Steer by Image Technology for Intelligent Reflecting Surface Based on Reconfigurable Metasurface with Photodiodes as Tunable Elements

Round 1

Reviewer 1 Report

This paper presents a reconfigurable metasurface technology based on photodiode. This is a topic of considerable interest to people in related fields. Compared with the traditional reconfigurable hypersurface, its design is simple and saves the complex circuit design. The simulation effect is good at the unit level of 2.4GHz. Detailed comments are as follows:
1）In this paper, the effect of cell level simulation is good. Is there an array level physical processing verification effect?
2）The picture font needs small adjustments. For example, the fonts of 'a', 'b' and 'c' in Figures 9 and 12.

Author Response

Ms. Ploy Assavajamroon
Assistant Editor of CRYSTALS

 

Manuscript ID: crystals-1559360

Type of manuscript: Article

Title: Steer by Image Technology for Intelligent Reflecting Surface based on
Reconfigurable Metasurface beyond 5G communication

Authors: Daniel Rozban *, Amir Abramovich *, David Rotshild, Efi Rahamim,
Asaf Barom, Rotem Yosef, Liel Bhanam

 

Dear editor,

We would like to thank the reviewers for their constructive remarks regarding manuscript ID: crystals -1559360. The authors would like to mention that this paper presents new technology for controlling Intelligent Reflecting Surface (IRS).

The new technology called Steer by image (SBI) is based on projecting an image to the backside of an IRS rather than connecting it to hundredths or more DC sources and complicated FPGA board as done today (we call it Steer By Wire (SBW) technology). The use of SBI technology will significantly simplify the design and manufacturing process compared to nowadays SBW technology.

Since SBI is a new idea and new technology, no demonstration of such can be found in the literature. Nevertheless, using off the shelf-component, literature, and some innovations of our research group, we were able to design and simulate an IRS operating in WI-FI which is based on SBI technology.

I would like to emphasize the main goal of this paper is to present the SBI technology and to describe its advantageous compared to the well-known technologies used today (SBW). The authors hope that you will find our manuscript, crystals-1559360 suitable for publication in your journal.

 

The authors addressed all the reviewer's remarks, comments, and suggestions. Following, please find a detailed description of the author's response to the reviewer's requests.

 

Reviewer  1:

This paper presents a reconfigurable metasurface technology based on a photodiode. This is a topic of considerable interest to people in related fields. Compared with the traditional reconfigurable hypersurface, its design is simple and saves the complex circuit design. The simulation effect is good at the unit level of 2.4GHz. Detailed comments are as follows:
1）In this paper, the effect of cell-level simulation is good. Is there an array-level physical processing verification effect?

The unit cell was redesigned. The new design considered the possible values ​​of the photodiode capacitance, which allows capacities in the range of 4pF to 12pF. In addition, a far-field simulation of a 5X80 array was carried out showing radiation steering at an angle of about 26 degrees with good agreement with the theory
2）The picture font needs small adjustments. For example, the fonts of 'a', 'b', and 'c' in Figures 9 and 12.

The fonts in figures 9 and 12 were fixed accordingly

 

Reviewer 2 Report

This Reviewer believes that the actual contribution of the Authors is marginal with respect to the content of this work. More than a half of the manuscript reports results from other papers, and only in the last pages some preliminary results are shown.

In general, the overall contribution of this work seems very limited. In addition, there are a plenty of flaws, imprecise statements, typos, and language issues that makes this submission unsuitable for publication.  Just to give but a few examples. The title includes the word '5G' and results are reported from 0 to 4 GHz. Maybe the Authors should check which frequencies 5G is actually targeting. The Authors also write that traditional metasurfaces are complicate circuits, whereas at microwave frequencies can even be realized in PCB technology with simple patterning on commercial laminates, e.g., a 2-D array of subwavelength metallic square patches on top of  an FR-4 substrate. There are no keywords for this manuscript, the affiliations of all the Authors are missing, 'Veselago' is wrongly spelled, etc., etc..

In the Reviewer's opinion the manuscript should be rejected.

Author Response

Ms. Ploy Assavajamroon
Assistant Editor of CRYSTALS

 

Manuscript ID: crystals-1559360

Type of manuscript: Article

Title: Steer by Image Technology for Intelligent Reflecting Surface based on
Reconfigurable Metasurface beyond 5G communication

Authors: Daniel Rozban *, Amir Abramovich *, David Rotshild, Efi Rahamim,
Asaf Barom, Rotem Yosef, Liel Bhanam

 

Dear editor,

We would like to thank the reviewers for their constructive remarks regarding manuscript ID: crystals -1559360. The authors would like to mention that this paper presents new technology for controlling Intelligent Reflecting Surface (IRS).

The new technology called Steer by image (SBI) is based on projecting an image to the back side of an IRS rather than connecting it to hundredths or more DC sources and complicated FPGA board as done today (we call it Steer By Wire (SBW) technology).. The use of SBI technology will significantly simplify the design and manufacturing process compared to nowadays SBW technology.

Since SBI is new idea and new technology, no demonstration of such can be found in the literature. Nevertheless, using off the shelf-component, literature and some innovations of our research group, we were able to design and simulate an IRS operating in WI-FI which is based on SBI technology.

I would like to emphasize the main goal of this paper is to present the SBI technology and to describe its advantageous compared to the well-known technologies used today (SBW). The authors hope that you will find our manuscript, crystals-1559360 suitable for publication in your journal.

 

The authors addressed all the reviewer's remarks, comments and suggestions. Following, please find a detailed description of the authors response to the reviewers requests.

 

Reviewer 2:

This Reviewer believes that the actual contribution of the Authors is marginal with respect to the content of this work. More than a half of the manuscript reports results from other papers, and only in the last pages some preliminary results are shown.

In general, the overall contribution of this work seems very limited. In addition, there are a plenty of flaws, imprecise statements, typos, and language issues that makes this submission unsuitable for publication.  Just to give but a few examples.

The title includes the word '5G' and results are reported from 0 to 4 GHz. Maybe the Authors should check which frequencies 5G is actually targeting.

The frequency bands for 5G networks come in two sets. Frequency range 1 (FR1) is from 450 MHz to 6 GHz, which includes the LTE frequency range. Frequency range 2 (FR2) is from 24.25 GHz to 52.6 GHz. The sub-6 GHz range is known as FR1 and the MMW spectrum is known as FR2.

We changed the title of the manuscript to avoid misunderstanding. The new title is:

"Steer by Image Technology for Intelligent Reflecting Surface based on Reconfigurable Metasurface and photodiodes as tunable elements".

The unit cell was redesigned. The new design considered the possible values ​​of the photodiode capacitance, which allows capacities in the range of 4pF to 12pF. In addition, a far field simulation of a 5X80 array was carried out showing radiation steering at an angle of about 26 degrees.

The technology concept shown in this manuscript is shown to be suited for Frequency range FR1 of the 5^th generation of cellular communication depending on the capacitance of the photodiode.

In addition, we note that the proposed technology will be able to work at higher frequencies (Frequency range 2) given a suitable photodiode that allows for smaller capacitances than the photodiode proposed here. The data sheets of the diode proposed here showed capacitance values ​​depending on the intensity of the light impinging on it. Unfortunately, data sheets of other photodiodes do not display the capacitance data as a function of the intensity of the light impinging them.

We are currently working on measurement circuits that will allow us to better evaluate the capacitance of photodiodes as a function of light impinging them.

The authors also write that traditional metasurfaces are complicated circuits, whereas at microwave frequencies can even be realized in PCB technology with simple patterning on commercial laminates, e.g., a 2-D array of subwavelength metallic square patches on top of an FR-4 substrate.

Traditional meta-surfaces require the use of a large number of A / D cards (steer by wire technology). In the design presented in this article, we have shown simulation results for a surface with 5X80 cells. The simulation performed is very heavy and consumes a huge amount of computer time. In practice we expect the metasurface to contain 80X80 cells. For the cell to be able to operate in the traditional way, 6400 different analog outputs are required from the FPGA board, so it is a very complex and very impractical circuit.

The SBI technology,  proposed here solves this problem by projecting an image on the photodiodes located on the backside of the metasurface.

There are no keywords for this manuscript, the affiliations of all the Authors are missing, 'Veselago' is wrongly spelled, etc., etc.

We added keywords to the paper.

In the Reviewer's opinion, the manuscript should be rejected.

We hope the recent changes we have made to this article will allow you to reconsider publishing this article.

Reviewer 3 Report

The authors proposed a reconfigurable metasurface for beam-steering based on Steer by Image technology in the x-band, which is a new strategy to realize beam-steering metasurface. Comparing to the method of Varactor diode or PIN diode, SBI technology has the main advantage of avoiding complex wiring of DC biasing. However, this study has been conducted so roughly and insufficient results of calculation couldn’t demonstrate the design convincingly. Apart from this major issue, the manuscript is poorly prepared: unfocused, format inconsistent, and typos everywhere, which make this work not convincing further. This manuscript couldn’t be accepted for publication unless these major issues have been carefully addressed.

 

1. This study has been conducted roughly. It’s suggested to give more simulated results and analysis about the proposed design, some specific suggestions are listed.

1.1 The simulation setup should be giving in the manuscript. How the photodiode and metasurface array are modeled.

1.2 The beam-steering results and the far-field distributions should be given and analyzed.

1.3 The performance of photodiode should be analyzed in details, and compare with PIN and Varactor diode, such as efficiency.

1.4 The experimental feasibility should be at least explained.

 

2. The manuscript is poorly prepared.

2.1 The background of this work has been excessively stated. These contents might be cited as reference. It’s suggested to rewrite the introduction making it compact, focused, and highlighting the novelty and significance, potential applications in 5G communications.

2.2 The format of equation 1 and 2 is different, and the legend of equations should be reformed in line 147, like Amn, αmn. The font of letter “X” should be carefully chosen. The sequence number of equation 2 is misplaced. In equation 1, “360” should be “360°” or “2π”.

2.3 The quality of the figures should be carefully improved. The format of the references should be checked.

2.4 Other typos like,

      degrees such as “15 °”、“30 °” in lines 91 and other lines are wrong;

      “phasa” in Fig. 14 should be “Phase”;

capital letter in line 359;

“has” should be “have” in line 54;

“addresses” should be “address” in line 58;

The authors should carefully check the typos.

Author Response

Ms. Ploy Assavajamroon
Assistant Editor of CRYSTALS

 

Manuscript ID: crystals-1559360

Type of manuscript: Article

Title: Steer by Image Technology for Intelligent Reflecting Surface based on
Reconfigurable Metasurface beyond 5G communication

Authors: Daniel Rozban *, Amir Abramovich *, David Rotshild, Efi Rahamim,
Asaf Barom, Rotem Yosef, Liel Bhanam

 

Dear editor,

We would like to thank the reviewers for their constructive remarks regarding manuscript ID: crystals -1559360. The authors would like to mention that this paper presents new technology for controlling Intelligent Reflecting Surface (IRS).

The new technology called Steer by image (SBI) is based on projecting an image to the backside of an IRS rather than connecting it to hundredths or more DC sources and complicated FPGA board as done today (we call it Steer By Wire (SBW) technology). The use of SBI technology will significantly simplify the design and manufacturing process compared to nowadays SBW technology.

Since SBI is a new idea and new technology, no demonstration of such can be found in the literature. Nevertheless, using off the shelf-component, literature, and some innovations of our research group, we were able to design and simulate an IRS operating in WI-FI which is based on SBI technology.

I would like to emphasize the main goal of this paper is to present the SBI technology and to describe its advantageous compared to the well-known technologies used today (SBW). The authors hope that you will find our manuscript, crystals-1559360 suitable for publication in your journal.

 

The authors addressed all the reviewer's remarks, comments, and suggestions. Following, please find a detailed description of the author's response to the reviewer's requests.

 

Reviewer 3:

the authors proposed a reconfigurable metasurface for beam-steering based on Steer by Image technology in the x-band, which is a new strategy to realize beam-steering metasurface. Comparing to the method of Varactor diode or PIN diode, SBI technology has the main advantage of avoiding complex wiring of DC biasing. However, this study has been conducted so roughly and insufficient results of calculation couldn’t demonstrate the design convincingly. Apart from this major issue, the manuscript is poorly prepared: unfocused, format inconsistent, and typos everywhere, which make this work not convincing further. This manuscript couldn’t be accepted for publication unless these major issues have been carefully addressed.

 

1. This study has been conducted roughly. It’s suggested to give more simulated results and analysis about the proposed design, some specific suggestions are listed.

 

The unit cell was redesigned. The new design took into account the possible values ​​of the photodiode capacitance, which allows capacities in the range of 4pF to 12pF. In addition, a far-field simulation of a 5X80 array was carried out showing radiation steering at an angle of about 26 degrees in good agreement with the theory. Our recent simulation results showed proof of full feasibility for the proposed technology.

• The simulation setup should be given in the manuscript. How the photodiode and metasurface array are modeled.

The design of the unit cell is given in fig 12. We added the dimensions of the metasurface to Fig.12 b. The simulation parameters are given in Table 1 and Table 2. The photodiode is modeled in figure 8 for a given reverse voltage (zero voltage in a possibility).

• The beam-steering results and the far-field distributions should be given and analyzed.

 

a far-field simulation of a 5X80 array was carried out showing radiation steering at an angle of about 26 degrees. Our recent simulation results showed proof of full feasibility for the proposed technology.

1.3 The performance of photodiode should be analyzed in detail, and compare with PIN and Varactor diode, such as efficiency.

The capacitance of the photodiodes depends on the light intensity that incident on them and is given in Figure 8. Unfortunately, the diode proposed here is the only one whose data sheets show a graph like the one shown in Figure 8.

There are additional photodiodes that allow for smaller capacitance enabling higher working frequency and yet their datasheets do not have the required information for proper simulation.

We are working on circuits that will allow us to measure the change in capacitance depending on the incident light intensity.

 

1.4 The experimental feasibility should be at least explained.

The new simulation results include a redesign of the unit cell. In addition, we showed a shift of about 26 degrees in the far-field. The results of the simulation show proof of full feasibility of the proposed technology

1. The manuscript is poorly prepared.

2.1 The background of this work has been excessively stated. These contents might be cited as reference. It’s suggested to rewrite the introduction making it compact, focused, and highlighting the novelty and significance, potential applications in 5G communications.

The background presented in the introduction to the article is intended to show the possibilities of using the proposed technology. This technology can provide a solution for any of the technologies presented in the background of this article so it was important for us to highlight those different technologies in the background of the article

2.2 The format of equation 1 and 2 is different, and the legend of equations should be reformed in line 147, like Amn, αmn. The font of letter “X” should be carefully chosen. The sequence number of equation 2 is misplaced. In equation 1, “360” should be “360°” or “2π”.

The format of equation 2 was fixed. the legends were reformed. The sequence number of equation 2 was fixed. In equation 1, “360” was changed to “360°”.

2.3 The quality of the figures should be carefully improved. The format of the references should be checked.

We improved the figures in the article and especially we improved Figure 12.

2.4 Other typos like,

      degrees such as “15 °”、“30 °” in lines 91 and other lines are wrong;

line 91 was fixed as required.

 

      “phasa” in Fig. 14 should be “Phase”;

“phasa” was changed to “Phase”; in Fig.14

capital letter in line 359;

the change was made to line 359.

“has” should be “have” in line 54;

The change was made to line 54.

“addresses” should be “address” in line 58;

“addresses” was changed to “address”

The authors should carefully check the typos.

We checked typos and corrected them accordingly.

 

Round 2

Reviewer 2 Report

The Reviewer understands that the novelty is in the use of photo pin diodes instead of other tunable elements to avoid wiring connections needed to biasing lines.

However, the Reviewer here repeats the same comment of the previous round. More than half of the content of the revised version (as per the original manuscript) reports results from other papers and only in the last pages some preliminary results are shown. 

As already raised in the first round, the study is too preliminary and still not mature for publication.  A thorough investigation or even better an experiment would be needed to corroborate the claimed effectiveness of this approach.

Author Response

The manuscript was extensively revised and new simulations results were added. The introduction was shortened and instead, we added references. Simulation results of beam steering were added to this paper showing 1D and 2D beam steering at the frequency of 1GHz. Those simulation results took into account the capacitance-voltage characteristics of the photodiode of AMS OSRAM SFH2704 which is similar to Vishay Semiconductors BVP10.

Other photodiodes can also be used for the SBI technology, however, only the BVP10 has a published capacitance-voltage characteristic as shown in Fig.3 of this paper. We claim that an SBI designed for higher beam frequencies can also be achieved. This will require a lower capacitance of the photodiodes.

We changed the operation frequency of the SBI to 1GHz to achieve beam steering for the capacitance range of the photodiode which is from 4.5 PF to 12 PF.

We hope you will find this revised manuscript suitable for publication.

Thanks

Best regards

Dr. Daniel Rozban.

Reviewer 3 Report

Most of my concerns have been properly addressed except a major one on the introduction and the novelty. I believe that the concept of SBI (Steer By Image) technology has been demonstrated, for example, in Ref [1] and [2]. Therefore, I recommend the authors, again, to reorganize the Introduction part, which includes Sections 1 and 2, and restate the novelty of this manuscript comparing with the highly relevant references.

 

[1] Zhang, Xin Ge, et al. "An optically driven digital metasurface for programming electromagnetic functions." Nature Electronics 3.3 (2020): 165-171.

[2] Zhang, Xin Ge, et al. "Light-controllable digital coding metasurfaces." Advanced Science 5.11 (2018): 1801028.

Author Response

The manuscript was extensively revised and new simulations results were added. The introduction was shortened and instead, we added references. Simulation results of beam steering were added to this paper showing 1D and 2D beam steering at the frequency of 1GHz. Those simulation results took into account the capacitance-voltage characteristics of the photodiode of AMS OSRAM SFH2704 which is similar to Vishay Semiconductors BVP10.

Other photodiodes can also be used for the SBI technology, however, only the BVP10 has a published capacitance-voltage characteristic as shown in Fig.3 of this paper. We claim that an SBI designed for higher beam frequencies can also be achieved. This will require a lower capacitance of the photodiodes.

In the introduction, we added a comparison of the SBI technology to that of Zhang, Xin Ge, et al.

In Zhang, Xin Ge, et al papers it is shown that by remotely changing the illumination light intensity of the photodiodes, the voltage generated by those photodiodes can be dynamically controlled and therefore be used for biasing of the MS tunable elements, that is, in that case, a varactor.

In our paper, the photodiodes are used directly as the tunable MS elements, therefore our concept further simplifies the concept made by Zhang, Xin Ge, et al.

We changed the operation frequency of the SBI to 1GHz to achieve beam steering for the capacitance range of the photodiode which is from 4.5 PF to 12 PF.

We hope you will find this revised manuscript suitable for publication.

Thanks

Best regards

Dr. Daniel rozban.