Additive Manufacturing of a Passive Beam-Steering Antenna System Using a 3D-Printed Hemispherical Lens at 10 GHz

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

A mechanically beam-steerable antenna system consisting of a rectangular microstrip patch antenna integrated with a 3D printed hemispherical dielectric lens fabricated via stereolithography (SLA), and a 3D printed rotatable support structure fabricated using fused deposition modeling (FDM) is proposed in this paper. The following items needs to be addressed for clarity and completeness of the paper.

 

1. Complex permittivity information or data sheet of the resin material used for the measurement of the photopolymer samples using Anycubic Photon Mono X 6K SLA printer needs to be provided for comparison. In addition, some photographs of the measurement setup for the permittivity and loss tangent of the photopolymer samples at 10 GHz using Keysight 85072A split-cylinder resonator should be included.
2. In lines 212 to 216 on page 6, it says that “The gap was optimized using full-wave parametric simulations in CST Studio Suite to strike a balance between forward radiation enhancement and input impedance matching. The electric field distributions confirmed that, g = 9 mm produces constructive wave superposition and minimal backscattering.” Pls. add some simulated comparison results for different g values.
3. Complex permittivity information of the ABS support structures fabricated using the FDM 3D printer used for the simulation needs to be provided.
4. Gain enhancement of the antenna integrated with the 3D-printed hemispherical lens is just 3.26 dB. How gain can be further improved to 6 dB or 10 dB?
5. In Figure 13, sidelobe level in the radiation pattern increases from -17 dB to – 8 dB when the rotation angle increases from 0 degree to 40 degrees. How this can be improved?
6. In Table 3, more recent papers for the beam-steering antenna systems should be added for comparison. In addition, volume comparison with other beam-steering antenna systems should also be included.
7. The design method and concept of the 3D-printed hemispherical lens and mechanical beam steering systems are well-known in the literature. What would be the novelty of the paper?

Author Response

Please see the point-by-point response in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper proposes an beam steering antenna system using mechanical parts. Although is is well organized, there are some severe issues:

1. Why to use a mechanical steering system? Of course, it is an option, but an electrical steering, such as phased arrays or dynamic metasurfaces, provides ultra-fast beam manipulation which is not feasible with mechanical.
2. What does it mean "scalability for low cost applications" in Table 3? Why [36] and [37] has low and [31], [32] and [35] medium scalability? How is this confirmed?
3. The 3D printing technique is used for the fabrication of the lens layer by layer. Is this true? If yes, then there is a possibility for the final material to be anisotropic. Is this considered? The mentioned homogeneity does not impose isotropy.
4. Sentence 203 refers to Fig. 3b, but it mentions 2D radiation patterns. However, the gain is sketched in this figure. Please explain.
5. Why this type of lens is selected? For example, a Luneburg lens could have been used. It is tougher to fabricate since it requires a material gradient, which has been accomplished with 3D printing, but its operation is considered superior in terms of gain enhancement.
6. The results in Fig. 8 (and as consequence in Fig. 13 and Table 2) are strange. The conventional antenna at 0 degrees has 6.7dBi and at 45 degrees approximately 3dBi (~3.5dBi). However, the gain difference with the lens is less than 1dBi. How is this possible?

Author Response

Please see the point-by-point response in the attached file.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

In this paper, Sangpet et. al. proposed a mechanically beam-steered antenna system for 10 GHz applications, enabled by multi-material 3D-printing technology. The proposed design eliminates the need for complex electronic circuitry by integrating a mechanically rotatable, 3D-printed hemispherical lens with a conventional rectangular patch antenna. The system comprises three main components: a 10-GHz patch antenna, a precision-fabricated hemispherical dielectric lens produced via stereolithography (SLA), and a structurally robust rotation assembly fabricated using fused deposition modeling (FDM). The mechanical rotation of the lens enables discrete beam-steering from −45° to +45° in 5° steps. Experimental results demonstrate a gain improvement from 6.21 dBi (standalone patch) to 10.47 dBi with the integrated lens, with minimal degradation across steering angles (down to 9.59 dBi). Simulations and measurements show strong agreement, with the complete system achieving 94% accuracy in beam direction. This work confirms the feasibility of integrating additive manufacturing with passive beam-steering structures to deliver a low-cost, scalable, and high-performance alternative to electronically scanned arrays. Moreover, the design is readily adaptable for motorized actuation and closed-loop control via embedded systems, enabling future development of real-time, programmable beam-steering platforms. Here below are some minor comments:

(1) How about the distance between the patch antenna and the dielectric lens? I mean if the lens is in the near field region of the antenna, then it might affect the radiation of the patch, especially for the oblique incidence scenario.  

(2) It would be better for the authors to illustrate the 3d printing details, since not all the authors are familiar with this techniques.

(3) Some recent works might be helpful for the antenna design, for example (a) Nature Communications, 16, 5953, (2025), and (b)  Advanced Science. 2001437, 2020.

(4) Minor edits: The axis title is wrong for Fig. 8. The x axis should be theta?

Author Response

Please see the point-by-point response in the attached file.

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The topic of this manuscript entitled: "Additive Manufacturing of a Passive Beam-Steering Antenna System Using a 3D-Printed Hemispherical Lens at 10 GHz" falls within the profile and scope of the Electronics.

Recommendation – Consider after minor changes

In the work mechanically beam-steered antenna system for 10 GHz has been proposed. Proposed system is composed of patch antenna, hemispherical lens antenna and rotating system.

Comments:

- Authors should argue why the frequency of 10 GHz was chosen for investigation. In what communication system the proposed antenna can be applied. Such information is important to verify the utility of the antenna.

- Argumentation that the system with rotating lens is better solution than rotating of the entire antenna is not convincing. The construction of the system with the rotating lens is mechanically more complex and radiation patterns of the antenna system are different in the function of the rotating angle (Fig.8). In addition, the antenna gain is smaller comparing to other antennas or antenna arrays.

- In Fig.8 instead of “Frequency (GHz)” should be “Rotating angle”.

Author Response

Please see the point-by-point response in the attached file.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The revised paper has been improved considerably by reflecting the reviewer’s comments, but the following issues still need to be clarified for completeness of the paper before publication.

 

1. The electric field distributions for three representative values (g = 7 mm, g = 9 mm, and g = 11 mm) are presented to show the optimization of the air gap in the revised manuscript. It would be better if the variations in the input reflection coefficient and gain characteristics are provided for comparison.
2. For gain enhancement, the simple method might be increasing the radius of the lens. Some simulation results for the varying the radius of the lens need to be added.

Author Response

The authors thank the reviewer for the valuable comments that helped improve the quality of the manuscript. We have revised the manuscript accordingly, and the detailed point-by-point responses are provided in the attached file.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The authors did a good job in the revised manuscript. There is a couple of additional comments that will help with the clarification of significant concepts:

1. Considering the isotropy of the material, it is expected to measure the permittivity for different material orientation. This will highlight that "the dielectric properties are close to isotropy".
2. An electric field distribution figure (such as in Figure 5) must be included for different rotation angles of the  hemispherical lens. This will highlight that the "the main lobe follows the rotation of the lens".

Author Response

The authors thank the reviewer for the valuable comments that helped improve the quality of the manuscript. We have revised the manuscript accordingly, and the detailed point-by-point responses are provided in the attached file.

Author Response File: Author Response.pdf

Round 3

Reviewer 1 Report

Comments and Suggestions for Authors

Accept.