A Bra Monitoring System Using a Miniaturized Wearable Ultra-Wideband MIMO Antenna for Breast Cancer Imaging

Round 1

Reviewer 1 Report

The paper has been examined in detail. Overall, this work has been conducted on a well-investigated subject and there are many works proposed in the general area of body-centric and biomedical antenna/EM subsystems. The provided list of references is exhaustive and there are many reductant works cited; it should be amended to only include the primary works in the related areas and those that have been indexed in the Web of Science. Then, these selected works should form a qualitative table, comparing all the aspects and applications of the existing works with the proposed work, including the pros and cons of the current work too. This table should then be added or replaced with Table 5. The quality of the result figures is low and should be replaced with higher resolution ones (preferably in the vector format). The English language and technical writing should be revised thoroughly as well, as the current presentation is not meeting the essential standard.

Author Response

Thank you very much for your comments.
the references were amended
table 6 was added
all the figures were checked and improved
The English writing was rechecked. However, it has been already checked by a native proofreader.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the paper, authors present a wearable antenna system for the breast cancer detection. Antenna elements are based on a planar monopole similarly to [A]. In [A], the system is operated in frequency range from 2 to 4 GHz:

- At higher frequencies, electromagnetic waves are strongly attenuated by living tissues. Therefore, relevant cancer detection systems are operated at frequencies below 10 GHz [B].

- Wearable antennas can be hardly manufactured for the operation at higher frequencies due to a limited manufacturing accuracy. Hence, the operation frequencies above 10 GHz are difficult to be reached [C].

Authors should in detail explain why the frequency range from 5 to 30 GHz was selected for the operation with respect to above facts.

In most cancer detection systems, open-ended coaxial probes are used as antennas. In this case, the radiated energy is strongly focused into the tissue, and the use of the TEM mode provides a reasonable frequency range of operation. And the mutual coupling among probes is negligible. In case of monopoles, a significant portion of energy is radiated into surroundings, characteristics (impedance ones, polarization ones) are rather complicated and mutual coupling is stronger. The presented antenna should be compared with a coaxial probe in detail to demonstrate the advantages.

In the paper, I miss a physical explanation of antenna geometry. According to my experience, similar parameters can be reached by using a properly designed lambda/4 bow-tie monopole. The fabrication of a monopole is simpler because no vias are needed. Authors should explain operation principles of the presented antenna in detail and should provide comparison with a bow-tie monopole. When a physical background is provided, parametric studies can be significantly reduced.

What is the reason for writing Section 3? In cancer detection systems, in-body wave propagation plays the dominant role. Hence, the on- and off-body propagation is not relevant. If horizontally polarized waves are radiated, mutual coupling among antennas is strongly suppressed.

Values of efficiency and gain of the antenna are too high to be realistic. Since the antenna operates in proximity of tissues exhibiting high losses, both efficiency and gain have to be significantly lower. Also, the radiation pattern should be deformed by the tissue [D]. The antenna should be measured in free space and on a realistic phantom to show the influence of the tissue to the efficiency.

The paper has the potential to be published but the manuscript has to be significantly improved.

[References]

[A] E. Porter; H. Bahrami; A. Santorelli et al. A wearable microwave antenna array for time-domain breast tumor screening. IEEE Transactions on Medical Imaging, 2016, vol. 35, no. 6, p. 1501-1509. DOI: 10.1109/TMI.2016.2518489.

[B] M.A. Aldhaeebi; K. Alzoubi; T.S. Almoneef et al. Review of microwaves techniques for breast cancer detection. Sensors, 2020, vol. 20, no. 8, article no. 2390. DOI: 10.3390/s20082390

[C] M. Cupal; Z. Raida; Frequency limits of textile-integrated components. 23rd International Microwave and Radar Conference (MIKON). Warsaw (Poland): IEEE, 2020. DOI: 10.23919/MIKON48703.2020.9253965

[D] K. Pitra; Z. Raida; Miniaturized antenna for body centric communication. European Conference on Antennas and Propagation. Gothenburg (Sweden): IEEE, 2013.

Author Response

Thank you very much for the comment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Authors in article have proposed and demonstrated an UWB antenna with a full GND in order to attain a large BW with consistent radiation properties while keeping the SAR value within a reasonable range for breast cancer imaging. The idea and concept of the paper are interesting, and promising results have been achieved and then experimentally validated. The proposed design validity has been approved by providing a fair comparison with prior and recent arts. The proposed design seems to be attractive for antenna and propagation community. However, prior to final recommendation the paper's organization needs to be improved and the following points should be carefully addressed within the manuscript to improve its quality.

1) In the abstract section, authors have mentioned that "a miniaturised, dual-polarised, multiple input-multiple output 17 (MIMO) wearable antenna is proposed." Please briefly explain its design process in this section.

2) It would be nice to mention the MIMO antenna's spacing in the abstract section.

3) Decoupling methods are very important to design MIMO antenna systems. Therefore, it would be nice to mention some recent decoupling approaches in the introduction section. In below there are proper suggestions.

"Low-Interacted Multiple Antenna Systems Based on Metasurface-Inspired Isolation Approach for MIMO Applications", Arab J Sci Eng (2021). https://doi.org/10.1007/s13369-021-05720-6.

“Wideband linear microstrip array antenna with high efficiency and low side lobe level” Int J RF Microw Comput Aided Eng. 2020;e22412, doi: 10.1002/mmce.22412.

- A Comprehensive Survey on "Various Decoupling Mechanisms with Focus on Metamaterial and Metasurface Principles Applicable to SAR and MIMO Antenna Systems", IEEE Access, vol. 8, pp. 192965-193004, 2020, doi: 10.1109/ACCESS.2020.3032826.

"Miniaturized microstrip patch antenna with high inter‐port isolation for full duplex communication system", doi: 10.1002/mmce.22760.

4) The configuration of the proposed antenna seems to be complex. Please provide some exaltations about this issue?

5) The fabricated layout of the proposed MIMO antenna is not clearly shown in Figs. 2 and 9. Please display the manufactured prototype in a single format.

6) Why the proposed antenna has been implemented on two layers?

7) The feeding mechanism of the antenna should be more elaborated.

8) In table 5 the novelty of the proposed work can be discussed with the following work as.

"Metamaterial-Inspired Antenna Array for Application in Microwave Breast Imaging Systems for Tumor Detection", IEEE Access, vol. 8, pp. 174667-174678, 2020, doi: 10.1109/ACCESS.2020.3025672.

9) I think conclusion is too long. It needs to be summarized. For example, first paragraph of the conclusion is more suitable for the introduction section.

10) In the top side of the antenna as shown in Fig.2(a), we can see two metallization parts without connection with each other. How its work? Please discuss. The coupling feeding mechanism needs to be more discussed.

Author Response

Thank you very much for the comments.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper has been examined, and the main points have been addressed in this revised version. Thus, this manuscript may be accepted upon a final English check.