Wideband Eight-Antenna Array Designs for 5G Smartphone Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript provided outlines a novel design for a broadband eight-antenna array tailored for Fifth Generation (5G) New Radio (NR) smartphone applications. Here are some comments:

 

Relevance and Innovation:

 

The paper addresses a critical need in modern telecommunication by proposing an antenna array design specifically for 5G NR applications, which is highly relevant given the global push towards 5G adoption.

Technical Specificity:

 

The use of a modified loop antenna element (MLAE) that can generate three different loop modes is a notable technical innovation. This approach helps in covering a wide frequency range, which is essential for supporting various 5G bands, particularly n77/n78/n79 and n46.

Performance Metrics:

 

The experimental results provided are quite impressive. The array's ability to maintain an overlapping 6-dB bandwidth covering 3300–5925 MHz, with isolation and antenna efficiency greater than 10 dB and 40%–90%, respectively, indicates robust performance.

MIMO Performance:

 

The paper emphasizes good MIMO performance, demonstrated by an envelope correlation coefficient (ECC) lower than 0.1 and a high channel capacity of 37–40 bps/Hz. These metrics are crucial for achieving high data rates and reliable connections in 5G networks.

Practical Implications:

 

By focusing on the practical implementation in smartphones, the paper bridges the gap between theoretical research and real-world application, making the findings highly valuable for industry stakeholders.

Overall, the abstract succinctly presents a significant advancement in antenna array design for 5G applications, highlighting both the technical details and the practical benefits of the proposed solution.

 

Some suggestions for improvements and potential directions:

 

Antenna Efficiency:

 

While the measured efficiency ranging from 40% to 60% is acceptable, there is room for improvement. Future work could focus on optimizing the antenna design to increase efficiency, especially at the upper and lower ends of the frequency range.

 

Isolation:

 

Isolation exceeding 10 dB is good, but further increasing this value could reduce interference between antennas. Advanced design techniques, such as the use of metamaterials or decoupling elements, could be explored.

 

Miniaturization:

 

Given the application in smartphones, reducing the physical size of the antenna without compromising performance is crucial. Research into high permittivity materials or compact structures could be beneficial.

 

Tests:

Testing and adjusting the antenna’s performance in different propagation environments (urban, indoor, rural) to ensure consistent and robust performance in various real-world scenarios.

Considering the energy efficiency and sustainability of the antenna design by investigating materials and manufacturing techniques that reduce environmental impact and energy consumption.

 

Simulation:

Utilizing advanced simulation and modeling techniques to predict and improve antenna performance in real-world conditions, including the influence of adjacent smartphone components and human body interaction. 

 

Future Work

Investigating the compatibility and performance of the antenna in other emerging 5G bands, as well as future 6G bands, can enhance the versatility of the design.

Studying the integration of the antenna with other wireless communication technologies, such as Wi-Fi 6/7, Bluetooth, and IoT, to offer a more comprehensive and multifunctional solution.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Please find the review report in the attached pdf.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors This manuscript presents a design of eight-antenna array for 5G smartphone applications with good MIMO performance. Simulated results basically follow the measured results. Simulated ECC values of the proposed eight-antenna array are reasonably compared with the measured results. Careful comparison with existing antennas clearly shows that the proposed antenna has good performances across the 5G NR band 350 n77/n78/n79 and 5G NR-U band n46. The designed wideband eight-antenna array is interesting and should be useful for real applications. It is acceptable for publication.

By the way, it would be more interesting to include the design principle of the proposed antenna and how to determine the geometry parameters of the proposed antenna. As a MIMO antenna system, please also explain how the ground will affect the MIMO performance.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

In this paper, the author proposes a novel modified loop antenna element (MLAE) for 8×8 MIMO arrays in smartphones, offering a wide impedance bandwidth and effective coverage for 5G NR bands and NR-U band n46, optimized through design modifications and parameter tuning. Here are my comments: 1、The introduction section is too much. 2、The physical picture is not clear enough, and it is recommended that the uploaded physical picture be clearer. 3、The phrase "Multi-input Multi-output (MIMO) system" is used multiple times. It's sufficient to define MIMO once and use the acronym thereafter.For example, the Multiple Input Multiple Output (MIMO) in line 29 and line 77, etc. 4、Check the page 2, lines 46-47,"NII-5 (5.925-6.425 GHz), U-NII-6 (6.425–6.525 GHz), U-NII-7 (6.525–6.875 GHz)" use either a hyphen or an en-dash consistently. 5、In line 100, The sentence "In contrast to the IFA-pair design in [50,51] implements an integrated slot antenna pair for 8×8 MIMO operation." is unclear and grammatically incorrect. 6、In line 138 and 142, ensure consistent spacing between units and numbers: "21×6 mm²" should be "21 × 6 mm²." There should be a space after the symbol. 7、Some closely related references are suggested to be added and discussed, e.g., DOI: 10.1109/TAP.2022.3233472, DOI: 10.1109/TAP.2023.3243729, DOI:10.1364/OL.491711, DOI: 10.1103/PhysRevApplied.21.024009.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

There are some problems with the formatting of English papers.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Based on the responses given by the corresponding author, I believe that this research is well-suited for publication in MDPI Electronics.

　The table of comparisons in the prior manuscript illustrates the suggested antenna’s good performance. Nevertheless, a thorough explanation of the antenna performance, such as radiation modes and inconsistent ECC values, was not provided to let readers fully appreciate the significance of this work. The proposed MIMO antenna array has a 6-dB impedance bandwidth, which completely supports 5G NR in the sub-6 GHz spectrum and a less complicated fabrication process.

　Follow-up replies provided by the author are incredibly informative. The latest manuscript addresses the questions raised by reviewers. The most recent revision also includes additional studies, such as the effect of cellphone batteries on antenna performance and throughput of the proposed MIMO antenna array. In the revised text, the operating principle of the MLAE and its contribution are easy to follow. 

Other concern:　Fig.18 (c) is missing. I believe the author mistakenly stated Fig. 18(b) as Fig. 18(c). Please change the sentences in lines 350-355.