A Compact Semi-Circular and Arc-Shaped Slot Antenna for Heterogeneous RF Front-Ends

Round 1

Reviewer 1 Report

This paper presents a compact microstrip dual-band antenna. Various parametric studies, simulation as well measurement results are presented. Given that there exist several antennas with similar properties in the relevant literature, I believe that the paper needs to be further improved, in order to be of interest for the journal's audience.
- The Introduction needs to be improved. It is customary to mention the main content and the key contributions of the paper in the Introduction.
- Regarding Fig. 2 and the pertinent comparison: I believe that it is not a fair comparison, as no optimization has been performed for first two individual structures. In fact, the first one appears to be a simple transmission line, and no satisfactory radiation properties should be expected anyway.
- It is not clear what the purpose of the equivalent model in sub-section 2.2 is.
- How are the current paths in Fig. 10 determined? In addition, I cannot see any difference between the paths of the two sub-figures.
- As the authors state, "the cross polarization is quite important" under certain conditions. Is that a desirable attribute?
- Unlike the S11 measurement, it is not mentioned how the gain of the antenna is measured.
- Does the comparison in Table 1 clearly show that the proposed antenna provides additional advantages or features?
- The following need to be corrected: "The -10 dB 20 impedance bandwidth covers the 1.8 GHz and 2.4 GHz bands is accomplished" in the Abstract, "most potential candidates" in the Introduction, "hole structure" in Section 2, "Fats" in Fig. 14a.

Author Response

Comments and Suggestions of Reviewer1: This paper presents a compact microstrip dual-band antenna. Various parametric studies, simulation as well measurement results are presented. Given that there exist several antennas with similar properties in the relevant literature, I believe that the paper needs to be further improved, in order to be of interest for the journal's audience.

Thanks for the careful reading.

Indeed, several antennas exist, but our structure is well improved compared to those available in the literature. This is presented in the comparative table Tab.1 after a comparison with 23 antennas.

We updated the manuscript by: “Let us conclude this part with a comparison of the size, operating bands and gain of our antenna with those realized or simulated available in the literature. It is clear from Table 1 that our proposed structure presents a good compromise between miniaturization and the significant gain obtained compared to the reported studies. Our antenna structure is well miniaturized and has the best ratio gain / size. By comparing with higher gain antenna cases, close to ours, presented in [2] [5] [6] [17] [23] [44], our proposed antenna size is reduced by more than three times. However, for reported antennas with size close to ours [3] [30] [45] [46] [9] [10] [13] [18] [26], the proposed antenna presents a higher gain.”

and this may be considered as a novelty.

The Introduction needs to be improved. It is customary to mention the main content and the key contributions of the paper in the Introduction.

Thank you for this comment. The introduction is improved

We updated by:

“In this paper, we present the technique of introducing small arc-shaped slots in the antenna structure to realize a new high gain miniaturized dual-band radiating antenna. The antenna design consists of two main semi-circular slots. Two adjunct small arc-shaped slots are asymmetrically and partially etched round these two main slots to realize the dual-band function and obtain a small sized-structure. The antenna is fed by a stubbed microstrip line for a better impedance matching in the operating bands. The proposed slot antenna covers the desirable 1.8 GHz and 2.4 GHz bands for hand-held devices and medical applications.”

Regarding Fig. 2 and the pertinent comparison: I believe that it is not a fair comparison, as no optimization has been performed for first two individual structures. In fact, the first one appears to be a simple transmission line, and no satisfactory radiation properties should be expected anyway.

Actually this is not for the purpose of noticing optimization but rather to define the effect of each element in the design. Your comment is taken into consideration: the first structure is removed and required changes are done.

It is not clear what the purpose of the equivalent model in sub-section 2.2 is.

In order to analyze the true behavior of the system, co-simulation of the antenna and other RF front-end components is necessary. It is necessary to draw the equivalent circuit model of the antenna, because time domain simulators such as Advanced Design System (ADS) and SPICE are used for majority of the RF front-end design

How are the current paths in Fig. 10 determined? In addition, I cannot see any difference between the paths of the two sub-figures.

They are measured using HFSS tools

Figure 10 corrected

As the authors state, "the cross polarization is quite important" under certain conditions. Is that a desirable attribute?

it is very weak in the E, H planes, and is slightly higher in YZ plane

We updated the manuscript by: “Whereas, for the YZ plane, the cross polarization is slightly higher.”

Unlike the S11 measurement, it is not mentioned how the gain of the antenna is measured.

The measured gains of the prototype were carried out in a far-field anechoic chamber using a calibrated EMCO type 3115 broadband horn as the reference antenna. The reference fixed antenna was a broadband horn (EMCO type 3115) positioned at 4 m from the antenna under test. We have scanned for three orthogonal planes. For each plane a co-polar and cross-polar gain components were measured.  

Does the comparison in Table 1 clearly show that the proposed antenna provides additional advantages or features?

Among the 23 references of Tab.1, we can see that our antenna is better. It is miniaturized with a considerable gain over all reported antennas. And we have shown that ours has the best compromise between gain and size.

We updated the manuscript by: “Our antenna structure is well miniaturized and has the best ratio gain / size. By comparing with higher gain antenna cases, close to ours, presented in [2] [5] [6] [17] [23] [44], our proposed antenna size is reduced by more than three times. However, for reported antennas with size close to ours [3] [30] [45] [46] [9] [10] [13] [18] [26] our antenna presents a higher gain.”

The following need to be corrected: "The -10 dB 20 impedance bandwidth covers the 1.8 GHz and 2.4 GHz bands is accomplished" in the Abstract, "most potential candidates" in the Introduction, "hole structure" in Section 2, "Fats" in Fig. 14a.

Corrections done

We updated the manuscript by:

“An impedance bandwidth, for S₁₁<-10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished,” “is one of the most promising candidates” “whole structure” Fat

Author Response File: Author Response.pdf

Reviewer 2 Report

The proposed method is interesting. Reviewer has following two comments:

Author Response

Comments and Suggestions of Reviewer2

The proposed method is interesting.

Thanks for the careful reading.

Abstract is required to improve. 

done

Motivation and novelty are not clearly described in the Introduction Section.

Paragraph added for comparison

We updated by:

“In this paper, we present the technique of introducing small arc-shaped slots in the antenna structure to realize a new high gain miniaturized dual-band radiating antenna. The antenna design consists of two main semi-circular slots. Two adjunct small arc-shaped slots are asymmetrically and partially etched round these two main slots to realize the dual-band function and obtain a small sized-structure. The antenna is fed by a stubbed microstrip line for a better impedance matching in the operating bands. The proposed slot antenna covers the desirable 1.8 GHz and 2.4 GHz bands for hand-held devices and medical applications.”

Author Response File: Author Response.pdf

Reviewer 3 Report

In the proposed manuscript authors are presenting a new design of a compact semi-circular dual-band antenna. The design of the antenna is microstrip slot, with dimensions of 30x28.5x0.8mm. The design of the antenna was simulated and optimized with High Frequency Structure Simulator (HFSS). The antenna covers 1.8GHz and 2.4GHz band width -10dB return loss and is therefore especially suitable for hand-held devices and medical applications. Other frequency bands are possible by simply changing one of the geometrical antenna dimensions. Authors state that the antenna has a stable radiation pattern as well.

The manuscript is well organized and well written. The language is good, and it reads fluently.

Some minor comments/suggestions:

Abstract, Line 19, 20, 21: “The -10 dB impedance bandwidth covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications.” -> This sentence is a bit unclear. Please correct. Also, -10dB is not impedance or bandwidth, please correct.

Line 55-56: “Slot antennas allow bidirectional radiation which makes them advantageous over patch antennas with a larger bandwidth characteristic.” -> Patch antennas are usually designed to have directional gain.

Figure 2, a: A strip over ground is not considered as an antenna, so I would not call it that.

Line 104: “Moreover, antenna (b) exhibits a very poor gain.” – The direction is important. Try to flip the strip from left to right.

Figure 4: The labels of axes are poorly visible. Please make them more

Figure 6.a: The parameter X1 should be labeled as ratio 1:1.025.

Figure 11: The y-axes are missing units.

Author Response

III. Comments and Suggestions of the Reviewer3

In the proposed manuscript authors are presenting a new design of a compact semi-circular dual-band antenna. The design of the antenna is microstrip slot, with dimensions of 30x28.5x0.8mm. The design of the antenna was simulated and optimized with High Frequency Structure Simulator (HFSS). The antenna covers 1.8GHz and 2.4GHz band width -10dB return loss and is therefore especially suitable for hand-held devices and medical applications. Other frequency bands are possible by simply changing one of the geometrical antenna dimensions. Authors state that the antenna has a stable radiation pattern as well.

The manuscript is well organized and well written. The language is good, and it reads fluently.

Thanks for your careful reading

Abstract, Line 19, 20, 21: “The -10 dB impedance bandwidth covers the 1.8 GHz and 2.4 GHz bands is accomplished, which makes the proposed antenna basically suitable for hand-held devices and medical applications.” -> This sentence is a bit unclear. Please correct. Also, -10dB is not impedance or bandwidth, please correct.

Corrected

We updated by:

“An impedance bandwidth, for S₁₁<-10 dB, that covers the 1.8 GHz and 2.4 GHz bands is accomplished,”

Line 55-56: “Slot antennas allow bidirectional radiation which makes them advantageous over patch antennas with a larger bandwidth characteristic.” -> Patch antennas are usually designed to have directional gain.

Thank you for your remark, the sentence is rephrased

We updated by:

Slot antennas allow bidirectional radiation which makes them advantageous over patch antennas with a larger bandwidth characteristic

“Generally speaking, slot antennas have larger bandwidth (BW) than the microstrip antennas because of their lower quality factors due to the bidirectional radiation characteristics [4] [35].”

Figure 2, a: A strip over ground is not considered as an antenna, so I would not call it that.

Structure omitted

Line 104: “Moreover, antenna (b) exhibits a very poor gain.” – The direction is important. Try to flip the strip from left to right.

Thanks for the suggestion

By this step we aimed to examine the effect of the slots and arcs each alone and all together and not rather a step of optimization, however, this suggestion may be of interest for future work.

Figure 4: The labels of axes are poorly visible. Please make them more

Labels of axes in Figure 2 and 4 have been clearly shown

Figure 6.a: The parameter X1 should be labeled as ratio 1:1.025.

Corrected

Figure 11: The y-axes are missing units.

It is a normalized radiation pattern

We updated by:

“Figure 11. Normalized radiation pattern at (a) 1.8 and (b) 2.4 GHz”

Author Response File: Author Response.pdf