High-Speed Antenna Measurement System Using Multi-Probe Array Technique for 5G Applications

Round 1

Reviewer 1 Report

Overall the paper is well written and presents the information clearly. I would suggest that you include a reference to the test frequency on Figure 12 similar to you other figures.

Author Response

We appreciate valuable comment. Similar to other figures, it was changed by referring to the test frequency in Figure 12 and the figure file has been separately uploaded as well for your reference.

Author Response File: Author Response.pdf

Reviewer 2 Report

Please see the attached file.

Comments for author File: Comments.pdf

Author Response

1) Reviewer’s comment: There are too much contents about background in Abstract, which should be moved to Introduction.

Author’s response: We appreciate valuable comment. We have re-written Abstract as recommented by reviewer #2. The background of this article is described in Introduction.

“In this article, the high-speed antenna measurement system using multi-probe array technique for 5G application is suggested. The spherical near-field scan measurement system for millime-ter wave frequency band(3 GHz ~ 40 GHz) and the multi-probe array rotation method is adopted to improve the antenna measurement speed. The proposed measurement RF system consists of the 14 multi-probe array(28 channel with dual-polarization), switch matrix, downconverters, amplifiers/attenuators, digitizers and signal generators. The measurement speed performance can be improved significantly and the 3D beam pattern of the AUT can be achievable compared with the conventional planar near-field scan antenna measurement system. The designed system was verified through comparison with a verified far-field measurement system. In addition, an effective sampling technique, to increase the measurement efficiency, was also proposed and verified.”

 

2) Reviewer’s comment: It is suggested to use past tence to introduce the existing works.

Author’s response: We appreciate the reviewer’s comment. We have incorporated this suggestion in the revised manuscript

 

3) Reviewer’s comment: All of the references were published 3 years ago, which should be justified. It is suggested to introduce the following recent works in MIMO and beamforming fields [R1]-[R4] to highlight the state-of-the-art of this paper.

Author’s response: We appreciate the reviewer’s comment. We added the references of recent work in MIMO and beamforming fields [R2]-[R4] as proposed by reviewer 2.

 

4) Reviewer’s comment: The authors only introduced what they have done, while the  motivations and contributions are not well clarified, which should be further improved to emphasize the novelty of this paper.

Author’s response: We appreciate the reviewer’s comment. Previous antenna measurement system using multi-probe array is uses the vector network analyzer and switch matrix. Our proposed MPAR system consist of multiple antenna probes and a multi-channel digitizer. Therefore, it can simultaneously measure vertical/horizontal antenna characteristic results from all probes, which can dramatically reduce measurement time.

“The MPAR measurement system utilizes a multichannel digitizer to form 28 inde-pendent channels. By using two independent channels for each probe, the polarization (vertical/horizontal) can be measured simultaneously; thus, the measurement time can be shortened compared to the measurement method using the conventional VNA and switch matrix.”

 

5) Reviewer’s comment: Although the authors proposed a measurement system, however, the comparison in simulations is limited.

Author’s response: We appreciate the helpful comment. Our proposed antenna measurement system was verified through comparison with a general far-field measurement system and the planar near-field measurement system.

Author Response File: Author Response.pdf

Reviewer 3 Report

 

This article proposes the antenna measurement system, but there are similar measurement systems already on the market (for example, the StarLab 50 GHz by MVG). Authors not mentioned it in the article for any reason. 

The reference list has only 3 sources published in 2018, the rest of 22 are older. 

The paper was prepared carelessly. Some figures have poor quality and miss details. For variables used different fonts. 

 

Unfortunately, this article has no scientific novelty and value. 

Author Response

1) Reviewer’s comment: This article proposes the antenna measurement system, but there are similar measurement systems already on the market (for example, the StarLab 50 GHz by MVG). Authors not mentioned it in the article for any reason.

Author’s response: We appreciate the valuable comments. MVG's measurement system consists of a vector network analyzer and a switch matrix. However, our system uses a multi-channel digitizer so that each probe is composed of an independent channel. Thus, we can simultaneously measure vertical/horizontal data on all probes. Time can be significantly reduced compared to the conventional MVG measurement system that uses a switch matrix for each probe.

 

2) Reviewer’s comment: The reference list has only 3 sources published in 2018, the rest of 22 are older.

Author’s response: We appreciate the reviewer’s comment. Accordingly, a recent reference has been added.

3) Reviewer’s comment: The paper was prepared carelessly. Some figures have poor quality and miss details. For variables used different fonts.

Author’s response: We appreciate the reviewer’s comment. We updated the figures and document fonts as per your recommendation.

 

4) Reviewer’s comment: Unfortunately, this article has no scientific novelty and value.

Author’s response: We appreciate the reviewer’s comment. As mentioned earlier, unlike the existing multi-probe measurement system (MVG), it can simultaneously measure vertical/horizontal results from all probes by utilizing a multi-channel digitizer, which can dramatically reduce measurement time.

Author Response File: Author Response.pdf

Reviewer 4 Report

- Authors should add cross-polarization patterns in the 45 deg. phi plane since you already have V/H polarizations available.

- What about measurement of low-gain antennas ?

- Please specify the measurement speed and compare to standard spherical NF measurement

Line 154, improve format of F_smn

Author Response

1) Reviewer’s comment: Authors should add cross-polarization patterns in the 45 deg. phi plane since you already have V/H polarizations available.

Author’s response: We appreciate the reviewer’s comment. Accordingly, we added cross-polarization result.

 

2) Reviewer’s comment: What about measurement of low-gain antennas ?

Author’s response: We appreciate the reviewer’s comment. Low-gain 28 GHz planar patch antenna measurement results have been added. For near field measurement, if the gain is low, the directivity is weakened and the accuracy is lowered due to the influence of the measurement environment. However, the measurement accuracy can be improved by using a measuring jig.

3) Reviewer’s comment: Please specify the measurement speed and compare to standard spherical NF measurement

Author’s response: We appreciate the reviewer’s comment. In case of standard spherical near-field measurement system, it takes 580 minutes to measure 28 frequencies (26.5-40GHz) at intervals of 1 degree theta and phi. However, our proposed measurement system can measure in 25 minutes, improving the speed by more than 20 times.

 

4) Reviewer’s comment: Line 154, improve format of F_smn

Author’s response: We appreciate the reviewer’s comment. The format of the F_smn has been improved.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors have addressed my concerns, no further comments.

Author Response

Reviewer #2 :

1) Reviewer’s comment: The authors have addressed my concerns, no further comments.

Author’s response: We appreciate the reviewer’s comment. The comments helped us to understand the critical issues in this paper.

Author Response File: Author Response.pdf

Reviewer 4 Report

I have doubts about the Cross polar patterns of the horn (Fig. 10, 11), can you please add simulated results as well?

Author Response

Reviewer #4 :

1) Reviewer’s comment: I have doubts about the Cross polar patterns of the horn (Fig. 10, 11), can you please add simulated results as well?

Author’s response: We appreciate the reviewer’s comment. we shared simulated results(Using ANSYS HFSS).

Cross polarization measurement results are slightly different from simulations. The reason for the difference in results seems to be due to the structure of the multi-probe measurement system and anechoic chamber characteristics (XPD characteristics of broadband probe antenna, jig effect, multi-reflection effect, etc.).

The multi probe measurement system is designed to quickly measure the Co polarization characteristics of the AUT in priority. For AUTs that require accurate measurement of cross polarization, it is more advantageous to measure precisely in the far-field chamber than in the MPAC chamber.

 

Author Response File: Author Response.pdf

Round 3

Reviewer 4 Report

Thanks for addressing my comments.