough discussion of how their proposed design addresses this challenge.
3. The PIN diode model is simplified without considering parasitic effects at mm-wave frequencies, which may impact performance. The lack of discussion on diode losses and switching speed raises concerns about the feasibility of implementation.
4. The study is entirely based on CST simulations, with no fabrication or measurement data to support the claims. At least a feasibility discussion on the implementation challenges of the proposed design is needed.
Comments on the Quality of English Language
The English could be improved.
