Design of a High-Gain X-Band Electromagnetic Band Gap Microstrip Patch Antenna for CubeSat Applications
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors proposed a microstrip patch antenna with EBG structure to enhance the gain at X-band. Some questions are shown as follows.
- Why the Case h has the best performance?
- The mechanism part of the antenna is too short to well understand.
- What is the function of the EBG in this design. Please give the physical reason.
- Fig. 12 should indicate which case.
- Why the gain is much lower than the antenna in Ref. [5]?
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for Authorselectronics-3642174; review report; 1st
Authors presented a design of a microstrip patch antenna operating at 8.483 GHz for CubeSat applications. They employed a probe-fed rectangular patch. Circular polarization is obtained by forming, on the patch, two rectangular slots of different sizes. To increase antenna gain, a rectangular EBG fence is placed around the patch. The manuscript is well-structured and well-written.
My comments are as follows.
- A question on author's interpretation of the operating principles of the EBG fence.
In Lines 138-144, authors wrote "The enhancement of antenna gain and radiation efficiency due to surface wave suppression can be explained for these two cases as follows: For the single element MPA, the surface waves travel along the substrate and radiate from the edges of the antenna, contributing to the unwanted edge radiation that degrades the antenna efficiency. By filling up the non-metal space from the center radiator to the edges of the MPA by EBG elements, stopband ‘rings’ is created and prevents the surface wave from going beyond the patch area."
In Lines 148-150, authors wrote "When separating the antenna elements by mushroom-type EBGs, stopband ‘trenches’ are created and the mutual coupling caused by surface wave between them will be decreased. Therefore, the antenna gain and performance will be boosted in both cases."
Figure 6 shows a difference of about 3.5 dB in the gains of a patch without the EBG fence and the one with the EBG fence. Authors explain that the gain increase is due to surface wave suppression. I highly doubt this logic.
- Considering a rather large substrate thickness, the surface wave loss is too much. 3.5 dB corresponds to 45% of the power. If a surface wave loss is this large, then the gain of a single patch should not be as high as 8.27 dBi.
- The contribution of the surface wave loss can be checked by removing the dielectric around the single patch while retaining the ground plane. Without a dielectric, the surface wave is not easily excited at least at 8.483 GHz. This can be checked by simulation.
- By examining Figure 8b, it appears that the EBG fence acts like a set of parasitic patches resulting in an increased gain.
- If the purpose of the EBG fence is just to suppress the surface wave, then the distance between the patch and the fence should have little effect as far as they are apart at least by the patch size.
Please re-investigate the operating principles of the EBG fence and make corrections if applicable.
- Objection to the authors' view on the advantage of the proposed design.
In Lines 48-58, authors wrote "There are various reported works related to X-band MPA for CubeSat: Benedikt Byrne et al. [4] designed a compact, optimized circular polarization MPA array for payload Telemetry (TM), this antenna operates at 8.025-8.4 GHz with the measured gain of more than 10 dBi and the measured axial ratio (AR) of lower than 3 dB at 8.212 GHz. However, the design was quite complicated with feeding network and antenna elements on the feed layer, as well as a separate parasitic layer. A high gain CP planar antenna with superstrate integrated on top of the antenna radiator was introduced in [5], the gain is 17dBic; nevertheless, the feeding network is complicated with 4 different pins to provide differential signals for CP. Furthermore, the total height of this antenna exceeded the threshold specified in the CubeSat Design Specification (CDS) developed by California Polytechnic State University (Cal Poly) and Stanford University [6]."
The advantage of the proposed design:
- Single layer
- No feed network
The disadvantage of the proposed design:
- The substrate thickness 1.5 mm is too high for 8.483 GHz.
- Soldering in too many places (a total of 17).
One can do a quick literature survey and can find a simple design with a thinner single substrate with a simple feed network that offers a comparable bandwidth and gain. For example, one can apply the design by
- Torres-Garcia, et al., "Broad circular polarized field generation in single layer microstrip patch antennas", 2026 EuCAP; https://ieeexplore.ieee.org/document/7481915
for 8.483-GHz antenna. The above work proposes a single element, but it can be extended to an array configuration using a simple feed network on the same plane. The substrate thickness h = 1.5 mm at 2.4 GHz. At 8.483 GHz, it will be 0.42 mm.
- Please add some comments on limitations or disadvantages on the proposed design. Or rather future works on the improvement of the proposed design.
- Bandwidth requirement for the gain, reflection coefficient and axial ratio has not given. Please specify.
- Table 2:
'Measured 3-dB ARBW 25 MHz'
Figures 9 and 19 tell a different story. Please check and make a correction if applicable.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe topic of this manuscript entitled: "Design of A High Gain X-band Electromagnetic Band Gap Microstrip Patch Antenna for CubeSat Applications" falls within the profile and scope of the Electronics.
Recommendation – Consider after minor changes
In the work the microstrip antenna for satellite communications has been proposed. The antenna has been preferred for CubeSat satellites and operates in X-band.
Comments:
- The designed antenna consists of central radiating patch surrounded by 16 metallic plates. These plates should improve the electric performance of the antenna. It was suggested that antenna performance improvement has been reached due to metamaterial property of the antenna structure. In fact, the metamaterial property of the structure was not demonstrated.
- In Fig 7. The antenna patterns should be normalized to maximal values for easier comparison. The values of the main lobe magnitudes were mentioned under drawings.
- The main lobe of antenna pattern is rather broad. This can be a large drawback in the satellite communications. The difference of 3.4 dB between original MPA and CP EBG antennas is not satisfying even for LEO.
- In Fig 10g and 10h the antenna geometries are similar so why in Fig 11 the gains differ for case g and h.
- The important antenna performance is the circular polarization. Such property should be demonstrated with measurement. The easiest way to determine the circular or elliptical polarization is to use two orthogonal linear antennas. In the work a pair of helical antennas were used to determine the antenna pattern using specialized software. Please discuss more widely this problem
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors have answer the questions. I have no more comments.
