Round 1

Reviewer 1 Report

The authors presented a wide-angle pattern diversity antenna system for mmWave 5G mobile terminals. The proposed antenna has an acceptable gain variation between 6 up to 11dBi and a mutual coupling of about 10 dB.

I appreciate the work that the authors have been done. However, this article missed some of the essential principles that need to be solved, as follows:

Abstract:

1. The authors are required to name the type of proposed antenna. Is it patch antenna, monopole antenna or patch array antenna?

Introduction:

2. The introduction is incomplete.

The authors are required to summarize the literature with the recently published articles regarding patch antennas. Please add more references about the planar antennas and explain some of their performances in terms of (size, gain, etc.) [1-4]

[1] Double Overt-Leaf Shaped CPW-Fed Four Port UWB MIMO Antenna" Electronics 10, no. 24: 3140.

[2]High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications. CMC-Computers, Materials & Continua, 70(1), 1419–1436.

[3]A Sub-6 GHz MIMO Antenna Array for 5G Wireless Terminals" Electronics 10, no. 24: 3062. 

[4] Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications" Electronics 10, no. 18: 2184. 

3. Please list the research novelty of the proposed paper?

Proposed Pattern Diversity Antenna

4. Again, please provide the type of the proposed antenna. Is it patch antenna, monopole antenna or patch array antenna?

5. To validate the design procedure, the authors must do a parametric study of the proposed antenna in terms of S11, starting from the single element?

6. It is essential to provide the gain and the efficiency of the proposed antenna?

7. Table1 doesn't make sense at all. The authors are required to make a comparison for the important antenna parameters, such as:

a- Antenna Size

b- Mutual coupling

c- Antenna efficiency

Conclusion

8. The conclusion is too short. More concluded results are required. Please rewrite again?

That's all for me.

Author Response

Respected Editors,

The authors would like to thank the reviewers for the detailed review of our manuscript entitled, “A wide angle pattern diversity antenna system for mmWave 5G mobile terminals (15874441)”. The reviewers’ comments followed by the revisions done in the manuscript are given below for your kind perusal.

Thanking you,                                                           

Yours sincerely,

Issa Elfergani

Comments:

Reviewer: 1

1:  the proposed design has no inherent beam scanning ability so why is it better than phased arrays?

Comments and Suggestions for Authors

The authors presented a wide-angle pattern diversity antenna system for mmWave 5G mobile terminals. The proposed antenna has an acceptable gain variation between 6 up to 11dBi and a mutual coupling of about 10 dB.

I appreciate the work that the authors have been done. However, this article missed some of the essential principles that need to be solved, as follows:

Response:  The research objective of the proposed design is to achieve wide angular coverage without compromise in the gain. Conventional phased arrays would achieve high gain only in the boresight axis and would suffer from scanning loss as the beam is tilted away from the primary radiating axis. The proposed design offers wider angular coverage compared to the conventional phased arrays without the use of phase shifters. Phase shifters integrated with antenna elements would be typically narrowband, hence would fail to offer the wide angular coverage for a broad bandwidth. As the proposed design has three ports feeding the electrically compact design, the proposed shared radiator design delivers wider angular coverage for the occupied physical aperture compared to its phased array counterpart.

Abstract:

1. The authors are required to name the type of proposed antenna. Is it patch antenna, monopole antenna or patch array antenna?

 Response:  The proposed antenna is a corporate fed inset fed patch antenna array with multiple ports. The suggested change has been incorporated in the manuscript.

Introduction:

2. The introduction is incomplete.

The authors are required to summarize the literature with the recently published articles regarding patch antennas. Please add more references about the planar antennas and explain some of their performances in terms of (size, gain, etc.) [1-4]

[1] Double Overt-Leaf Shaped CPW-Fed Four Port UWB MIMO Antenna" Electronics 10, no. 24: 3140.

[2]High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications. CMC-Computers, Materials & Continua, 70(1), 1419–1436.

[3]A Sub-6 GHz MIMO Antenna Array for 5G Wireless Terminals" Electronics 10, no. 24: 3062.

[4] Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications" Electronics 10, no. 18: 2184.

Response:  The suggested references have been incorporated in the bibliography. The modified section of introduction is recreated here

Gain switch ability is required in mmWave 5G systems to cater to broadcast and data link modes. In the broadcast mode, low gain or wide beam antenna is required and in da-ta link mode: high gain or narrow beam is required. The same could be realized using phased arrays by selectively firing up the designated ports [10-11]. The CPW (coplanar waveguide) fed antenna design of [12] works in the microwave band, the authors have demonstrated orthogonal polarization system, the same concept might not be applicable in the mmWave regime. Similarly, the design concept of [13] would lead to bidirectional radiation patterns, when the antenna is scaled up to millimeter wave frequencies. The corporate fed array illustrated in [14] would occupy larger physical footprint, when de-signed for the 28GHz band. But the design and deployment of phased arrays would be expensive. Therefore, an electrically compact three port wide angular coverage shared ground antenna system is proposed in this paper. 

3. Please list the research novelty of the proposed paper?

Response:  The suggested revision has been incorporated in the manuscript as follows:

The novel features of the proposed antenna design are listed below:

• Shared radiator design with minimal physical footprint
• Shared ground design which is compatible with the system ground plane of the typical commercial device
• Conformal shared radiator design which could be panel mountable with commercially available smartphones
• Wide angular coverage with three ports without the use of phase shifters
• Achievement of high gain for the respective port for minimal occupied physical footprint

Proposed Pattern Diversity Antenna

4. Again, please provide the type of the proposed antenna. Is it patch antenna, monopole antenna or patch array antenna?

Response: The proposed antenna is a corporate fed inset fed patch antenna array with multiple ports. The suggested change has been incorporated in the manuscript.

5. To validate the design procedure, the authors must do a parametric study of the proposed antenna in terms of S11, starting from the single element?

Response: The concept of inset fed patch antenna designed on an electrically thin substrate is well-known and standard [R1], hence the authors would like to politely omit the parametric study as it does not convey much novelty in the design aspect.

R1. Stutzman, Warren L., and Gary A. Thiele. Antenna theory and design. John Wiley &        Sons, 2012.

6. It is essential to provide the gain and the efficiency of the proposed antenna?

Response:  The radiation efficiency curve is included in the revised manuscript

7. Table 1 doesn't make sense at all. The authors are required to make a comparison for the important antenna parameters, such as:

a- Antenna Size

b- Mutual coupling

c- Antenna efficiency

Response: The table has been modified as per the suggestion.

*Ref=Reference, Frq= Frequency (GHz), AS = Antenna size (in mmxmm), MC= Mutual coupling (dB),  ERV =Effective Radiating Volume (λ₀³), AE = Antenna Efficiency (%) G=Gain (dBi), GS = Gain Switchability, MI = Mobile Integration, Con = Conformal, SG = Shared Ground, PRW = Proposed Work

Conclusion

8. The conclusion is too short. More concluded results are required. Please rewrite again?

 Response:  The conclusion has been rewritten as follows:

A three port conformal antenna system operating in the 28GHz is proposed, wherein a standard 50Ω line is fed to the two-way power divider, which in turn is connected to the four-way power divider. The four-way power divider is loaded with four inset fed patch antennas operating in the 28GHz band. The corner elements of the corporate fed array are in turn connected to the two ports through impedance transformers. Port 1 excitation would lead to a high gain –narrow beam mode preferable for data link and Ports 2 or 3 excitation would lead to a low gain – wide beam mode preferable for broadcast application. A wide angular coverage of 100º is achieved for various excitations of the ports with-in the shared radiator antenna system. Mutual coupling is less than 10dB across the spectrum and across the ports, in spite of the electrically connected structure. The proposed antenna could be a potential candidate for future 5G applications. 

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors presented a pretty solid paper on a 5G mm-wave antenna system with wide coverage. The article is interesting and seems to retain enough novelty to be worthy of a publication.

However I would like to share some thoughts with the authors.

1) The writing is sometimes awkward, please check and revise the paper carefully;

2) There is a major problem with the radiation pattern when port 3 is fed. The measured results show that the back lobes are really high. This problem needs to be adressed with high priority.

3) Line 161: it is stated that the mutual coupling is less than 10 dB. This is because you are referring to the simulated results, but you should consider the measured ones. Hence the mutual coupling is less than 15 dB (this is actually an improvement!).

4) The gain is reported in Fig. 7, but it is not explained if the result is simulated or measured. The smoothness of the curve suggest a simulated result. If I am correct, please provide the measured results (at least for a few frequencies within the operating bandwidth).

5) The comparison with other published works is fine, but it would be preferable to have a benchmark also on the angular coverage, which is your primary selling point.

6) The conclusion section seems a little bit rushed. Maybe you should put more effort in its drafting.

Author Response

Respected Editors,

The authors would like to thank the reviewers for the detailed review of our manuscript entitled, “A wide angle pattern diversity antenna system for mmWave 5G mobile terminals (15874441)”. The reviewers’ comments followed by the revisions done in the manuscript are given below for your kind perusal.

Thanking you,                                                     

Yours sincerely,

Issa Elfergani

Comments:

Reviewer 2

Comments and Suggestions for Authors

The authors presented a pretty solid paper on a 5G mm-wave antenna system with wide coverage. The article is interesting and seems to retain enough novelty to be worthy of a publication.

Response: The authors are grateful for the comment

However I would like to share some thoughts with the authors.

• The writing is sometimes awkward, please check and revise the paper carefully;

Response: The entire manuscript has been revised as per the suggestion

• There is a major problem with the radiation pattern when port 3 is fed. The measured results show that the back lobes are really high. This problem needs to be addressed with high priority.

Response: The higher back lobe specifically for excitation of port 3 is due to the following reasons:

• Dual bending of the substrate which creates cracks within the copper trace of the feeding network, hence leading to radiation leakages from the discontinuities.
• Faulty assembly of the electrically large connector with the feeding line corresponding to port 3, leading to poor transition from the trace pin of the connector to the feed line.

• Line 161: it is stated that the mutual coupling is less than 10 dB. This is because you are referring to the simulated results, but you should consider the measured ones. Hence the mutual coupling is less than 15 dB (this is actually an improvement!).

Response: The suggested revision has been incorporated in the manuscript

• The gain is reported in Fig. 7, but it is not explained if the result is simulated or measured. The smoothness of the curve suggests a simulated result. If I am correct, please provide the measured results (at least for a few frequencies within the operating bandwidth).

 Response:  The measured curves has been integrated with the simulated curves as shown

• The comparison with other published works is fine, but it would be preferable to have a benchmark also on the angular coverage, which is your primary selling point.

Response: The table has been modified according to the suggestion

*Ref=Reference, Frq= Frequency (GHz), AS = Antenna size (in mm x mm), MC= Mutual coupling (dB),  ERV =Effective Radiating Volume (λ₀³), AE = Antenna Efficiency (%), AC = Angular coverage (º) G=Gain (dBi), GS = Gain Switchability, MI = Mobile Integration, Con = Conformal, SG = Shared Ground, PRW = Proposed Work

• The conclusion section seems a little bit rushed. Maybe you should put more effort in its drafting.

Response: The conclusion has been rewritten as follows:

A three port conformal antenna system operating in the 28GHz is proposed, wherein a standard 50Ω line is fed to the two-way power divider, which in turn is connected to the four-way power divider. The four-way power divider is loaded with four inset fed patch antennas operating in the 28GHz band. The corner elements of the corporate fed array are in turn connected to the two ports through impedance transformers. Port 1 excitation would lead to a high gain –narrow beam mode preferable for data link and Ports 2 or 3 excitation would lead to a low gain – wide beam mode preferable for broadcast application. A wide angular coverage of 100º is achieved for various excitations of the ports with-in the shared radiator antenna system. Mutual coupling is less than 10dB across the spectrum and across the ports, in spite of the electrically connected structure. The proposed antenna could be a potential candidate for future 5G applications. 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors

Thank you for your efforts to revise all the suggested comments, making your article look better. However, there are errors with the references [12,13,14,15], please write it correctly as follows:

[12] Agarwal, S.; Rafique, U.; Ullah, R.; Ullah, S.; Khan, S.; Donelli, M. Double Overt-Leaf Shaped CPW-Fed Four Port UWB MIMO Antenna. Electronics. 2021, 10, 3140.

[13] Al-Gburi, A.J.A.; Ibrahim, I.B.M.; Zakaria, Z.; Ahmad, B.H.; Bin Shairi, N.A.; Zeain, M.Y. High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications. Comput. Mater. Contin. 2022, 70, 1419–1436.

[14] Khan, J.; Ullah, S.; Tahir, F.A.; Tubbal, F.; Raad, R. A Sub-6 GHz MIMO Antenna Array for 5G Wireless Terminals. Electronics. 2021, 10, 3062.

[15] Arumugam, S.; Manoharan, S.; Palaniswamy, S.K.; Kumar, S. Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications. Electronics. 2021, 10, 2184.

Author Response

Respected Editors,

The authors would like to thank the reviewers for the detailed review of our manuscript entitled, “A wide angle pattern diversity antenna system for mmWave 5G mobile terminals (15874441)”. The reviewers’ comments followed by the revisions done in the manuscript are given below for your kind perusal.

Thanking you,                                                                          

Yours sincerely,

Issa Elfergani

Review 1

Comments and Suggestions for Authors

Dear Authors

Thank you for your efforts to revise all the suggested comments, making your article look better. However, there are errors with the references [12,13,14,15], please write it correctly as follows:

[12] Agarwal, S.; Rafique, U.; Ullah, R.; Ullah, S.; Khan, S.; Donelli, M. Double Overt-Leaf Shaped CPW-Fed Four Port UWB MIMO Antenna. Electronics. 2021, 10, 3140.

[13] Al-Gburi, A.J.A.; Ibrahim, I.B.M.; Zakaria, Z.; Ahmad, B.H.; Bin Shairi, N.A.; Zeain, M.Y. High Gain of UWB Planar Antenna Utilising FSS Reflector for UWB Applications. Comput. Mater. Contin. 2022, 70, 1419–1436.

[14] Khan, J.; Ullah, S.; Tahir, F.A.; Tubbal, F.; Raad, R. A Sub-6 GHz MIMO Antenna Array for 5G Wireless Terminals. Electronics. 2021, 10, 3062.

[15] Arumugam, S.; Manoharan, S.; Palaniswamy, S.K.; Kumar, S. Design and Performance Analysis of a Compact Quad-Element UWB MIMO Antenna for Automotive Communications. Electronics. 2021, 10, 2184.

Response:  Thanks for pointing this, all references were written as requested. Please refer to the revised version.

Author Response File: Author Response.pdf

Reviewer 2 Report

Thank you for addressing all my comments. The paper is now ready to be published in my opinion.

Author Response

Respected Editors,

The authors would like to thank the reviewers for the detailed review of our manuscript entitled, “A wide angle pattern diversity antenna system for mmWave 5G mobile terminals (15874441)”. The reviewers’ comments followed by the revisions done in the manuscript are given below for your kind perusal.

Thanking you,                                                                          

Yours sincerely,

Issa Elfergani

Reviewer 2

Comments and Suggestions for Authors

Thank you for addressing all my comments. The paper is now ready to be published in my opinion.

Response:  Thanks for your response.

Author Response File: Author Response.pdf