2022 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM), Narashino,Japan

Consideration of a One-Dimensional MACKEY
ArrayKiichi Wakayama
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoichi, Ishikawa, Japanb1849550@neptune.kanazawa-it.ac.jp

XZYg

g=35.1s/2=5①Grid plate

W=45.1w

Port 4Port 3

Port 2g

w=1wℓℓ

W=4×g + 4×s=180.4wℓ=28.8Port 2Feeding point

Port 3Port 4ws

L =2×g +2× s=90.2
Port 1w=1

s/2=5W =4×g + 4×s=180.4

s=10gggs/2gs①Grid plates/2ℓ②Antenna plate
Copper

NPC-F260A③Metal plate
R1661

Fig. 3. Model diagram of H-plane array

III. ANALYSIS RESULTS

L=2×g+2×s=90.2③Metal plate②Antenna plate
Copper
NPC-F260A

Fig. 1. Model diagram of MACKEY II

This work was supported by JST CREST (Grant Number
JPMJCR20Q1), Japan.

978-1-6654-3238-2/22/$31.00 ©2022 IEEE

Copper
NPC-F260A

L =2×g +2× s=90.2s①Grid plateℓ=28.8s/2

W= g + s=45.1

s/2

s=10s/2s/2
W= g + s=45.1

gs/2=5③Metal plate

Fig. 2. Model diagram of E-plane arrayg=35.1

Fig. 1 shows a model diagram of MACKEY II for the WiFi
2.4-GHz band used as the model for this study. In this study,
MACKEY II [2] was continuously arrayed in the electric andmagnetic field planes, as demonstrated in Figs. 2 and 3. "Eplane array" and "H-plane array" are models with continuous
arrays in the electric and magnetic field planes, respectively.
Four-element arrays were used for the E-plane and H-planearrays, and the dipole elements were arranged in the Zdirection. This study examined the differences in the directionof the element array. In addition, the element spacing wasverified as λ/4.
L=2×g+2×s=90.2

Port 1

R1661

II. CONSIDERATION OF ONE-DIMENSIONAL ARRAYgℓFeeding point

Recently, with advancements in the Internet of Things, themetasurface-inspired antenna chip developed by the KIT EOELaboratory (MACKEY) [1] has been established as a compact
antenna that is less susceptible to the influence of thesurrounding metal. This study investigated MACKEY
arraying to improve the gain and change directivity for
wireless power transmission, a technology that transmits
power wirelessly. MACKEY can be easily arrayed with anelement spacing of λ/4.

g=35.1②Antenna platew

W=45.1

Keywords—MACKEY II; WiFi 2.4 GHz; arrays/2ℓℓ
L =5×g + 5×s=225.5ℓ=28.8s/2

sss
L=5×g + 5×s=225.5

s=10s/2=5I. INTRODUCTION

ggg

g=35.1

W=45.1

Abstract— This study examined a compact and thinmetasurface-inspired antenna chip developed by the KIT EOELaboratory (MACKEY). It can operate in free space and onmetals. This study investigates the operation of MACKEY II
when it is continuously arrayed in the electric and magnetic field
directions.

wKenji Itoh
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoichi, Ishikawa, Japanitoh.kenji@neptune.kanazawa-it.ac.jp

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

w=1

Hajime Suzuki
Department of Electrical andElectronic Engineering
Kanazawa Institute of Technology
Nonoichi, Ishikawa, Japanb1845590@planet.kanazawa-it.ac.jp

23The analysis conditions assume an ideal power supplycircuit with equal amplitude and phase. The analysis software
used was HFSS from Ansys. Fig. 4 shows the loss for the Eplane and H-plane arrays for different slit widths (s). The Eplane array exhibited the highest actual gain and lowest
reflection loss when s was 10 mm. The H-plane array had thehighest actual gain and lowest reflection loss when s was 15mm, but the reduction in reflection loss was smaller than whens was 10 mm. Therefore, considering the area of the antenna,a slit width of 10 mm was used. Figs. 5 and 6 demonstrate theactual gain of the E-plane and H-plane arrays whensynthesized. The gains of the E-plane and H-plane arrays inthe frontal direction were 9.55 and 10.95 dBi, respectively.
The frontal gain of the H-plane array was higher than that of

2022 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM), Narashino,Japangain obtained from 4πS/λ^2 using the area S, the aperture
efficiencies of the E-plane and H-plane arrays were 102.61%
and 83.50%, respectively, indicating that sufficient gain wasobtained. The formula 4πS/λ^2 was originally used when theantenna diameter was sufficiently larger than λ. Consequently,
the aperture efficiency can exceed 100%.

the E-plane array because the antenna area of the former wasgreater than that of the latter. Considering the conventional
MACKEY II, the gain on the metal was greater than that infree space.
4109988721VSWR

107VSWRLoss [dB]300510Slit width s [mm]156655443322

12.2

1

H Reflection Loss
E Reflection Loss

2.2

H Dielectric Loss and Conductor LossXYMACKEYⅡ

151050-5-10-15-20

H-plane array

2.4
2.5
Frequency [GHz]

XY

2.4
2.5
Frequency [GHz]

2.6

2.7

on metal(b) E-place array

Fig. 7. Measured VSWR characteristics

Z

151050-5-10-15-20XX

151050-5-10-15-20YZX

H-plane array

E-plane array

E-plane array

151050-5-10-15-20

2.3

2.7(a) H-place array

Fig. 8. Measured radiation pattern in free space

Fig. 5. Analysis of radiation pattern in free space
151050-5-10-15-20

2.6freeE Dielectric Loss and Conductor LossFig. 4. Comparison chart for each loss
151050-5-10-15-20

2.3151050-5-10-15-20ZXX

151050-5-10-15-20Y

E-plane array

ZX

H-plane array

Fig. 9. Measurement radiation pattern on metal

MACKEYⅡ

H-plane array

E-plane array

V. CONCLUSIONS.

Fig. 6. Analysis of radiation pattern on metal

This study investigated continuous MACKEY II arrays in
the electric and magnetic field directions. The E-plane and Hplane arrays had a higher gain and sharper directivity than theconventional MACKEY. The gain in the frontal direction washigher for the H-plane array. The gains of the E- and H-planearrays were compared with the gain calculated from 4πS/λ^2,and the gain was observed to be sufficient.

IV. MEASUREMENT RESULT
Fig. 7 demonstrates the voltage standing wave ratio(VSWR) characteristics, which are well within the WiFi 2.45GHz frequency band. No significant change was observed
between the free space and metal, indicating that the device
works on metal as well. Figs. 8 and 9 illustrate the radiation
pattern of the composite array. Closer to the analytical values,
the gains in the frontal direction for the E-plane and H-planearrays were 9.51 and 10.61 dBi, respectively. On metal, the Eplane and H-plane arrays exhibited gains of 10.61 and 10.90
dBi, respectively, which were similar to the analytical values
and higher than the free space values. The cause of the error
in the analytical value is considered to be the phase difference
and distributor loss used in the measurement. When themeasured gain in the frontal direction was compared with theREFERENCES[1][2]

24T. Moroya et al., “AMC inspired small antenna MACKEY,”
IEICE. Trans. Commun, vol. J99-B, no. 9, pp. 786–794, Sep. 2016.
K. Miyashita, S. Makino, and K. Itoh, “Feasibility study of an
unbalanced MACKEY type R with enhanced robustness on metal,” inISAP 2021, October 2021.