Dual-Band Antenna on 3D-Printed Substrate for 2.4/5.8 GHz ISM-Band Applications
Round 1
Reviewer 1 Report
1. It is not clear what the research question is?
2. What is the main motivation for using 3D printing in this design? What problem does 3D printing technology solve by simply changing the substrate?
3. The motivation for using the SRR is not clear at all. Matching issues are solved by choosing the optimal excitation parameters. Correction of the shape of the radiation pattern is also a big issue.
4. Fig. 3 colors are the same for the curves, it is not possible to understand.
5. Evaluation of radiation efficiency using EM simulation does not make sense. When you make a design out of foil by hand-cutting slits and gluing onto a printed substrate, this should be done in experimental studies.
6. In the Cost/Complexity table, the design looks the most complex in terms of the number of manual operations.
Author Response
- It is not clear what the research question is?
- Contributing to the field of antenna design by designing a dual-band antenna using 3D printing technology, taking advantage of its many benefits, with maximized performance, low-cost and easy integration into telecommunication devices and systems. By receiving and transmitting data in two operating bands (2.4 GHz & 5.8 GHz), the goal is to solve interference problems and offer higher transmission rates and bandwidth.
- What is the main motivation for using 3D printing in this design? What problem does 3D printing technology solve by simply changing the substrate?
- The main motivation for using 3D printing technology in this design is that it offers the ability to be manufactured in a fast, easy, eco-friendly, and inexpensive way, while not hindering creativity.
In the proposed design, 3 3D-printed planar substrates are defined, with heights of 1mm and 2 mm. These values are not available for commercial substrates. Therefore, 3D printing makes it possible to obtain custom-sized substrates with good electrical performance, reducing the environmental impact.
- The motivation for using the SRR is not clear at all. Matching issues are solved by choosing the optimal excitation parameters. Correction of the shape of the radiation pattern is also a big issue.
- The split ring resonator (SRR) placed on top is used to change the radiation pattern shape at 5.8 GHz. The SRR acts like a director, modifying the electric field distribution radiated by the rectangular slot antenna. With the objective of giving you a graphical explanation, an extra simulation has been performed. A rectangular layer that occupies the cross-section of the structure and beyond is drawn in the YZ plane, then, the electromagnetic fields are plotted on this layer.
Figures 1 and 2 depict the electric and magnetic fields plotted in the cross-section of the simulated structures. Figure 1 contains the rectangular slots and the reflector plane, whereas Figure 2 is the final proposed antenna geometry. It is easy to observe the changes in the field distribution comparing figures 1 and 2.
The SRR is not used to attain matching at the input port; this element, however, also improves the reflection coefficient.
On the other hand, the excitation parameters have been carefully chosen, notwithstanding, there are some limitations for the manufacturing process used for this device, as some steps are handmade, for example the feed line, therefore the dimensions of the feedline can vary a little even if its geometry has been carefully designed.
The extra split rings (3-SRs & CSRR) are used to enhance the return loss of the antenna in the second band of operation without significantly affecting other parameters. These extra split rings make the metallic layers behave as defected ground structures (DGS). DGS is a widely known and used technique to enhance antenna performance.
Figure 1 Electromagnetic fields in magnitude plotted on the cross-sectional view at 5.8 GHz without SRR.
Figure 2 Electromagnetic fields in magnitude plotted on the cross-sectional view at 5.8 GHz with SRR.
We have added these two figures to the manuscript in Section 2.2, and also included a brief explanation to clarify this issue.
- 3 colors are the same for the curves, it is not possible to understand.
- We apologize for this inconvenience, an error occurred when the figure was generated. We have added a modified version of this image using a different color scheme as well as dashed lines.
- Evaluation of radiation efficiency using EM simulation does not make sense. When you make a design out of foil by hand-cutting slits and gluing onto a printed substrate, this should be done in experimental studies.
- Thank you for your noteworthy observation, we are completely conscious that the radiation efficiency values will be different from simulated ones. We have eliminated the simulated radiation efficiency of the abstract. In the results and conclusion sections we point out that the mentioned values are obtained from simulations to avoid confusion.
The measurement of radiation efficiency is not possible due to instrumentation issues, but we believe that the simulated results predict the real performance of the proposed design since the measured parameters show a good correlation with the simulated ones.
- In the Cost/Complexity table, the design looks the most complex in terms of the number of manual operations.
- The complexity in this table is related to the design and manufacturing. We consider that the proposed design is simple to fabricate since the substrate and the metal parts can be made in less than 5 hours and do not require many tools and materials. The manufacturing process can be improved using a 3D-printer with more capabilities, for example, a printer capable of printing metal parts, thus the manual operations can be totally eliminated. However, considering your comment, the table has been modified, the word “Low” was replaced by “Moderate”.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work proposed a dual-band antenna based on 3D-printed substrate. SRR, CSRR and SR are used to improve the radiation pattern and the input reflection coefficient, respectively. The novelty is limited, and I have some comments:
1） Can you explain why the size is large, especially the height, but the bandwidth is limited.
2） The manuscript focus on the parameter study, but lack of theoretical analysis.
3） Fig.3 is not clear, both with/without RP using the same type of the curve.
4） How about the measured results of the radiation pattern.
Minor editing of English language required
Author Response
This work proposed a dual-band antenna based on 3D-printed substrate. SRR, CSRR and SR are used to improve the radiation pattern and the input reflection coefficient, respectively. The novelty is limited, and I have some comments:
- Can you explain why the size is large, especially the height, but the bandwidth is limited.
- To provide a clear explanation, the following aspects should be taken into consideration:
- Antenna bandwidth in general depends on antenna geometry, materials, input impedance, efficiency, and polarization, not only on the height.
- The size of this design in terms of wavelength at 2.4 GHz is .
- The “impedance bandwidths” of the proposed work are close to 5% and 3%, respectively, in the two operation bands, considering the magnitude of the input reflection coefficient ().
We considered that the antenna is of medium size considering the wavelength at the lower operation frequency, which will be the largest, and the impedance bandwidth is narrow due to the overall geometry, narrow rectangular slots, feed line dimensions, proximity feeding, and substrate thickness.
- The manuscript focus on the parameter study, but lack of theoretical analysis.
- Thank you for your keen observation. A theoretical analysis can be performed from different points of view; for example, based on the geometry, material characteristics, mechanism of operation, radiation characteristics, or purely as mathematic modeling. Furthermore, it is clear that the main objective of a theoretical analysis is the understanding of how the antenna works.
The submitted paper contains the parametric study and the operation mechanism of the proposed antenna based on geometry. To answer the reviewer’s question, we herein address the issue in order to clarify the operation mechanism of the proposed antenna and establish a relation between geometry and operation mechanism.
Through the geometry-based analysis we have determined that the resonant length is influenced by the different elements that comprise the proposed geometry in different ways, giving as a result a total resonant length for each of the rectangular slots close to 0.4 at the frequency of operation.
The following equations are proposed in order to establish the relationship between the elements of the proposed geometry (considering the final dimensions) and the resonance length of the principal sources of radiation (the rectangular slots).
Where is the wavelength at the operation frequency, is the microstrip feed line termination, reflector plane effect, is the influence of the neighboring rectangular slot, is the SRR effect.
Some elements, such as the CSRR, and the 3-SRs on the reflector plane, do not have an important impact in the resonant length but have an appreciable one on the return loss. Additionally, the reflector plane does not have a considerable impact on because it is relatively far away from it.
The next figures show the electric field in the cross-section, the principal source of radiation can be observed, and the resonant length is indicated in the two operation bands.
Figure 3 Electric field in the cross-section in the two operation bands.
Finally, considering your important suggestion, and in order to delve deeper into the operation mechanism, we have added the two equations described above and a brief explanation in the manuscript.
- 3 is not clear, both with/without RP using the same type of the curve.
- We have changed the figure using different line styles.
- How about the measured results of the radiation pattern.
- We apologize for not presenting the measured radiation pattern; we have some issues with the antenna holder and rotation instrument; therefore, we cannot trustworthily measure the antenna for a full azimuthal cycle (360°).
Author Response File: Author Response.pdf
Reviewer 3 Report
The introduction is short but very clear and concise.
Fig. 2 a)
A parameter whose influence is not visible is either not within the scope of its influence on the S11 coefficient (parameter LF) or has no influence on that coefficient and therefore should not be analyzed. That picture (a)) should be: With RP and Without RP!
Fig.3.
The red and black lines are not clear in Figure 3.
Fi.5.
The excessive number of lines in Figure 5 obscures the basic intention of showing the influence of the H4 dimension!
Conclusion is correct!
Author Response
The introduction is short but very clear and concise.
- 2 a)A parameter whose influence is not visible is either not within the scope of its influence on the S11 coefficient (parameter LF) or has no influence on that coefficient and therefore should not be analyzed. That picture (a)) should be: With RP and Without RP!
- The figure has been modified considering you worthy comment.
- 3. The red and black lines are not clear in Figure 3.
- We have updated the figure, changing the color and style of the lines.
- 5. The excessive number of lines in Figure 5 obscures the basic intention of showing the influence of the H4 dimension!
- Taking your observation into account, we have decided to eliminate some lines in order to clarify the figure, highlighting the influence H4 has on the design.
- Conclusion is correct!
- Thanks! the word “simulated” was added to refer to radiation efficiency.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Most of the comments have been taken into account in the revised version of the paper. I believe that the paper can be recommended for publication.
Reviewer 2 Report
The authors have answered all my comments, and I think it can be acceptable right now.
No comments.
