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

Dual-Frequency Sharing in MACKEY Q TypeKoki Iijima
Electrical and Electronic Engineering
Kanazawa Institute of Technology
Nonoichishi, Ishikawa, Japanb1813979@planet.kanazawa-it.ac.jp

Keito Yokoe
Electrical and Electronic Engineering
Kanazawa Institute of Technology
Nonoichishi, Ishikawa, Japanb1995149@planet.kanazawa-it.ac.jp

Shigeru Makino
Electrical and Electronic Engineering
Kanazawa Institute of Technology
Nonoichishi, Ishikawa, Japanmakino@neptune.kanazawa-it.ac.jp

Kenji Itoh
Electrical and Electronic Engineering
Kanazawa Institute of Technology
Nonoichishi, Ishikawa, Japanitoh.kenji@neptune.kanazawa-it.ac.jp

Abstract—The meta
surface-inspired antenna chipdeveloped by KIT EOE Laboratory (MACKEY) is a small
antenna that is unaffected by metal. The MACKEY Q type wasdeveloped based on MACKEY. It was miniaturized to a squarewith λ/4 on a side. This article proposes an antenna that canradiate radio waves of two polarizations with different desired
frequencies by varying the design parameters of the antenna.

5VSWR

432Keywords—MACKEY, metasurface-inspired antenna, twopolarizations, λ/4 squared

1I. INTRODUCTION

2.3

The metasurface-inspired antenna chip developed by theKIT EOE Laboratory (MACKEY) is a small antenna thatremains unaffected by the surrounding metal [1]. The
MACKEY II unbalanced type, which is a thinner version ofMACKEY that uses an inverted L-shaped antenna as afeeding element for an unbalanced power supply, was also
developed [2]. The MACKEY Q type was developed basedon the MACKEY II unbalanced type [3]. It was miniaturized
to a square with a side length of λ/4 by using two shortingplates.

2.4
2.5
Frequency [GHz]In free space
On metal

2.6

Fig. 2. VSWR characteristics of the MACKEY Q

II. PROPOSED DUAL-FREQUENCY SHARED MACKEY Q
A. Principle of MACKEY Q
The principle of the MACKEY Q system is discussed
below. Power is supplied from the second layer of the antenna
plate, and the supplied power is transmitted between theshorting and grid plates. Ratio waves are radiated at the left
and bottom edges of the grid plate. Because the radio waves
radiating from each side are orthogonal with equal amplitudes
and phases, the combined wave radiates a linearly polarizedwave of φ = 135°, and the gain is 3 dB greater than that at φ =90°, where φ is the angle of rotation along the x-axis.

Fig. 1 shows the model diagram of the MACKEY Q-type
designed for the Wi-Fi 2-GHz band. The model consists ofthree layers, namely, metal, antenna, and grid plates, with adielectric filling the gap between the plates. The grid plate (a)and metal plate (c) act as artificial magnetic conductor
substrates for working on the metal, and the grid plate (a) andantenna plate (b) act as antenna substrates for radiation (Fig.
1). Fig. 2 shows the voltage standing wave ratio (VSWR)
characteristics of this model. This model works in both freespace and on metal (Fig. 2).

B. Design Method for Dual Frequency
Based on the operating principle described above, theMACKEY Q-type radiates a linearly polarized wave at anoblique angle of 45° by combining vertical and horizontal
polarizations. Therefore, different frequencies can beresonated at the two polarizations by varying the length W andwidth g of the grid plate. Furthermore, varying the length andwidth of the grid plate create a difference in the distance ofthe transmission line from the feeding point to the left andbottom edges of the grid plate. Consequently, the feeding
element in the MACKEY Q-type for oblique 45° linear
polarization, which was installed in the upper-right corner,must be shifted slightly to equalize the distance of thetransmission lines.
III. ANALYSIS RESULTS
The results of the analysis of the dual-frequency shared
MACKEY Q-type are discussed below. The analysis wasperformed using an electromagnetic field simulator (ANSYSHFSS) based on the finite element method. The modelFig. 1. Model diagram of the MACKEY Q
JST CREST, Japan (Grant Number: JPMJCR20Q1)

978-1-6654-3238-2/22/$31.00 ©2022 IEEE118

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

10

diagram used for the analysis is shown in Fig. 3. W, g, ℓ, andℓℓo are frequency-dependent design parameters. Specifically,W and G are adjusted so that the resistance is 50 Ω at thedesired frequency by varying W and G, and the reactance isadjusted to 0 Ω by varying l. ℓℓo is a parameter to facilitate
matching by distributing the power equally between the twofrequencies. W and g are the length and width of the grid plate,respectively, ℓ is the length of the feeding element, and ℓℓo is
the position of the feeding element. In this study, one
frequency was fixed at 2.45 GHz, and the other was varied atfour points in the range of 2–3 GHz. The design parametersof the four models are presented in Table I. The VSWR
characteristics in free space and on metal for the four models
listed in Table I are illustrated in Figs. 4(a) and 4(b),respectively. Fig. 5 demonstrates the radiation patterns ofmodel 1 at 2.10 and 2.45 GHz with cut planes φ = 0° and φ =90°.

98VSWR

7654
3212

2.1

2.2

2.10–2.45

2.3 2.4 2.5 2.6 2.7 2.8 2.9Frequency [GHz]2.25–2.45 2.45–2.65 2.45–2.80

3(b) On metalFig. 4. VSWR characteristics of each model

φ = 90°φ = 0°
102.10 GHz

1000-10-10-20ZθYφX-20

Bird’s eye view
102.45 GHz

1000-10-10-20-20Phi in free space
Theta in free space
Phi on metal
Theta on metal

Fig. 3. Model diagram of the dual-frequency shared MACKEY Q
Fig. 5. Radiation pattern of model 1
DESIGN PARAMETERS PER FREQUENCYTABLE I.

Frequency

Wgℓℓoℓ

[GHz]

[mm]

[mm]

[mm]

[mm]

Model 12.10 & 2.45

35.5

41.9

2.95

15

Model 22.25 & 2.45

35.7

38.9

1.35

16.5

Model 32.45 & 2.65

32.9

35.6

1.1

16.1

Model 42.45 & 2.80

30.9

35.5

2.05

15.5

Fig. 4(b) shows that the proposed antenna works on metal,
although it is slightly shifted to the high-frequency sidecompared with that in Fig. 4(a). Fig. 5 illustrates that therealized gain in the frontal direction is 4.3 dBi in free space,6.03 dBi on metal at 2.10 GHz, and 5.25 dBi in free space and7.43 dBi on metal at 2.45GHz. It is clear that both frequencies
radiate sufficiently.

IV. CONCLUSION
In this study, we developed an antenna that radiates radio
waves of different frequencies in two polarizations by varying
the length and width of the grid plate in the first layer of theMACKEY Q-type. ℓℓo is an important design parameter forchanging the position of the feeder elements because
modifying the size of the grid plate causes differences in thelength of the transmission line. The analysis results
demonstrate that the model operates at the desired frequency,
both in free space and on metal, radiating sufficiently in thefrontal direction. Future plans include examining thefeasibility of implementing this model at other frequency
bands.

1098VSWR

765432122.1

2.2

2.10–2.45

2.3 2.4 2.5 2.6 2.7 2.8 2.9Frequency [GHz]2.25–2.45 2.45–2.65 2.45–2.80

3REFERENCES[1](a) Free space
[2]
[3]

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T. Moroya et al., “AMC inspired small antenna MACKEY,” IEICE
Trans. Commun., vol. J99-b, no. 9, pp. 786–794, September 2016. K.
Miyashita et al., “Feasibility study of an unbalanced type R withenhanced robustness on metal,” in ISAP 2021, October 2021.
Iijima et al., “MACKEY Q-Type Miniaturized Using Two ShortingPlates,” in IEEE AP-S/URSI 2022, (to be presented)