Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper extensively investigates the thinned and sparse beamforming for semicircular-FDAs in transmit-receive domain. Three types of non-linearly increased frequency offsets are investigated to alleviates the range-angle-coupled characteristic of FDA beampattern together with the non-uniformly spaced array configuration. The work can provide effective suggestions for relevant researchers. Besides, the manuscript is well organized. Several comments are provided in the following:

1. Why was the semicircular geometry selected amongst the many other canonical planar array geometries?

2. It may be better to add the analysis of convergence property for the proposed approach in Section 4.

3. The specific constraints on the mainbeam width in range and angle dimensions during the optimization should be provided in Section 4.

4. In equations (19) and (20), parameters Ri and qj are undefined. Please provide its definition.

5. In Figure 13 (a) and Figure 15 (a), why does the sparse FDA have asymmetric sidelobe and how does it differ from the other two approaches?

6. There are several grammatical errors in the manuscript. The author should check the manuscript for approval and fix such errors. In addition, authors should improve the writing of papers to enhance their readability.

Comments on the Quality of English Language

 Minor editing of English language required.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper investigates transmit-receive thinned and sparse synthesis for semicircular-FDA. The number of antenna elements can be reduced by half by using this approach, while maintaining good spatial focusing performance. Even through the mainlobe width is slightly widened after optimization, the proposed method has its advantage because it is more cost-effective. The following provides some concerns:

1. Why semicircular other than circular, or cylindrical array configuration is chosen for your research?

2. How are Eqs. (2)-(4) obtained, and where is the reference?

3. There are other potential applications of FDA, such as high-resolution and wide-swath SAR imaging, you can list more extensive.

 

Comments on the Quality of English Language

Overall, the manuscript is written in clear and understandable English. However, some details can be further improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Authors report on the simulated results for the controlled beamforming FDA.

This paper is well written and well organised. And the work is quite interesting. The reviewer has the following comments.

- You need to check the your FDA beampatterns in time-domain because FDA antennas should be investigated thoroughly as a frequency shift progresses. And you need to investigate full-wave analysis in spectral and time-domain for your array scheme considering beampattern performance due to mutual couplings between radiating elements.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf