A Ka-Band Cylindrical Paneled Reflectarray Antenna

Round 1

Reviewer 1 Report

In this article, a work on parabolic reflectarrays is presented. It comprises the design and simulation of an antennas as well as the manufacture and measurement of a demonstrator. The concept is quite interesting but several issues should be addressed in the opinion of this reviewer prior to considering the publication of the manuscript:

1.       The authors claim that SatCom is a potential application of this antenna but they do not propose any particular application. Is the antenna on board or on the Earth? Why is this antenna suitable for this application and what are the advantages of this technology for it?

2.       The reference [14] is the baseline of this work but it is not accessible for now. They should provide it with the submission since the titles are partially similar and this could be important for a proper review of this manuscript.

3.       The designing principle is not discussed in detail and this is the core of the paper. For example, they do not explain in detail the equations (1) and (2) and this is important for the full understanding of the paper. I recommend to extend section 2.

4.       In figure 2 a full 360 cycle of phase shift is not obtained and usually this is a limitation in the design of reflectarray antennas. Please, explain in detail. In addition, a legend should be added to the figure.

5.       The authors claim that the antenna is designed to work in the frequency band 19 – 21 GHz but they do not explain anything and they do not show any in band result. Please note that this information is really important and should be added. Otherwise, the achievement should be removed from the paper.

6.       The authors claim that they optimize the antenna but the procedure is not discussed. In addition, the starting point in any optimization process is required.

7.       The three antenna optics compared in Table 2 and described in the paragraph under Table 1 are not fully described and they should be. However, the main drawback is that the comparison is not fair since the geometry of the two parabolic reflectors are different and the planar reflectarray optics is not equivalent. As a result, the comparison could be not valid. It is very well known that the gain obtained with a reflectarray and a parabolic reflector are almost the same except for the losses if they are really equivalent (illumination and aperture).

8.       In order to appreciate the performances of the antenna, a zoom in of Fig. 6 around the beam in both planes should be shown. In addition, a more detailed discussion of this figure should be included in the paper. In the case of Fig. 6(b) the authors do not point out if this curve corresponds to simulations or measurements. In my opinion, the same cases shown in figure 6(a) should be also included.

9.       A comparison of the curves in fig. 7 with results from simulations would be welcome for validation of the model used in the design.

Author Response

Pleae consider the point-by-point response provided in the attached pdf.

Author Response File: Author Response.pdf

Reviewer 2 Report

This work presented an interesting improvement in cylindrical parabolic reflector antenna. This work is sound and presented well. Following concerns:

- Final measured gain in Fig. 7 seems very interesting. Please add detailed description on the measurement setup, which standard gain antenna was used, which Anechoic environment was used. This is important to show sufficient information to ensure repeatability of the same gain values. 

- In addition to citing [12], please add description of the spillover efficiency. 

- Please re-phrase the sentence: "With respect to different patch antennas, is preferable...
". Can not understand. 

- Please re-format the references. Preferable using Journal short forms like IEEE Trans. Antennas Propag.

Author Response

Pleae consider the point-by-point response provided in the attached pdf.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have adequately addressed the comments of the reviewers. I do not have further concerns on the work.