MACKEY Q-Type Miniaturized Using Two Shorting
Plates
Koki Iijima(1), Keito Yokoe(1)，Shigeru Makino(1)，Kenji Itoh(1)(1) Kanazawa Institute of Technology, 7-1 Ogigaoka, Nonoichishi, Ishikawa, Japanb1813979@planet.kanazawa-it.ac.jp

Figure 1 shows the model diagram of the unbalanced
MACKEY II designed for the Wi-Fi 2 GHz band. The model
consists of three layers: a metal plate, an antenna plate, and agrid plate, with dielectric filling the gap between the plates. Gridplate (1) and metal plate (3) act as AMC substrates for workingon metal, and grid plate (1) and antenna plate (2) act as antenna
substrates for radiation (Figure 1). Figure 2 shows the voltage
standing wave ratio (VSWR) characteristics of this model. Thismodel works both in space and on metal (Figure 2).

Side view
(1)
(2)
(3)

t = 1.0

Feeding pointg

L = 2×g + s = 69.3

w=1

W = 30g = 34.4

s = 0.5(1) Grid plateℓ = 25.5

L = 69.3

II. DEVELOPMENT OF MACKEY Q-TYPE
The width, L, is a parameter that depends on the design
frequency, which is approximately λ/2. The model shown inFigure 1 has a width, L, of approximately 69.3 mm. In this paper,
we propose the MACKEY Q(Quarter wavelength)-type, aminiaturized version of the type shown in Figure 1.
The concept of miniaturization is illustrated in Figure 3. The
mirror image principle was used to miniaturize the antenna by
installing two shorting plates inside the unbalanced MACKEY
II. The antenna structure is a three-layer structure, similar to thatof the unbalanced MACKEY II, and it is supplied with powerfrom the antenna plate. The supplied power is transmitted
between the shorting plate and grid slits, and radio waves areradiated at the left and bottom edges of the grid plate. Because
the radio waves radiated from each side are orthogonal withequal amplitude and phase, the combined wave radiates alinearly polarized wave of φ = 135°, and the gain is 3 dBi greaterthan φ = 90°.

Feeding point(2) Antenna plate
Copper

Unit [mm]Fig. 2. VSWR characteristics of the unbalanced MACKEY IIZ(3) Metal plate

NPC-F260AYL≒λ/2(1)Grid plateXW≒λ/4

h = 2.0

2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
Frequency[GHz]In_free_space
On_metal

L≒λ/4

W≒λ/4

I. INTRODUCTION
The metasurface-inspired antenna chip developed by theKIT EOE laboratory (MACKEY) is a small antenna unaffectedby the surrounding metal [1]. MACKEY II, a thinner version ofMACKEY, was developed by inserting an antenna plate in theAMC substrate of MACKEY [2]. In addition, an unbalanced
MACKEY II with a single-port feed was developed using aninverted L-shaped antenna as the feed element of MACKEY [3].

10987654321VSWR

Abstract—The metasurface-inspired antenna chip developedby the KIT EOE laboratory (MACKEY) is a small antenna
unaffected by metal. In the paper, we propose a MAKCEY QType miniaturized to approximately λ/4 squared using two
shorting plates in the MACKEY.

Fig. 1. Model diagram of the unbalanced MACKEY II(2)Antenna plate
Feeding point

Feeding point

Fig. 3. Concept of miniaturization

III. ANALYSIS RESULTS
The analysis results of the MACKEY Q-type are presentedbelow. The analysis was performed using an electromagnetic
field simulator (Ansys HFSS) based on the finite element
method. A model diagram of the MACKEY Q-type used forthe analysis is shown in Fig. 4. The VSWR characteristics ofthe MACKEY Q-type and unbalanced MACKEY II in freespace and on metal are shown in Fig. 5(a) and 5(b),respectively. The radiation patterns at 2.45 GHz for cut planes
φ = 45° and 135° are shown in Fig. 6.

φ=45°(H plane)

φ=135°(E plane)
θ=0°

θ=0°

101000-10-10-2090°-20Z
Phi_in_free_space

90°YX

Theta_in_free_space
Phi_on_metal
Theta_on_metal(a) MACKEY Q-type

Fig. 5(a) and 5(b) show that the Q-type is narrower thanthe unbalanced type but works at 2.45 GHz in free space andon metal. Fig. 6(a) shows that the gain is 4.96 dBi in free spaceand 6.89 dBi on metal, indicating that the radiation is
sufficient in free space and on metal. A comparison of thefrontal gain (Fig. 6(a) and 6(b)) indicates that the Q-type is 1.5
dBi lower than the unbalanced type in free space and 0.92 dBilower on the metal. In terms of the antenna area, theMACKEY Q-type is approximately 70% of the unbalanced
MACKEY II. Hence, the antenna can be miniaturized without
much loss of gain.

XZ(H plane)
10 Z

YZ(E plane)
10 Z
00-10

-10-20Y-20

ZX

Phi_in_free_space

XZY

Theta_in_free_space
Phi_on_metal

XY

Theta_on_metal(b) Unbalanced MACKEY II
Fig. 6. Radiation pattern
IV. CONCLUSION
In this study, a compact MACKEY Q-type was developed
using two shorting plates in an unbalanced MACKEY II. The
miniaturization was based on a mirror image principle using ashorting plate. Based on the analysis results, the antenna
worked at 2.45 GHz, although the VSWR characteristics werenarrower than those of the unbalanced MACKEY II. The gainin the frontal direction was 4.96 dBi in free space and 6.89 dBi
on metal, indicating that the antenna radiated well. In addition,
the area of the MACKEY Q type could be miniaturized toabout 70% of that of the unbalanced MACKEY II.

Fig. 4. Model diagram of the MACKEY Q-type

443

VSWR

5VSWR

52211

ACKNOWLEDGMENTThis study was supported by JST CREST, Japan (Grant
Number: JPMJCR20Q1).
REFERENCES
[1]

32.3

2.4
2.5
2.6
Frequency[GHz]Q_typeUnbalanced_type(a)In free space

[2]
[3]
2.3

2.4
2.5
2.6
Frequency[GHz]Q_typeUnbalanced_type(b)On metal

Fig. 5. VSWR characteristics of the MACKEY Q-type andunbalanced MACKEY II

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., “MACKEY II with reduced thickness by using anew structure,” IEEE APS-2020, pp. 599-600, July 2020
K. Miyashita et al. “Feasiblity study of an unbalanced type R withenhanced robustness on metal,” in ISAP 2021, October 2021.