Development of Enabling Technologies for Ku-Band Airborne SATCOM Phased-Arrays

Round 1

Reviewer 1 Report

The authors should make a English proofreading of the manuscript.

As it is claimed in the paper that the main problem for this type of application is weight, size, and cost, a comparison should be made for these three variables in relation to other existing or foreseen possibilities of implementation.

Author Response

Dear Reviewer,

We want to thank for the pertinent suggestions and constructive criticisms.
All the minor changes requested have been implemented compatibly with the limited time available.
As suggested, we have elaborated the introduction to better compare the electronically solution wrt the others.
Since the scope of the article is to provide a state of the technologies and configuration for the fully phased array antennas able to guarantee the satellite pointing and performance for any aircraft route; the topic has been debated in general.

Thank you for your support and waiting for your feedback.
On behalf of all the authors,

Alfredo Catalani

Reviewer 2 Report

The manuscript presents interesting ideas and antenna technology development, which is of interest to the SatCOM antenna community. The work is technically thorough, and is presented in a succinct manner, easy to follow. I have some minor comments for the authors to improve the presentation of the work. Firstly, it will help to summarise the content of the article in the introduction section, stating clearly that the paper presents and overall antenna array implementation concept for Ku-Band airborne-satcom, and presents detailed design and test results for a proposed antenna element, integrated with the RF front-end. Secondly, pls provide the sizes of the antenna features in Fig. 6. It may help to include the sizes in both, millimeters as well as in relative wavelengths. Could the authors comment on the overall edge-to-edge size of the antenna element in Fig. 6 and 7. How does it compare in relative wavelengths? Would this size have any implications in terms of generating grating lobes, when assembled together in the array configuration? Could you pls comment if there is a methodology of suppressing such grating lobes, or if the grating lobes may be ignored in this specific application? Inf Fig. 25, are the high sidelobes near 60 degrees grating lobes? If so, it could be useful if the authors include a simple calculation in the manuscript on how these lobes are stemming due to the physical size of the single element, and how much spacing between the elements is there, causing these grating lobes.

On a minor note, consider revising the paragraphs presentation as some sentences appear to be abruptly starting out, instead of continuing in the previous paragraph. This is a case at a number of places within the manuscript. For example, Section I, paragraph 2 "Moving from expiremental..." should be combined with "To be commercially..." in the same paragraph, rather than individual paragraphs. This would improve readability and presentation. 

In table I, pls correct the hyphen sign to replace it with divide sign in Frequency Bands values.

Author Response

Dear Reviewer,

We want to thank for the pertinent suggestions and constructive criticisms.
All the minor changes requested have been implemented compatibly with the limited time available.
As suggested, we have elaborated the introduction to better compare the electronically solution wrt the others.
We added more information on the antenna geometrical characteristics, also for the radiating element, and the justification on the grating lobes have been included. As you correctly noted, in Fig. 25 it is visible the grating lobe due to the 22 mm inter-spacing of the 5 element linear array; but it is to remark that it happens only or the breadboard; while for the complete configuration the grating will be spread.

Thank you for your support and waiting for your feedback.
On behalf of all the authors,

Alfredo Catalani

Reviewer 3 Report

This paper discusses the development of an electronic transmit-receive phased-array antenna in Ku-band for aircraft communications via satellite. This reviewer suggests to address the following concerns before the possible publication:

1. I would suggest to provide a clear comparison of your development with the currently available developments. Clearly state how this development is different from what's available in the literature. Also, it would be good if you summarise the main contributions of this work.  
2. Literature review is missing. 
3. Legends in some of the figures are missing.  

Author Response

Dear Reviewer,

We want to thank for the pertinent suggestions and constructive criticisms.
All the minor changes requested have been implemented compatibly with the limited time available.
As suggested, we have elaborated better the introduction and we added the missing legends for several figures.

Thank you for your support and waiting for your feedback.
On behalf of all the authors,

Alfredo Catalani