978-1-6654-7962-2/22/$31.00 ©2022 IEEE

A Feasibility Study of Circularly Polarized
MACKEY Using Sequential Array Technique
Michinori Yoneda
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanb1812587@planet.kanazawa-it.ac.jp

Keito Yokoe
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanb1995149@planet.kanazawa-it.ac.jp

Shigeru Makino
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanmakino@neptune.kanazawa-it.ac.jp

Kenji Itoh
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanitoh.kenji@neptune.kanazawa-it.ac.jp

Koki IiJima
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanb1813979@planet.kanazawa-it.ac.jp

HaJime Suzuki
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoiti, Isikawa, Japanb1845590@planet.kanazawa-it.ac.jp

Abstract— This study aimed to convert linear convectionalpolarization to circular polarization using an unbalanced
metasurface-inspired antenna chip developed by the KIT EOELaboratory (MACKEY). We aimed to achieve a Voltage
Standing Wave Ratio (VSWR) of less than three and axial ratioof less than 3 dB in free space and on metal at 2.4–2.5 GHz. For
this purpose, we proposed a circularly polarized MACKEY C4
sequential type using sequential array technology. We achieved
our goal by optimizing the slit width.

which is used in Wi-Fi 2GHz. The model in Fig. 1 shows theoptimal design values considering slit width.
.

Keywords— MACKEY, Circular Polarization, 2.45 GHzI. INTRODUCTION
The metasurface-inspired antenna chip developed by theKIT EOE Laboratory (MACKEY) [1] was devised as a robust
antenna that is unaffected by surrounding metals. In this study,
we proposed a new model, MACKEY C4 sequential type
(hereinafter referred to as "MACKEY CS"), based on
MACKEY II [2], which is a thinner version of MACKEY anduses an inverted L element for an unbalanced power supply
along with four grid plates to change the polarization fromconventional linear to circular.

(a) Linear polarization MACKEY ⅡII. PROPOSAL FOR MACKEY CSFig. 1 shows a diagram of MACKEY II radiating linearlypolarized waves and MACKEY CS radiating circularly
polarized waves. MACKEY CS is a sequential array of four
MACKEY II chips fed to four feeding points with equal
amplitude and phase differences of 0°, 90°, 180°, and 270°,
respectively [3]. The size of a normal antenna is 1 λ square
when converted into a sequential array. However, as shownin Fig. 2, MACKEY CS shares a grid plate; therefore, it
radiates circularly polarized waves with an antenna size ofλ/2 square. As a result, it is possible to radiate circularly
polarized waves with an antenna size that is 1/4 of the usualsize.
In this study, we evaluated the radiated gain and therelative bandwidth satisfying a voltage standing wave ratio(VSWR) of 3 or less and an axial ratio of 3 dB or less in freespace and on metal when the center frequency was 2.45 GHz,(b) Circular polarization MACKEY CS.
Fig. 1. Model diagram of antenna

Fig. 2. Shared grid plate

This work was supported by JST CREST (grant number
JPMJCR20Q1), Japan.

479

III. EXAMINING OF MACKEY CS

IV. ANALYSIS RESULTS FOR MACKEY CS

In this study, to investigate the possibility of circularpolarization using MACKEY CS, power feeding wasperformed under ideal conditions of equal amplitude andphase differences of 0°, 90°, 180°, and 270°, respectively.
The analysis was performed using an electromagnetic
simulator (ANSYS, HFSS) based on the finite element
method.
The effects of the slit width were also examined by varying
the slit width. Fig. 3 shows the change in the maximum valueof the axial ratio between 2 and 3 GHz, and the relative
bandwidth of the VSWR when the slit width was varied. The
axial ratio does not change at any slit width and is almost zero
between 2 and 3 GHz, which is the ideal value. The relative
bandwidth of the VSWR widened as the slit width decreased.
Fig. 4 shows the change in the realized gain of the main andcross polarization in the frontal direction (x-axis direction
shown in Fig. 1) at 2.45 GHz when the slit width was varied.
The realized gain of the main polarization increases when theslit width increases. Fig. 5 shows the change in radiation
efficiency at 2.45 GHz and the antenna size when the slit
width is varied. Fig. 5 shows that the radiation efficiency
remains the same and the antenna size increases when the slit
width is increased, suggesting that the reason for the increasein the realized gain of the main polarization is the antennasize.

From the slit-width study, the analysis was performed on amodel with a slit width of 1 mm, as shown in Fig. 1. Fig. 6shows the axial ratio characteristics and VSWR in free spaceand on metal. The axial ratio characteristic is close to the ideal
value of 0 at all frequencies, both in free space and on metal.
The relative bandwidth of the VSWR, where the VSWR isless than 3, is 6.19 in free space and 6.16 on metal, indicatinga wide bandwidth. Fig. 7 shows the radiation patterns in freespace and on metal. The realized gain in the frontal direction
in free space is 6.76 dB and the realized gain in the frontal
direction on metal is 7.87 dB. The realized gain of the mainpolarization is maximum in the frontal direction, while therealized gain of the cross polarization is small.

2slit[mm]in_free_space34

XZ Plane
10 Z00-10-10Y-20
1on_metal

2slit[mm]in_free_space

0-10 132-20X

4

LHCP_in_free_space
RHCP_in_free_space
LHCP_on_metal
RHCP_on_metal

on_metal

3

LHCP_in_free_space
RHCP_in_free_space
LHCP_on_metal
RHCP_on_metal

Fig. 7. Radiation pattern4

realized gain of mainpolarization[dB]realized gain of crosspolarization[dB]-20-30V. CONCLUSION-40-50-60-70

123slit[mm]in_free_space
on_metal

4slit[mm]in_free_space
on_metalFig. 4. Change in realized gain of main and cross polarization when the slit
width is varied
1.00800.9575antenna size[mm]Radiation Efficiency

VSWR

Axial Ratio[dB]Fig. 6. Axial ratio and VSWR

Fig. 3. Change in the maximum value of the axial ratio and relative
bandwidth of the VSWR when the slit width is varied
1098765432
102.3 2.35 2.4 2.45 2.5 2.55 2.6Frequency[GHz]in_free_space
on_metal

XY Plane10 Xrelative band with of VSWR

1109876543212.3 2.35 2.4 2.45 2.5 2.55 2.6Frequency[GHz]in_free_space
on_metal

1098765432
10

Axial Ratio[dB]

1098
7654
32
10

10
98
7654
3
2
10

0.90
0.85
0.80
0.75
0.70

REFERENCES

70
65
60

[1]

55[2]

50
12slit[mm]in_free_space3
on_metal

4This paper presents a feasibility study of a new model forradiating circularly polarized waves from linearly polarizedwaves, an aspect that has been studied previously. The study
confirmed that circularly polarized waves are radiated withan antenna size of λ/2 square.
. In the future, simpler ways to feed power could beinvestigated, such as using two feeding points.

1

2

3

4

slit[mm]Fig. 5. Change in radiation efficiency and antenna size when the slit widthis varied

[3].

480

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