5.8 GHz High-Efficiency RF–DC Converter Based on Common-Ground Multiple-Stack Structure

Round 1

Reviewer 1 Report

This paper presents a rectifier array works at 5.8 GHz for microwave power transmission with high input power. The theoretical analysis and experimental validations have been properly presented. However, I have the following concerns on this paper which need further justifications.

 

1.    First of all, the selling-point of this paper, as highlighted by the authors, is the common ground arrangement and RF isolation between each rectifier. But, the idea is not new since that the shared ground plane on a single PCB board for rectenna arrays has been heavily investigated. On the other hand, the so-called RF isolation network is also not new and somehow complicated. A simpler method can be realized by using a series inductor.

 

[Ref 1] F. Erkmen, T. S. Almoneef and O. M. Ramahi, "Scalable Electromagnetic Energy Harvesting Using Frequency-Selective Surfaces," in IEEE Transactions on Microwave Theory and Techniques, vol. 66, no. 5, pp. 2433-2441, May 2018.

[Ref 2] T. S. Almoneef, F. Erkmen, M. A. Alotaibi and O. M. Ramahi, "A New Approach to Microwave Rectennas Using Tightly Coupled Antennas," in IEEE Transactions on Antennas and Propagation, vol. 66, no. 4, pp. 1714-1724, April 2018.

 

2.    In Fig. 5 (b), the authors have shown the difference of efficiency when the third harmonic termination stub is used/unused. In the text, the underlying principle of the difference should be studied rather than using simple sentences to summarize the phenomenon.

 

3.    When discussing the input source impedance of the rectifier, please note that such impedance is power-dependent and also load-dependent. The authors should specify the corresponding power and load resistance for all mentioned impedance values.

 

4.    From Fig. 6, the DC-blocking capacitor Cdc is normally placed after the matching network. In addition, this capacitor should be included to the voltage doubler schematic as in Fig. 4.

 

5.    Please study the difference when the Cdc is located in front/behind of the matching circuits.

 

6.    Please replace Fig. 5c by using I-V diagram of the diode junction which is more straightforward.

 

7.    The effect on performance with and without using the RFIN should be shown. As the current structure in the design is frequency-dependent and a bit complicated.

 

8.    The size of the circuit as shown in Fig. 11 is large. Please compare the electrical size of all circuits in Table I.

 

9.    When the rectifier arrays are in series connections, the step rectifiers will have a significant impact on the load impedance of the former rectifier. This work also has alternative RFIN between rectifiers which influence the load as well. Do you have any comments?

 

10.  Please show the results of conversion efficiency vs. load. The recommended range is from 1 to 10k ohms.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

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Comments for author File: Comments.pdf

Author Response

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Reviewer 3 Report

This is a good paper, a 5.8GHz RF-DC converter is proposed and designed. The written of this paper is very good. The system structure is provided, and the detailed circuit is also provided. At last the PCB prototype is presented with the testing platform. The experimental results validate the proposed structure. Here are a few minor suggestions.

1.       Please clarify the contributions of the proposed system at the very beginning. For example, summarize in three bullets. It will help the reader to get the main points faster.

2.       More experiments can be provided. In this submission, there are only two figures provided in  Fig. 13. It is expected to have more experimental results to support this work.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thanks for the response to my comments. Most of them have been addressed. One minor comment is that the dimension in the comparison table should be the electrical size (relative wavelength) since other designs work at different frequencies. 

The authors stated that the circuit size is acceptable after taking the antenna part into account. This is not very accurate since some antennas like dipole and monopole must be detached from the metal ground. 

Author Response

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Author Response File: Author Response.pdf