Applicability of the Meniscus-Removal Method for Q-Band Liquid Characterization in Semi-Open Waveguide Cellâ€
Round 1
Reviewer 1 Report
The paper describes a dielectric characterization technique of liquids in partially filled waveguide. The main novelty of the method is the correction of the meniscus effect produced by the liquid surface when poured in the measurement fixture. The method seems to be viable and is clearly explained. However, it is missing an uncertainty analysis, together with the limitations of the method respect to the sample dimensions, frequency and permittivity values that ensure accuracy in the results.
- Line 24. Please clarify what do you mean by “multistate” measurements.
- Lines 25-30. I recommend to add a Figure explaining what the meniscus is and the different measurement configurations employed to de-embed it.
- Please provide an error analysis of the method, limitations respect to measurable dielectric properties of the sample and assumptions that must be fulfilled in the measurement setup to ensure the accuracy of the method.
Author Response
Dear Reviewer, we would like to thank you for your detailed review, which has helped us to improve the paper.
All the changes in the revised paper compared to the previous version are marked in blue in the Supplementary File.
Point 1: Line 24. Please clarify what do you mean by "multistate" measurements.
Response 1: We have added the explanation: "multistate measurements (of different volumes)."
Point 2: Lines 25-30. I recommend to add a Figure explaining what the meniscus is and the different measurement configurations employed to de-embed it.
Response 2: We have added the references to Figure 1, which shows the meniscus and the measurement configurations.
Point 3: Please provide an error analysis of the method.
Response 3: Thank you for that suggestion. Uncertainty analysis is a vast topic we plan to address in the future and is out of the scope of this particular paper. We have added that information at the end of the conclusions.
By the way, it is not the uncertainty analysis, however, you can check our paper "Errors in Broadband Permittivity Determination Due to Liquid Surface Distortions in Semi-Open Test Cell," where we analyze the systematic error introduced by the meniscus.
Point 4: Please provide limitations respect to measurable dielectric properties of the sample.
Response 4: We have added information about the limitations of the measured sample with the method concerning the sample dimensions and permittivity values in the conclusions. The frequency of operation is the whole bandwidth of the waveguide.
Point 5: Please provide assumptions that must be fulfilled in the measurement setup to ensure the accuracy of the method.
Response 5: We have added the assumptions and practical hints for measurements to achieve the best possible accuracy in the Section "Experimental results."
Thank you again for your review and the comments that have helped us to improve the paper.
Reviewer 2 Report
This manuscript describes a method for removing the effect of a liquid meniscus on dielectric measurements with a waveguide cell. It is an extension of the authors' previous work on a coaxial configuration, and it contributes to improvement of this type of measurements. I have just a few comments, which do not amount to major criticism.
line 67: It should say that eq.8 applies to a plane boundary.
lines 80-82: This sentence would be easier to understand if "Tsk" were omitted.
line preceding eq.22: What is the reason for using the median instead of the mean?
lines 194-195: Would measurements of more cases, providing different values of delta l, allow averaging to reduce the ripples in figs. 5 and 6? Also, could delta l be determined from the difference in liquid volume between cases? It might be worthwhile to consider these possibilities in the discussion section, in the context of future work.
Author Response
Dear Reviewer, we would like to thank you for your detailed review, which has helped us to improve the paper.
All the changes in the revised paper compared to the previous version are marked in blue in the Supplementary File.
Point 1: line 67: It should say that eq.8 applies to a plane boundary.
Response 1: We have added that information, thank you.
Point 2: lines 80-82: This sentence would be easier to understand if "Tsk" were omitted.
Response 2: Right, we have deleted "Tsk."
Point 3: line preceding eq.22: What is the reason for using the median instead of the mean?
Response 3: We have added an explanation that the median "is more robust to high errors and excesses than the mean value." The median value was the much better option for measurements at lower frequencies (0.1 – 18 GHz) for which the method was originally established.
Point 4: lines 194-195: Would measurements of more cases, providing different values of delta l, allow averaging to reduce the ripples in figs. 5 and 6?
Response 4: We have added the information about the reason for the ripples in the section "Experimental results" - the residual VNA calibration errors. These errors have a systematic character, and averaging does not eliminate them.
Point 5: lines 194-195: Could delta l be determined from the difference in liquid volume between cases? It might be worthwhile to consider these possibilities in the discussion section, in the context of future work.
Response 5: Thank you for that suggestion. We have added that perspective to the conclusions.
Thank you again for your review and the comments that have helped us to improve the paper.
Round 2
Reviewer 1 Report
The authors have properly addressed the suggested points.
