Fast Frequency Sweep Technique Based on Segmentation for the Acceleration of the Electromagnetic Analysis of Microwave Devices
Round 1
Reviewer 1 Report
This work presents a fast analysis method for microwave structures. The reviewer has the following comments.
1) Please be specific how the S parameters of each block is calculated, i.e., by a custom full-wave analysis code, or a commercial software? It would be instructive to have a discussion on whether the performance (in terms of accuracy and speed improvement) would be different when different solvers (e.g., FEM, FDTD, etc)
2) It would be great if the authors can provide a guideline on to divide the structures into smaller pieces. What is the trade-off between the granularity of the division and the performance (accuracy and speed)
3) It would seem to the reviewer that only simple inline structures can be analyzed using this method. Please comment on the applicability of the method to more complex structures such as cross-coupled filters and/or folded dual-mode filters.
Author Response
Dear reviewer,
Thank you very much for your comments.
In response to your first comment:
1) Please be specific how the S parameters of each block is calculated, i.e., by a custom full-wave analysis code, or a commercial software? It would be instructive to have a discussion on whether the performance (in terms of accuracy and speed improvement) would be different when different solvers (e.g., FEM, FDTD, etc)
The manuscript specifies for each one of the three examples how the scattering matrix of each building block has been computed. For the first example, the coupled cavities filter in rectangular, the manuscript explains:
In this case, these building blocks are either empty sections of rectangular waveguide (labeled as Line i in Fig. 2) or either H-plane inductive irises (labeled as Iris i in Fig. 2). The generalized scattering matrix (GSM) of the empty line sections can be compute analytically [23], and the GSM of the irises has to be obtained using a numerical method. In this case, the mode matching method described in [24] has been used, although any other method could also have been used, The fast frequency sweep procedure is not affected by the particular choice of analysis methods used for computing the scattering matrices of the building blocks, so its performance would be the same if other simulators were used for obtaining these matrices.
It can be noted that there is a reference to the fact that any other analysis method could have been used. The fast frequency sweep would work exactly the same, and in the revised version of the manuscript this has been properly discussed (see characters in bold).
In the second example, the coupled cavities filter in rectangular waveguide loaded with circular dielectric posts, the manuscript also explains how the scattering matrices of each building block are computed:
As in the previous filter, the GSM of the empty lines are obtained analytically [23], and the GSM of the irises are obtained with mode matching [24]. The GSM of the dielectric posts can be computed using, for example, the hybrid mode matching method of [25].
Finally, in the third example, the coupled cavities filter in substrate integrated waveguide, the manuscript explains:
In this case, the GSM of the building blocks has been obtained with the numerical method described in [1], which uses a hybrid method of moments and mode matching method
Second comment of the reviewer:
2) It would be great if the authors can provide a guideline on to divide the structures into smaller pieces. What is the trade-off between the granularity of the division and the performance (accuracy and speed)
The following text has been added to the new version of the manuscript, in the discussion, in order to attend this enriching comment of the reviewer:
It can be concluded that if the structure is divided into the smallest possible building blocks (such as empty lines, irises, dielectric posts, or metallic vias) the method is accurate and fast. The smaller the building blocks, the simpler the frequency response of each individual block, and the greater the final accuracy using this fast frequency method. At the same time, when the building blocks are very small, their scattering matrices can be reused for the same building block appearing in another part of the structure, and the total computation time is reduced
Third comment:
3) It would seem to the reviewer that only simple inline structures can be analyzed using this method. Please comment on the applicability of the method to more complex structures such as cross-coupled filters and/or folded dual-mode filters.
This interesting issue has been discussed in the new version of the manuscript, where the following text has been added:
p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 10.0px Helvetica; color: #ff0000} span.s1 {font: 5.0px Helvetica; color: #000000}
Although the fast frequency method has been applied here to inline structures, it could be also easily applied to more complex structures such as cross-coupled filters or folded dual-mode filters. The difference is that in those more complex structures some individual block should be a three or four ports device (such as a three port T-junction). But even a T-junction has a simple frequency response that can be easily approximated with splines with a small number of frequency points.
Reviewer 2 Report
The manuscript is interesting but very general and focused on devices for microwavecommunication, in particular the proposed method is applied to all metallic and dielectric loaded filters in rectangular waveguide, and SIW filter. In fact the analyzed building blocks are empty lines, irises and dielectric posts in rectangular waveguide, as well as metallized circular vias. In this form it be included in the special issue Substrate Integrated Waveguide (SIW) and its Applications. I suggest as major revision to strengthen the reference to SIW technology
Author Response
We thank the reviewer for his comments. We have indeed revised the manuscript and produced a new version. Since we are not sure that this paper is selected for inclusion in the special issue on Substrate Integrated Waveguides (SIW), we have not reduced the scope of the paper to SIW structures. As a matter of fact, we think that the proposed fast frequency sweep method is a general approach, and it is interesting for the reader to appreciate its potential use not only for SIW structures, but also for rectangular waveguides. Nevertheless, if required by the editorial board, we can reduce the parts dedicated to devices in rectangular waveguides, and focus on SIW structures.
Round 2
Reviewer 1 Report
I believe the authors have adequately addressed the reviewers' comments.
Reviewer 2 Report
The manuscript can be accepted in this form
