Extreme Sparse-Array Synthesis via Iterative Convex Optimization and Simulated-Annealing Expanded Array

Round 1

Reviewer 1 Report

In my opinion, this article lacks originality. It seems as if it were written in the nineties. Currently, the interest in optimizing linear arrays is low. In some fields, it is not a technological challenge to manage the number of elements that make up a phased array (around 128 elements), and there are multiple solutions to this problem. For this reason, I believe that this type of article should provide a different perspective highlighting their contribution.

It is difficult to say which design methodology is better if it is not based on a statistical analysis of the results. In problems where there can be several solutions, an isolated result can be a consequence of chance and it does define the goodness of the design method. You have to do a statistical analysis of the results with different configurations (the number of active elements and size of the array). Current computing capabilities allow this study at relatively low cost (for narrowband, unidirectional, and linear arrays).

The analysis of the result (the opening) is very poor. No results are presented in direction (absolutely necessary); and the comparison with other matrix configurations is difficult to evaluate. The room for improvement does not seem to be very significant, or if it is, it has not been explained. In my experience, for convenience of electrical resources (circuit packaging), the layout of a 50 lambda array can be reduced to 64, 32, and 16 elements. Other numbers require a more complex circuit. In my opinion, for an aperture of 100 elements, reducing it to 43 is not being extreme.

The values of the apodization weights in the table should be normalized. It is rare for the beampattern to be symmetric when the apodization mask is not. I anticipate that directing the beam pattern will worsen this result. I may be wrong, but the author has not shown it.

The article must refer to the application. It is different if We are talking about systems that -operate in broadband or in close and if it is only unidirectional or pulse-echo. These considerations can affect the results. Also the author should consider that in the real world there are many inaccuracies when performing the apodization mask. If the solution is based on it, the robustness to these inaccuracies could be studied.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

COMMENTS:

 

The submitted manuscript presents a new technique for the design of sparse arrays. The proposed method is based on a combination of iterative convex optimization and simulated annealing algorithm. It is certainly of interest to most readers of Electronics. Some comments are listed below to improve the quality of the work.

 

1) Why does the title of Section 2 refer to “Materials”?

2) Please check the far-field condition presented in line 74. If needed, add a reference to support the information.

3) Why the modulus function is used in two conditions of the minimization problems in (4), (5), and (6) since the function B is always non-negative?

4) Is the condition |B(ml)<=1| in the minimization problems used to address the patterns with more than one main beam? It could be clarified in the text.

5) Please check references [9] and [10] in the references list.

6) Please check the number of array elements in line 172.

7) In the example shown in Section 3, the value adopted for the parameter epsilon should be mentioned since its important for the minimization problem (6).

8) The authors should show at least one more example to demonstrate the effectiveness of the proposed technique. If possible, illustrate a situation in which the main beam is not pointing at the broadside (as in the previous example).

9) Please check the information in parenthesis in lines 148 and 149.

10) The authors should mention the computation time to perform the design of the array in the example of Section 3.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

I appreciate the efforts of the authors to improve the exposition. I see the article much more interesting.