A compact co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems

Tan Dao-Duc; Duc-Nguyen Tran-Viet; Dat Nguyen Tien; Dinh Nguyen Quoc; Tung The-Lam Nguyen; Hung Tran-Huy

doi:10.1371/journal.pone.0304414

Peer Review History

Original SubmissionFebruary 9, 2024
26 Mar 2024 Decision Letter - Maharana Pratap Singh, Editor PONE-D-24-05575A compact co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systemsPLOS ONE Dear Dr. Tran-Huy, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by May 10 2024 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. 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Additional Editor Comments: Dear Dr. Hung Tran-Huy, I am writing in regards to manuscript No PONE-D-24-05575 entitled “A compact co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems” which you submitted to the PLOS ONE. Your manuscript has been reviewed by several experts in the field. Based on the recommendations given by reviewers found at the bottom of this letter, I suggest you to please address the questions raised by the reviewers. Reviewer 1: This paper proposes a compact design of dual-sense circularly polarized for simultaneous transmit (Tx) and receive (Rx) communication systems. The high Tx-Rx isolation can be achieved by tuning the feeding positions. There are some major issues that raise my concerns. 1. Undoubtedly, the isolation of the transmitting and receiving ports is a critical parameter for a STAR antenna. Although the article explains how to achieve high Tx-Rx isolation by merely adjusting the feed position, its decoupling mechanism is not explicitly described. To enhance the reader's comprehension, kindly provide a comprehensive description of this. Also, could you please state what challenges there are for the decoupling problem of dual circularly polarized antennas with the same aperture? 2. In contrast to the co-aperture dual-sense CP antennas that are comparable in size, the antenna proposed in the article possesses the most limited bandwidth. Could you please provide an explanation as to why? 3. More comprehensive results need to be provided so that readers can clearly understand the effectiveness of the proposed antenna, such as antenna efficiency, envelope correlation coefficient, and radiation pattern of both ports. 4. In Figure 12, it can be clearly observed that the tested S21 is better than the simulated one. Is this phenomenon coincidental? If not, then elucidate this. 5. There are many grammar mistakes in this paper. For example, The last paragraph of the introduction. "In this paper, the dual CP antenna with size miniaturization is concentrated. The proposed STR antenna employs 2 ×2 unit-cell MS as the co-aperture to achieve compact size. ". Page 4, third line of the first paragraph, "Fig. 7shows the geometry of the proposed dual-sense CP antenna." Please add a space after 7. Reviewer 2: Dear authors, In the manuscript, a co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems is proposed. I have some questions. 1. The manuscript should be well polished. There are several grammatical mistakes. 2. In Fig.6, it shoule be pointed that which curve represents axial ration and which curve represents s11. There are some curves in Fig. 13 and it also should be pointed what these curves represent. 3. I think the antenna is not suitable for simultaneous transmit and receive systems because the antenna's bandwidth is determined by a standard of 10-dB isolation. STAR antennas should have high isolations between the TX and RX ports. Please make a thorough review to check it. 4. Why the isolation is up to 39 dB at 2.46 GHz and the isolation are very low in other frequencies? What's the principle behind this? [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Yes Reviewer #2: Yes ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: Yes ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: Yes ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: This paper proposes a compact design of dual-sense circularly polarized for simultaneous transmit (Tx) and receive (Rx) communication systems. The high Tx-Rx isolation can be achieved by tuning the feeding positions. There are some major issues that raise my concerns. 1. Undoubtedly, the isolation of the transmitting and receiving ports is a critical parameter for a STAR antenna. Although the article explains how to achieve high Tx-Rx isolation by merely adjusting the feed position, its decoupling mechanism is not explicitly described. To enhance the reader's comprehension, kindly provide a comprehensive description of this. Also, could you please state what challenges there are for the decoupling problem of dual circularly polarized antennas with the same aperture? 2. In contrast to the co-aperture dual-sense CP antennas that are comparable in size, the antenna proposed in the article possesses the most limited bandwidth. Could you please provide an explanation as to why? 3. More comprehensive results need to be provided so that readers can clearly understand the effectiveness of the proposed antenna, such as antenna efficiency, envelope correlation coefficient, and radiation pattern of both ports. 4. In Figure 12, it can be clearly observed that the tested S21 is better than the simulated one. Is this phenomenon coincidental? If not, then elucidate this. 5. There are many grammar mistakes in this paper. For example, The last paragraph of the introduction. "In this paper, the dual CP antenna with size miniaturization is concentrated. The proposed STR antenna employs 2 ×2 unit-cell MS as the co-aperture to achieve compact size. ". Page 4, third line of the first paragraph, "Fig. 7shows the geometry of the proposed dual-sense CP antenna." Please add a space after 7. Reviewer #2: Dear authors, In the manuscript, a co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems is proposed. I have some questions. 1. The manuscript should be well polished. There are several grammatical mistakes. 2. In Fig.6, it shoule be pointed that which curve represents axial ration and which curve represents s11. There are some curves in Fig. 13 and it also should be pointed what these curves represent. 3. I think the antenna is not suitable for simultaneous transmit and receive systems because the antenna's bandwidth is determined by a standard of 10-dB isolation. STAR antennas should have high isolations between the TX and RX ports. Please make a thorough review to check it. 4. Why the isolation is up to 39 dB at 2.46 GHz and the isolation are very low in other frequencies? What's the principle behind this? ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No ******** [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. Attachments Attachment Submitted filename: Comments to the Author.docx https://doi.org/10.1371/journal.pone.0304414.r001
Revision 1
7 Apr 2024 Author Response Original Manuscript ID: PONE-D-24-05575 Original Article Title: “A compact co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems” To: Reviewer Re: Response to reviewer Dear Reviewer, We appreciate you for your precious time in reviewing our paper and providing valuable comments. It was your valuable and insightful comments that led to possible improvements in the current version. The authors have carefully considered the comments and tried our best to address every one of them. We are uploading our point-by-point response to the comments, an updated manuscript with red highlighting indicating changes, and a manuscript without track changes. Best regards, Reviewer 1: This paper proposes a compact design of dual-sense circularly polarized for simultaneous transmit (Tx) and receive (Rx) communication systems. The high Tx-Rx isolation can be achieved by tuning the feeding positions. There are some major issues that raise my concerns. Comment 1: Undoubtedly, the isolation of the transmitting and receiving ports is a critical parameter for a STAR antenna. Although the article explains how to achieve high Tx-Rx isolation by merely adjusting the feed position, its decoupling mechanism is not explicitly described. To enhance the reader's comprehension, kindly provide a comprehensive description of this. Also, could you please state what challenges there are for the decoupling problem of dual circularly polarized antennas with the same aperture. Author response: The authors would like to thank the Reviewer for your very constructive comment. Initially, the radiation principle of the proposed antenna is restated for Reviewer’s convenience. According to the discussion in Section “Single-port MS-based antenna”, the proposed antenna has two main parts including the CP source and the radiating element. Here, the radiating element is the MS layer, which determines the resonant frequency of the antenna. Meanwhile, as the MS layer is a combination of multiple symmetric unit cells, it cannot radiate CP wave itself. Thus, the CP source is necessary, and it is tuned accompanied by the MS to achieve good performance at the desired band. Regarding the decoupling mechanism, the MS plays an important role in determining the inter-port isolation of the proposed design. Fig. 1R shows the current distributions on the CP source at 2.46 GHz for different cases of with and without MS. Fig. 1R. Simulated current distributions at 2.46 GHz with and without the MS. It can be seen obviously that with the presence of the MS, the field on the CP source is significantly redistributed and the intensity field is weak at the Port-2 feeding branch. This is due to the MS is designed to well resonate at 2.46 GHz. It can be verified by observing Fig. 4b in the revised manuscript, the modal significance is approximately 1 at 2.46 GHz. At this frequency, the electromagnetic field from the CP source tends to couple with the MS, rather than the Port-2 feeding branch, leading to high inter-port isolation. Out of the frequency band around 2.46 GHz, the field distribution on the CP source is changed significantly, as demonstrated in Fig. 2R. Fig. 2R. Simulated current distributions on the patch at different frequencies. As shown in Fig. 2R, the field distributions on the CP source are significantly different at different frequencies. At 2.4 and 2.5 GHz, strong currents are observed on the Port-2 feeding branch, resulting in high isolation (as seen in Fig. 8a of the revised manuscript). This is attributed to the MS, which doesn’t resonate at these frequencies due to the low modal significance values of less than 0.4 (shown in Fig. 4b of the revised manuscript). Thus, the isolation performance at these frequencies is worse than 2.46 GHz. To conclude, the decoupling mechanism of the proposed MS-based antenna strongly depends on the MS. At the resonant frequency (determined by the MS), the feeding position of Port-2 is tuned to achieve the best isolation performance (shown in Fig. 9b of the revised manuscript). With respect to the challenges for the decoupling of dual circularly polarized antennas with the same aperture, it is indeed much more difficult than decoupling dual CP antennas with different apertures (like two-port MIMO antenna). Here, the port spacing is small and the coupling is very strong due to the use of the same radiating aperture. Author action: The decoupling mechanism is further discussed in Paragraph 2, Section “Dual-sense CP two-port MS-based antenna” of the revised manuscript. Figs. 1R and 2R are also included in the revised manuscript as Figs. 9 and 10. The challenging in decoupling of co-aperture antenna is mentioned in Paragraph 3, Section “Introduction”. Comment 2: In contrast to the co-aperture dual-sense CP antennas that are comparable in size, the antenna proposed in the article possesses the most limited bandwidth. Could you please provide an explanation as to why? Author response: In fact, the small antenna will have relatively low radiation resistance or high Q-factor, leading to very narrow BW. As this paper focuses on compact designs, there is a trade-off with operating BW. However, despite having the smallest overall dimensions, the proposed antenna can achieve high isolation and comparable gain as well. Note that for compact design, the decoupling is more difficult as the short distance between two ports. Author action: Further discussion about the performance of the proposed antenna is added to Paragraph 4, Section “Measurement results” of the revised manuscript. Comment 3: More comprehensive results need to be provided so that readers can clearly understand the effectiveness of the proposed antenna, such as antenna efficiency, envelope correlation coefficient, and radiation pattern of both ports. Author response: The authors would like to thank the Reviewer for your constructive comment. Regarding the antenna efficiency, the simulated value is about 84%. In measurement, the antenna efficiency was not measured due to the limit of the chamber; however, it can still be estimated based on the realized gain measurements (Fig. 13). The gain difference between simulation and measurement is about 0.3 dBi. Thus, the calculated measured efficiency is about 76%. Author action: The radiation efficiency is mentioned in Paragraph 2, Section “Measurement results”. The ECC is discussed in Paragraph 1, Section “Dual-sense CP two-port MS-based antenna”. Regarding the radiation pattern, as the antenna is symmetric, the radiation patterns with Port-2 excitation is like Port-1. Thus, the authors believe that showing radiation pattern with Port-1 is proper. This is highlighted in Paragraph 3, Section “Measurement results”. Comment 4: In Figure 12, it can be clearly observed that the tested S21 is better than the simulated one. Is this phenomenon coincidental? If not, then elucidate this. Author response: In fact, there always exists a difference between simulations and measurements. Sometimes simulated results are better and vice versa. Thus, the authors believe that this phenomenon is just coincidence. Comment 5: There are many grammar mistakes in this paper. For example, The last paragraph of the introduction. "In this paper, the dual CP antenna with size miniaturization is concentrated. The proposed STR antenna employs 2 ×2 unit-cell MS as the co-aperture to achieve compact size. ". Page 4, third line of the first paragraph, "Fig. 7shows the geometry of the proposed dual-sense CP antenna." Please add a space after 7. Author response: The author would like to thank the Reviewer for pointing out our grammatical mistakes. Author action: The grammar is thoroughly checked. Reviewer 2: In the manuscript, a co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems is proposed. I have some questions. Author response: The author would like to thank the Reviewer for pointing out our grammatical mistakes. Author action: The grammar is thoroughly checked in the revised manuscript. Comment 2: In Fig.6, it should be pointed that which curve represents axial ration and which curve represents s11. There are some curves in Fig. 13 and it also should be pointed what these curves represent. Author response: The author would like to thank the Reviewer for the constructive comment. Author action: Fig. 6 and Fig. 13 are modified in the revised manuscript. Comment 3: I think the antenna is not suitable for simultaneous transmit and receive systems because the antenna's bandwidth is determined by a standard of 10-dB isolation. STAR antennas should have high isolations between the TX and RX ports. Please make a thorough review to check it. Author response: The author would like to thank the Reviewer for the constructive comment. As reported in the literature, self-interference is the most critical challenge to the development of STAR systems and high isolation is needed, as considered in [1R]. However, the cancellation techniques should be deployed to all related domains, including antenna/propagation domain, analog domain and digital domain. In this study, although the peak isolation is significantly high, at 39 dB, the 20-dB isolation bandwidth is about 10 MHz. Hence, the proposed design could be applied to STAR applications that need narrow-band operations, such as Zigbee with 2 MHz-channel and Bluetooth with 5 MHz-channel. Similar isolation performance is also observed in [20], which is designed for STAR communication. Thus, the authors believe that the proposed design could be suitable for STAR applications. Author action: The possible application of the proposed antenna is added to Section “Conclusion”. [1R] Chen, Y.; Ding, C.; Jia, Y.; Liu, Y. Antenna/Propagation Domain Self-Interference Cancellation (SIC) for In-Band Full-Duplex Wireless Communication Systems. Sensors 2022, 22, 1699. Comment 4: Why the isolation is up to 39 dB at 2.46 GHz and the isolation are very low in other frequencies? What's the principle behind this? Author response: The authors would like to thank the Reviewer for your very constructive comment. The decoupling mechanism of the proposed design is further investigated. Initially, for Reviewer’s convenience, the radiation principle of the proposed antenna is restated. According to the discussion in Section “Single-port MS-based antenna”, the proposed antenna has two main parts including the CP source and the radiating element. Here, the radiating element is the MS layer, and the resonant frequency is determined by this layer. Meanwhile, as the MS layer is a combination of multiple symmetric unit cells, it cannot radiate CP wave. Thus, the CP source is necessary, and it is tuned accompanied by the MS to achieve good performance at the desired band. Regarding the decoupling mechanism, the MS plays an important role in determining the inter-port isolation of the proposed design. Fig. 3R shows the current distribution on the CP source at 2.46 GHz with and without MS. Fig. 3R. Simulated current distributions at 2.46 GHz with and without the MS. It can be seen obviously that with the presence of the MS, the field on the patch is significantly redistributed and the intensity field is weak at the Port-2 feeding branch. This is due to the MS is designed to well resonate at 2.46 GHz. It can be verified by observing Fig. 4b in the revised manuscript, the modal significance is approximately 1 at 2.46 GHz. At this frequency, the electromagnetic field from the CP source tends to couple with the MS, rather than the Port-2 feeding branch, leading to high inter-port isolation. Out of the frequency band around 2.46 GHz, the field distribution on the CP source is changed significantly, as demonstrated in Fig. 4R. Fig. 4R. Simulated current distributions on the patch at different frequencies. As shown in Fig. 4R, the field distributions on the CP source are significantly different at different frequencies. At 2.4 and 2.5 GHz, strong currents are observed on the Port-2 feeding branch, resulting in high isolation (as seen in Fig. 8a of the revised manuscript). This is attributed to the MS, which doesn’t resonate at these frequencies due to the low modal significance values of less than 0.4 (shown in Fig. 4b of the revised manuscript). Thus, the isolation performance at these frequencies is worse than 2.46 GHz. To conclude, the decoupling mechanism of the proposed MS-based antenna strongly depends on the MS. At the resonant frequency (determined by the MS), the feeding position of Port-2 is tuned to achieve the best isolation performance (shown in Fig. 9b of the revised manuscript). Author action: The decoupling mechanism is further discussed in Paragraph 2, Section “Dual-sense CP two-port MS-based antenna” of the revised manuscript. Figs. 1R and 2R are also included in the revised manuscript as Figs. 9 and 10. Attachments Attachment Submitted filename: Response to Reviewers.docx https://doi.org/10.1371/journal.pone.0304414.r002
13 May 2024 Decision Letter - Maharana Pratap Singh, Editor A compact co-aperture dual-sense circularly polarized antenna for simultaneous transmit and receive systems PONE-D-24-05575R1 Dear Dr. Tran-Huy, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. If you have any questions relating to publication charges, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Maharana Pratap Singh, Ph.D. Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0304414.r003
Formally Accepted
25 Jun 2024 Acceptance Letter - Maharana Pratap Singh, Editor PONE-D-24-05575R1 PLOS ONE Dear Dr. Tran-Huy, I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team. At this stage, our production department will prepare your paper for publication. This includes ensuring the following: * All references, tables, and figures are properly cited * All relevant supporting information is included in the manuscript submission, * There are no issues that prevent the paper from being properly typeset If revisions are needed, the production department will contact you directly to resolve them. If no revisions are needed, you will receive an email when the publication date has been set. At this time, we do not offer pre-publication proofs to authors during production of the accepted work. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few weeks to review your paper and let you know the next and final steps. Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. If we can help with anything else, please email us at customercare@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Dr. Maharana Pratap Singh Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0304414.r004

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