Application of 3D Virtual Prototyping Technology to the Integration of Wearable Antennas into Fashion Garments

Round 1

Reviewer 1 Report

GENERAL COMMENTS

The manuscript discusses the utility of using clothing industry-related CAD software for seamless integration of wearable antennas into clothing “without compromising the garment elegance or comfort,” as the authors claim in the Abstract.

The manuscript is well structured and written in clear English, with adequate usage of references.

Some figures do not have sufficient resolution or legibility (to be specified below). (I assume that the authors have acquired permission to re-use some figures from the respective copyright owner.)

Although the manuscript brings an informative overview of the clothing design industry relevant software and illustrates attractive usage of it for integration of wearable antennas into the smart clothing, the major objection to this text lies in the fact that the examples shown here do not actually solve anything in practice because antennas are just one (inevitable) component in radio transmission and cannot do anything without other supporting components (e.g. an RF source or load, transmission lines, transmitters/receiver/transceiver, mixer, (de)modulator, or LNA, depending whether it is used in transmit or receive or transmit/receive mode). Once you add some of those, you inevitably compromise the garment elegance or comfort (for now).  

SPECIFIC COMMENTS

Abstract

- point of view however antenna > I suggest to end sentence after view and start a new one with “However…”

Section 1

- Fig. 1 >> I do not think the researchers in [6] ever suggested that patch antenna to be seriously worn like it is presented in Fig. 1, but I will not be their advocate

Section 2

- Fig. 2: the image has a pretty poor resolution. I understand the publication is from 2003, but I remember that in 2003, computers were capable of producing sufficient resolution of images and I hope the quality of this image can be improved.

- Fig. 3 has poor resolution. It is not legible to support the discussion made in the manuscript.

- Fig. 4: same comment as for Fig. 3

- Fig. 6: this figure is of adequate quality, yet the perspective that was used here does not sufficiently present the antenna itself because we see the feed line connected to the edge of the bottom side to some board. Although the argument can be that the detail information can be found in Ref. [12], I also believe the manuscript should have a good level of self-sufficiency with well selected figures.

Section 3

- First paragraph partly contains unusual style such as “the Ph.D. thesis of the first author” and “the 1^st 3D Fashion Summit in Greece (2021 [28] where the first author was head of the steering committee.”  >> we don’t need a CV, just references and necessary comments about them.

ll. 6-7: The part where a series of software is described is too verbose and sounds more suitable for an article intended for some commercial magazine. I think the refereed list on the bottom of page 5 suffices and descriptions of software on pp. 6-7 deleted. At best, each paragraph should be reduced to the most important trait of that software.

Section 4

- Fig. 7: As the reviewer commented out in the first part of the review, the “solution” in Fig. 7 can perhaps impress fashion designers and those that are not familiar with antennas. Antenna engineers understand that the authors’ text pertaining to Fig. 7 are not complete and are thus somewhat misleading. Mere placement of the antenna, albeit being elegantly placed around the bottom of the dress, is just part of the work needed to make the circuit functional and, without other circuitry, it cannot do any meaningful operation for communications. As you can tell from Fig. 5, it is the antenna only, yet to receive FM signals, the complete circuit also requires a cascade of other components: an LNA, a bandpass filter, a mixer, an IF filter, demodulator, a DC source to power the active circuits, and, of course – a speaker to be able to listen to FM radio! Although we understand some of these components may occupy a fairly small volume and even come within an integrated circuit, they still must be accounted for within that dress before you make a pitch about ‘not compromising garment elegance and comfort.’ Furthermore, how will the wearer listen to that FM? If that will be by a Bluetooth headset, then, in addition to the aforementioned components, we also need a Bluetooth transmitter to send the baseband information to the Bluetooth headset.

Now, when you integrate these components, how will we protect them during washing cycle?

Furthermore, there is a possible issue with the antenna operation as the authors presented in Fig. 7. for the following reasons:

a) notice that the original antenna in Fig. 5 contains dipoles laid out on a rectangular plane, while the authors here used them bent nearly in a circular shape. The geometry is very important for the antenna operation and in this case, the Authors bent the antenna geometry quite a bit. We can even state that we now deal with a loop antenna and loop antenna, depending on the ratio of its parameters, can work in radial or axial mode of radiation. The reviewer cannot bargain right now which of these effects may kick in and how strong, but these things should in fact be checked by electromagnetic modeling and simulation to check the radiation pattern (and gain).

b) Notice that unlike in the original antenna in Fig. 5, which has fixed size and geometry, the antenna as the Authors proposed it in Fig. 7, will often bend, twist and change its form in a variety of ways as the dress will move around the body during the walk or when the lady sits down and/or crosses her legs etc. Such antenna form changes are also a challenging point which calls for caution and better analysis when proposing such a design.

The Reviewer guesses that the manuscript was mostly driven by the Author 1 and his excitement about integrating the antenna in a visually appealing and aesthetic way, which is everybody’s goal, but there should be more caution and input from Author 2 in terms of some rules that should be obeyed when designing a successful antenna.

- Figs. 8-13 pretty much get the same comment as above, with some extra observations that can be mentioned for, e.g. Fig. 9: most of the back is covered by the antenna surface. So, again: after we add chips that are needed for the antenna to do its job, will it still be a seamless integration, without scratching the wearer’s back? What about these chips when it comes time to wash the shirt? In this case, it is also advisable that SAR be checked due to the operation at a relatively low frequency.

Section 5

- referring to line 4 of Sec. 5 that virtual prototyping tools “offer a full library of fabric materials with all their physical characteristics being fully parametric.”, the Reviewer would  like to hear/see whether they also offer information about (di)electric properties of the fabrics in the library.

Could the Authors list and show what electric parameters are associated with each fabric from that library, because that is something helpful and important for an antenna designer?

- Please mention/refer to a few competitive “hardware tools involving material scanning technologies” that you have in mind.

Section 6

This reviewer does not quite agree with the tone the Authors give to their discussion in a way that “Pure engineering design…focuses on electromagnetic efficiency of the antenna, but neglects the aesthetic dimension of a garment.”

>>> Antennas must obey some design rules and are not just an aesthetically laid out wire over the fabric. That is, unfortunately, one limiting factor. Another one is the already mentioned one: without some other components, an antenna is just a useless structure. Once we add all the necessary components, the seamless integration, aesthetics, and comfort get seriously challenged or compromised (until we perhaps see the day when nano-size electronics will do the rest of the job and we will then primarily be focused with the antenna integration).

So, just as the previous works did not offer a complete solution, but merely prototypes of some sort of wearable antenna, this manuscript also does not offer nearly a complete solution, plus it introduces dubiousness about the validity of some designs. To design a successful antenna, engineers must check and satisfy various “efficiency” parameters that fashion industry designers are not aware of.

This manuscript is positive if giving a message that a synergy between fashion designers and antenna/electronics engineers is the best approach in search of the ultimate solution.

Right now, although looking more appealing than previously published works, designs proposed here offer dysfunctional antennas because the work in this manuscript merely embedded various antennas in the garment without providing a clue how the signal would be feed in/from the antenna and discussing any other necessary circuitry that also must be embedded for any real application to work.

References

- Please insert the full name of the URL source in references 29 to 35.

SUMMARY OF THE REVIEW

After reading it a couple of times, this reviewer has a mixed emotions about this manuscript. On the one hand, it is welcome to see how some modern cloth-design CAD tools are utilized to integrate antenna into garment as part of a sophisticated 3D simulation and to prepare a visually appealing look of the garment.

On the other hand, the examples proposed here have not been checked to be valid from the electromagnetic point of view and raise various doubts about the functionality of at least some of these cases. It is not enough to propose just an aesthetic vision of a device that is possibly dysfunctional and pointless.

Now, just as various earlier works, that the Authors referenced, did not pay enough attention to aesthetic aspect of the integration, but were at a stage of a laboratory prototypes, the designs proposed here presented merely the aesthetic aspect of it, without really having functional antennas because:

a) the authors did not check the operation of the antenna in Fig. 7 or SAR in Fig. 9, to mention two cases

b) the authors integrated only the antenna into the garment, without any other necessary circuitry. And without other components, antenna is useless.

In this reviewers opinion, this manuscript requires a major revision taking into account the benevolent comments and discussion indicated within the review and also  include some moderation about the designs offered here until the Authors are able to integrate all the necessary components into the garment ‘without compromising the garment elegance or comfort.’

We all look forward to that day to come!

Thanks!

Author Response

Reviewer 1:

The reviewer‟s major concern can be summarized as follows: “just as the previous works did not offer a complete solution, but merely prototypes of some sort of wearable antenna, this manuscript also does not offer nearly a complete solution” and “the authors integrated only the antenna into the garment, without any other necessary circuitry…the complete circuit also requires a cascade of other components: an LNA, a bandpass filter, a mixer, an IF filter, demodulator, a DC source to power the active circuits, and, of course – a speaker to be able to listen to FM radio. Once you add some of those, you inevitably compromise the garment elegance or comfort”.

The reviewer is absolutely right in a sense that our manuscript neither offers a new antenna solution nor does it propose the design of a complete communications system integrated to a dress. However, this is not the purpose of the paper. Instead, we opted to focus on a few antenna designs in the literature, which have obviously been tested already with respect to their functionality, prior to publication, and demonstrated how 3D Virtual Prototyping Technology can be used to integrate these antenna into actual clothes that can be worn in real life. In other words, the paper‟s aim is exactly pinpointed by the reviewer‟s hypothesis: “This manuscript is positive if giving a message that a synergy between fashion designers and antenna/electronics engineers is the best approach in search of the ultimate solution”.

Moreover, we restricted our work to the antenna only, and not to the complete supporting circuitry, which is commonplace in thousands of papers published on antennas. It would have been way too ambitious otherwise. Nevertheless, we welcome the reviewer‟s suggestions and implement them when feasible, that is why we have completely revised Sections 2 and 4, now integrating a feeding network along with the antenna main body. The dimensions of this particular network, again originally published elsewhere, are so small that the device can be completely inserted into the lining, without “inevitably compromising the garment elegance or comfort” or possibly “scratching the wearer‟s back” as the reviewer claims.

Other points made by the reviewer:

1. “Abstract- point of view however antenna > I suggest to end sentence after view and start a new one with “However”. Modified as suggested.

2. “Fig. 2: the image has a pretty poor resolution.” The image has been redrawn from scratch.

3. “Figs. 3 and 4 have poor resolution.” Both figures have been replaced by others, depicting a completely different antenna to be integrated into a dress in Section 4.

4. “Fig. 6: the perspective that was used here does not sufficiently present the antenna itself because we see the feed line connected to the edge of the bottom side to some board. Although the argument can be that the detail information can be found in Ref. [12], I also believe the manuscript should have a good level of self-sufficiency with well selected figures.” A more descriptive figure taken from [12] was added.

5. “Section 3, First paragraph partly contains unusual style.” Paragraph has been rephrased.

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6. “Section 3, ll. 6-7: The part where a series of software is described is too verbose.” This part is has been shortened considerably, including the most important trait of each software, like the reviewer recommends.

7. “Fig. 7: the original antenna in Fig.5 contains dipoles laid out on a rectangular plane, while the authors here used them bent nearly in a circular shape.” In the revised version a completely different antenna has been treated, along with its feeding network. This particular configuration is not prone to bending or twisting, and therefore there is no need for extra electromagnetic simulation to evaluate deformation effects.

8. “Section 5, referring to line 4 of Sec. 5 that virtual prototyping tools “offer a full library of fabric materials with all their physical characteristics being fully parametric”, the Reviewer would like to hear/see whether they also offer information about (di)electric properties of the fabrics in the library. Could the Authors list and show what electric parameters are associated with each fabric from that library, because that is something helpful and important for an antenna designer?” We have added the following information: “Virtual prototyping tools for typical garment visualization do not include woven fabrics with inserted metallic yarns or with plasma coating in their default libraries. Understandably enough, electromagnetic properties of the various fabrics are not explicitly shown in the menu, since prototyping software was not originally intended for electromagnetic simulations. However, the user can create new libraries, especially for highly conductive materials, or for dielectrics with specific permittivity, after importing them via specialized hardware tools involving material scanning technologies or applications with embedded AI technologies.”

9. “Please mention/refer to a few competitive “hardware tools involving material scanning technologies” that you have in mind.” We have added the following information: “Examples of these devices are xTex by Vizoo [43] for scanning physically based samples of up to A4 paper size and Scanatic™ Nuno Fabric Scanner [44], as a more affordable solution for a speedy material scanning.”

10. “References: Please insert the full name of the URL source in references 29 to 35.” Done.

11. “…also include some moderation about the designs offered here until the Authors are able to integrate all the necessary components into the garment „without compromising the garment elegance or comfort. The authors‟ comment on elegance or comfort has been moderated in the abstract: “wearable antennas have been incorporated in an automated manner, reducing the chances of compromising the garment elegance or comfort.”

Reviewer 2 Report

Overall, a good initiative from the authors.  Fashion might be the least concern for antenna design, as making sure the design works becomes the priority.  To make sure the paper has a good technical point, please refer comment below:
1) The author claims..." realistic clothing design procedures will be presented", however, no detailed procedure discuss in the paper. 
2) Should discuss more on the chosen antenna in both technical & physical appearance
3) fashion design simulator  - should discuss more on what the simulator is capable of...aside from the 3D view, what kind of result this simulator can provide? Does the 3D model can be transferred to another simulator such as CST so that can have a detailed simulation
4) Consideration on how the antenna works should be included when embedded into cloth, power location, how this can be connected to the devices, etc
5) How does this help in antenna design? What are the key parameters or results that can be captured using the simulator?
6) There is a lot of research on compact wearable antenna which is more suitable to be embedded into cloth

7) Improve the conclusion and highlight why this important in this field

Comments for author File: Comments.pdf

Author Response

Reviewer 2:

1. “The author claims..." realistic clothing design procedures will be presented", however, no detailed procedure discuss in the paper.” Response: An 8-step procedure is now described in the second paragraph of Section 4.

2. “Should discuss more on the chosen antenna in both technical & physical appearance.”

Response: More detailed description of the new antenna and the feeding network in Section 2.

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3. “Fashion design simulator - should discuss more on what the simulator is capable of...aside from the 3D view, what kind of result this simulator can provide? Does the 3D model can be transferred to another simulator such as CST so that can have a detailed simulation.”

Response: The following information was added to the second paragraph of Section 4: “The output file obviously contains implicitly all information related to the fabric mechanical and electromagnetic parameters of the materials involved in the design. Furthermore, it can be extracted in various formats, including .obj, meaning that it may be imported as input to widely used electromagnetic simulation software tools, such as CST EM Studio.”

4. “Consideration on how the antenna works should be included when embedded into cloth, power location, how this can be connected to the devices, etc.”

Response: We have added description of a feeding network for the new antenna in Section 2. All antennas described have already been tested for performance in their original publications. Complete simulations of the entire garment worn by an avatar will be the focus of future research.

5. “How does this help in antenna design? What are the key parameters or results that can be captured using the simulator?”

Response: The following information was added to the second paragraph of Section 4: “The output file obviously contains implicitly all information related to the fabric mechanical and electromagnetic parameters of the materials involved in the design.”

6. “There is a lot of research on compact wearable antenna which is more suitable to be embedded into cloth.”

Response: Indeed, a completely new antenna and the feeding network are described and integrated in Sections 2 and 4.

7. “Improve the conclusion and highlight why this important in this field.”

Response: The conclusion was extended significantly and the importance of the paper was highlighted.

Round 2

Reviewer 1 Report

GENERAL

It is evident that reviewer’s recommendations and questions have been addresses in the revised version. Nonetheless, there are still aspects the reviewer wants to comment related to the current versio of the manuscript. Although it is in the eyes of the beholder, this text sounds to the reviewer as: “Before us, those antenna researchers made some ugly antennas and cared merely about the antenna performance and nothing about the esthetics. Now, we took care of everything using some Fashion CADs and now it looks beautiful.” So, most of the following comments will go in that sense.

SPECIFIC

Fig. 2: it can be noticed it was improved, but there are still some „awkward-looking“ details such as:

- shading of the sides does not contribute much to the figure, especially in light of the fact that the lines that should not be visible under this perspective, are actually visible

- the patch is drawn as being on the bottom side of the substrate, while it should be on the top side

Figs. 4 and 6: these two figures provide the fact that the Authors seem to overlook or neglect throughout the manuscript: the feeding cable that one needs to feed the RF signal to the antenna. And that RF cable comes from some RF generator… So, both the feeding cable and the RF source have to be embedded somewhere within the garment. I understand that the earlier papers did not have it, too, but they were primarily focused on the antenna design and did not make a pitch about the elegance.

p.5: „By using digital prototyping tools…design of such wearable items…developed in a very fast and efficient manner…“ >> the Reviewer finds this to be a bit too bold a statement in this context, for the reasons discussed earlier by the Reviewer. The fashion design software cannot simulate electromagnetic performance that always matters. The former can be good for presentations to wide audience and at fashion shows, but they cannot include all it takes to build a working prototype, let alone a commercial-grade product.

p.6: Optitex3D

„Pattern Design Software (PDS)“ – why this name when the title is Optitex3D and the authors referred to it as Optitex3D in the first version of the manuscript?

- „an ingrate digital fabric“ >> integrated

p.7: „…obviously contains implicitly all information related to the fabric mechanical and electromagnetic parameters of the …“ >>> what is the meaning of the phrase „obiously contains implicitly all…“

p.7. „In Fig. 7 the patch antenna…complete with its feeding network >> where is the feeding network shown? It seems that the Authors refer to the antenna port as the feeding network, but it is not unequivocal term because feeding network often refers to the layout that distributes power to the antenna  array elements and we do not see it in these subfigures even though Figs. 7G and 7H imply we are looking at a 2x2 array.

- all-over print is nice, but it's just trying to neglect the true challenge here. What about the feeding cable placement, transmitter and/or receiver placement etc.

When a reader looks at this, a spontaneous question is being raised: where is the „complete“ feeding network shown?

Where it the cable feeding the signal to the antenna?

How will we actually test the operation of this antenna or array?

p.12: on the Conclusions

The Authors integrated more like antenna layouts into the fabric or dead antennas, rather than functional antennas.

- „by miniature feeding network“ – the Authors refer to the antenna port, but they overlook that the port must be fed power by some feeding cable  that comes from some RF generator, none of which is accounted for in this manuscript.

- „offers an opportunity for antenna simulation in the presence of real-life garments.“ – what simulation do the Authors refer to exactly? Namely, these fashion-minded CADs cannot do EM simulations. Some EM-minded CADs can, also offering physical models of human body yet without a garment.

- „the entire development is completely digital…“ – sooner or later, the developer has to make a real prototype, test antenna operation… and that does not seem to be accounted for in this paper

Thanks!

Reviewer 2 Report

Overall, the authors have done some improvements based on previous comments.

1. Please rephrase the sentence in the 1st paragraph  "On the other hand, flexible antennas are by definition much easier to wear since neither human bodies or clothes are usually stiff, however they are much more difficult to incorporate to a garment." - it is difficult to understand what the authors want to present here.
2. Do make sure the figures are clear 
3. In Figure 7, the antenna is located at the end/bottom dress, in which the user might sit on it or the clothes will crumple the most. What are the criteria considered? Any justification? Feed location? Pleasant to the eyes, but what about its functionality

Author Response

Response to reviewers:

We would like to express our appreciation to both reviewers, whose constructive criticism was crucial in the significant improvement of the paper. Our response to the reviewers’ comments (in red) is attached below: ____________________________________________________________________________________________________

1) Please rephrase the sentence in the first paragraph: “On the other hand, flexible antennas are by definition much easier to wear since neither human bodies or clothes are usually stiff, however they are much more difficult to incorporate to a garment.” It is difficult to understand what the authors want to present here.

The sentence has been rephrased as follows: “On the other hand, flexible antennas can easily be worn by a human body, which naturally moves, causing clothing deformation, however such radiating structures are much more difficult to incorporate to a garment.”

2) Do make sure the figures are clear

All figures produced by us are of the best possible resolution. Although this is not necessarily true for figures borrowed by other papers in literature, we tried our best to improve their appearance.

3) In Figure 7 the antenna is located at the end bottom dress, in which the user might sit on it or the clothes will crumple the most. What are the criteria considered? Any justification? Feed location? Pleasant to the eyes, but what about its functionality?

We have added the following paragraph with clarifications: “Of course, placement of the antennas at that particular position of the dress is only indicative of the capabilities of the prototyping technology utilized. Depending on the actual radiation requirements the antennas may be equally incorporated to any location, provided that there is enough space, for example on the chest or the back, where deformation due to crumpling would be minimal.”