Design of Hybrid Fractal Integrated Half Mode SIW Band Pass Filter with CSRR and Minkowski Defected Ground Structure for Sub-6 GHz 5G Applications
, Mostafa Elkhouly 1, Renato Zea Vintimilla 1, Arnab Chakraborty 2 and Shweta Srivastava 2
Round 1
Reviewer 1 Report
In this paper, a HMSIW bandpass filter with hybrid fractal on upper plane and a CSRR along with a DGS etched on bottom plane is proposed. The publication of the manuscript in micromachines can be considered providing the following comments and questions are addressed:
1. Please check the format of the references and Table 1.
2. Please explain the advantages of the proposed hybrid fractal compared with the Minnowski curve and Koch curve.
3. Too many grooves are etched to increase the loss, from figure 9 and figure 12, the DGS design is too complicated and the boost in performance is small if any. Please explain.
4. The bandwidth is a bit wide, please add the comparative data of the bandwidth and out-of-band suppression with other papers in the final table.
Author Response
REVIEWER # 1
- Please check the format of the references and Table 1.
RESPONSE: Thanks for pointing it. I have checked and corrected format of references and Table1.
- Please explain the advantages of the proposed hybrid fractal compared with the Minkowski curve and Koch curve.
RESPONSE: Minkowski fractal geometry provides the wide operational bandwidth due to its multiple resonance property [1]. Also, Minkowski fractal has merits of providing better return loss [2]. On the other hand, Koch fractal has been selected as it is used as space filling structure that encompasses much more electrical length inside a fixed physical space resulting in compact size [2-3]. The hybrid shape of the Minkowski - Koch fractal curve is generated using the Iterative Function System (IFS). Minkowski and Koch curve geometries are merged to scale down the filter size and enhancing the return loss and bandwidth. Hence, the hybrid geometry brings out the best of both the parent geometries.
[1] Tripathi, Shrivishal; Mohan, Akhilesh; Yadav, Sandeep, “Ultra-wideband antenna using Minkowski-like fractal geometry”, Microwave and Optical Technology Letters, 56 (10), 2273–2279, 2014
[2] Narinder Sharma, Sumeet Singh Bhatia, “Comparative analysis of hybrid fractal antennas: A Review”, International Journal of RF and Microwave Computer-Aided Engineering, Vol. 31, Issue 9, 2021 e22762.
[3] Muchhal N. and Srivastava S., “Design of miniaturized high selectivity folded substrate integrated waveguide band pass filter with Koch fractal”, Electromagnetics, vol. 39, issue 8, pp. 571-581, 2019.
This has been given on page 2 of revised manuscript and highlighted by yellow colour.
- Too many grooves are etched to increase the loss, from figure 9 and figure 12, the DGS design is too complicated and the boost in performance is small if any. Please explain.
RESPONSE: Yes, it is correct that etching many grooves increase the insertion loss which is 0.62 dB in Fig. 9 and it slightly rises to 0.85 dB in Fig. 12. But adding a DGS has improved the overall performance of the proposed band pass filter as:
- There is great improvement in filter selectivity or roll off rate (ROR). As can be seen from Fig. 9, without using DGS the roll off rate is low (~25 dB/GHz) but after introducing DGS, there is lot of improvement in ROR (~70 dB/GHz). Also the stop band response of filter has improved after introducing DGS.
- After introducing DGS, there is enhancement in the bandwidth. It increased from 1.05 GHz to 1.52 GHz after intruding the fractal DGS in ground plane.
Please note this information has been provided in manuscript.
Q4. The bandwidth is a bit wide; please add the comparative data of the bandwidth and out-of-band suppression with other papers in the final table.
RESPONSE: The Table has been revised as per suggestion & it has been given on page no 9.
|
Refer ence |
fo (GHz) |
RL/IL* |
Technique Used |
Avg. Roll off rate# (dB/GHz) |
3-dB FBW (%) |
Out of band rejection (> -20 dB) |
mm x mm (λ0 × λ0) |
|
[9] |
5.3 |
20/1.8 |
FSIW Technique |
46 |
6.2 |
0.68 fo |
29.6 ×7.6 (0.62 λ0×0.26 λ0) |
|
[10] |
3.7 |
18/1.1 |
Slot and cross coupling technique |
57.5 |
14.2 |
N.A. |
120 x 30 (1.47λ0 x 0.37 λ0) |
|
[11] |
6.11 |
19/1.2 |
CSRR |
52.5 |
8.9 |
3.28 fo |
25 X 9.5=237.5 (0.52λ0 x 0.19 λ0) |
|
[12] |
4.67 |
15/1 |
Multimode HMSIW |
64.5 |
69.3 |
0.65 fo |
43.5 x 29.5 (0.69λ0 x 0.46 λ0)
|
|
Proposed |
5.2 |
14.5/1.1 |
HMSIW with DGS and CSRR |
72 |
26.3 |
4.1 fo |
27.8 x 7.25 (0.55λ0 x 0.21 λ0)
|
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper uses the CSRR to reduce the size of the SIW transmission line filter and the fractal DGS together with the CSRR implant a few transmission zeros for stopband performance enhancement. The abovementioned structures have been thoroughly investigated by many other researchers, and the authors put them all together in designing the filter. This paper has achieved the merit of smaller circuit size and better upper stopband performance but I think the novelty of this paper is fair and the technological innovation is also fair.
A comprehensive explanation of the fractal structure on the SIW’s top wall should be addressed since its role in this circuit design is unclear. And the reason for the bandwidth increasing is also needed to be elucidated in detail.
Author Response
REVEWER # 2
Q1. A comprehensive explanation of the fractal structure on the SIW’s top wall should be addressed since its role in this circuit design is unclear.
RESPONSE: Minkowski fractal geometry provides the wide operational bandwidth due to its multiple resonance property [1]. Also, Minkowski fractal has merit of providing better return loss [2]. On other hand, Koch fractal has been selected as it is used as space filling structure that encompasses much more electrical length inside a fixed physical space resulting in compact size [2-3]. The hybrid shape of the Minkowski - Koch fractal curve is generated using the Iterative Function System (IFS). Minkowski and Koch curve geometries are merged to scale down the filter size enhancing the return loss and bandwidth. Hence, the hybrid geometry brings out the best of both the parent geometries. Final hybrid fractal structure is achieved by iterating the miniaturized generator structure seven times according to the fractal theory and the total length l of the curve is given by [4]:
l = L(N/r)n (1)
where, L is the length of the initiator, n is the number of iterations, and N/r is the factor by which the initial length is increased at the first iteration.
[1] Tripathi, Shrivishal; Mohan, Akhilesh; Yadav, Sandeep, “Ultra-wideband antenna using Minkowski-like fractal geometry”, Microwave and Optical Technology Letters, 56 (10), 2273–2279, 2014
[2] Narinder Sharma, Sumeet Singh Bhatia, “Comparative analysis of hybrid fractal antennas: A Review”, International Journal of RF and Microwave Computer-Aided Engineering, Vol. 31, Issue 9, 2021 e22762.
[3] Muchhal N. and Srivastava S., “Design of miniaturized high selectivity folded substrate integrated waveguide band pass filter with Koch fractal”, Electromagnetics, vol. 39, issue 8, pp. 571-581, 2019.
[4] Lokenath Debnath, “A brief historical introduction to fractals and fractal geometry”, International Journal of Mathematical Education in Science and Technology (Taylor & Francis), 37:1, 29-50, 2006
This has been given on page 2 and 3 of revised manuscript and highlighted by yellow and green color.
Q2. And the reason for the bandwidth increasing is also needed to be elucidated in detail.
RESPONSE: The simulation result shows that the proposed filter has an increased bandwidth of 1.52 GHz due to addition of DGS. This increase of bandwidth can be explained by the fact that the ground plane’s defect augments the fringing field causing parasitic capacitance. This improved bandwidth is due to the higher coupling between the top and the ground plane, which results in improved bandwidth.
This has been given on page 8 of manuscript and highlighted by green color.
Author Response File: Author Response.pdf
