Study on the two-dimensional array of MACKEY IIHajime Suzuki (1), Kaisei Tsuji (1)，Shigeru Makino(1)，Kenji Itoh(1)(1) Kanazawa Institute of Technology, 7-1 Ogigaoka, Nonoichishi, Ishikawa, Japanb1845590@planet.kanazawa-it.ac.jp
Abstract— A compact and thin antenna metasurface-inspired
antenna chip developed by the KIT EOE Laboratory (MACKEY)
that can operate both in free space and on metal is proposed in thisstudy. Here, the examined the difference in performance of theMACKEY II two-dimensional array model by changing theelement spacing between λ/4 and λ/2.
I. INTRODUCTIONZIn recent years, MACKEY (meta-surface-inspired antenna
chip developed by KIT EOE Laboratory, hereinafter referred toas "basic type")[1] has been investigated as a compact antennathat is less affected by the surrounding metal owing to the rapid
spread of IoT. In this study, MACKEY arraying wasinvestigated to improve the gain and change the directivity
through arraying.
II. STUDY OF MACKEY TWO DIMENSIONAL ARRAY
Figure 1 shows the model diagram of MACKEY II [2] forthe 2.4 GHz band Wi-Fi used as a model for this study. Here,MACKEY II was arranged in two dimensions, as shown in Fig.
2, and the element spacing was set to λ/4 and λ/2. The λ/4element spacing results in a 9-element array, while the λ/2
spacing gives a 4-element array. The dipole elements, which are
the feed antennas, were arranged in the Z-direction. Figure 3
shows an array of dipole elements. In the case of the λ/4 element
spacing, the dual polarization sharing of two elements × fourelements in the Y-direction is possible. In this study, weverified the differences in the element spacing.
L=2×g + sLgg

t=2gℓ(2)Antenna plate
Unit [mm](3)Feeding point
Side view(3)Metal plate
Copper(2)

tt=1

s=5(1)Grid plate

(1)

h=1

NPC-F260A

Figure 1. Model diagram of MACKEY
X

L=3×g+2×s

L=3×g+2×s

Ztt

Y

Figure 2. Two-dimensional array model diagramX

port11

port12

port13

port21

port22

port23

port32

port31

port1

port2

port3

port4

port33

Y(a) Element spacing λ/4(b) Element spacing λ/2.

Figure 3. Array of dipole elements

III. EXAMINATION OF THE ANALYSIS RESULTS
Figures 4 and 5 show the Voltage Standing Wave Ratio (VSER)
characteristics of the element spacing λ/4 and λ/2 when poweris supplied to each port. For symmetry reasons, only ports 11,12, 21, and 22 are shown for the element spacing λ/4, and only
port 1 for the element spacing λ/2. The analysis conditions
assume an ideal power supply circuit with equal amplitude andphase, and the power is supplied directly to the dipole elementof the antenna plate, as shown in Fig. 1 (2). In the model withλ/4 element spacing, the antenna length ℓ of 37.8 mm and thegrit width g of 36.59 mm satisfy the operating frequency range.
In the case of the model with λ/2 element spacing, the antenna
length ℓ is 30.8 mm and the grit width g is 35.95 mm. Figures
6 and 7 show the comparison graphs of the frequency gain andthe calculated gain. The definition of different “Gains” is asfollows:
・Directivity: Gain is determined by the radiation pattern anddoes not include dielectric loss, conductor loss, or reflection
loss.
・Gain: Gain does not include dielectric loss, and conductor
loss, but just reflection loss.
・Realized gain: The gain includes dielectric loss, conductor
loss, and reflection loss.
ସగௌ・Ideal gain: The gain obtained from the formula మ using theఒarea S
From the Fig.6,Fig7 when the element spacing is λ/4, the real
gain is closest to the ideal gain, and when the element spacingis λ/2, the actual gain is closest to the ideal gain, both of which
are calculated from the area around 2.4 GHz. However, the gain
tends to decrease around 2.5 GHz, which is believed to bebecause of the decrease in the gain in the frontal direction
caused by an increase in the beam width. Figures 8 and 9 show
the synthesized radiation patterns. From the figures, it can beconcluded that the arraying is effective because the beam widthis narrower for both λ/4 and λ/2 element spacing. The gain ishigher in the forward direction because the back lobe of theelement spacing λ/4 is smaller than that of the element spacing
λ/2.
1010

9

977

port11
port12
port21
port22

65

VSWR

VSWR

X

100-10-20

YZX

885
43

32

21

1

22.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9Frequency[GHz]port11
port12
port21
port226423free2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9Frequency[GHz]3100-10-20(b) Metal.

Figure 4. VSWR characteristics of element spacing λ/410109988

port165432211
Frequency[GHz]3free2

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9(a) Free

Frequency[GHz]X3on metal

Figure 9. Radiation pattern of Element spacing λ/2(b) Metal.

Figure 5. VSWR characteristics of element spacing λ/2IV. SUMMARY
MACKEY two-dimensional arrays with different element
spacing values were investigated. There was no significant
difference in the gain between the λ/4 and λ/2 spacing. In thecase of the λ/4 element spacing, a dual-polarization shared arraycan be realized by arranging 2 × 4 dipole elements in the Ydirection.

2015Gain[dBi]Z

53

2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9

Y100-10-2064

105022.2

2.4

2.6

2.8

3

Frequency[GHz]DirectivityGain

Realized Gain

Ideal Gain

Figure 6. Gain diagram for element spacing λ/4

ACKNOWLEDGMENT
This work was supported by JST CREST, Grant Number
JPMJCR20Q1, Japan.
REFERENCES

20[1] T.MOROYA et al., “AMC Inspired Small Antenna MACKEY,”
IEICE. Trans. Commun, vol. J99-B, no. 9, Sep. 2016, pp. 786794[2] K.MIYASHITA et al., “MACKEY II with reduced thickness by using a
new structure,” IEEE APS-2020, Jul.2020, pp.599-600

15Gain[dBi]2X

port17VSWR

7on metal

Figure 8. Radiation pattern of Element spacing λ/4(a) FreeVSWR

100-10-20

10502

2.2

2.4

2.6

2.8

Frequency[GHz]Directivity

Gain

Realized Gain

Ideal Gain

Fig.7 Gain diagram for element spacing λ/23