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

Scanning Spot Beam Reflectarray Antenna Study
Yusuke Kaimori
Kanazawa Institute of Technology
7-1 Ogigaoka, Nonoichishi,
Ishikawa 921-8501, Japanb1714005@planet.kanazawa-it.ac.jp

Shigeru Makino
Kanazawa Institute of Technology
7-1 Ogigaoka, Nonoichishi,
Ishikawa 921-8501, Japanmakino@neptune.kanazawa-it.ac.jp

Masayoshi Takao
Kanazawa Institute of Technology
7-1 Ogigaoka, Nonoichishi,
Ishikawa 921-8501, Japanb1833012@planet.kanazawa-it.ac.jp

properties: covering a 360° reflection phase-control area andhaving independent phase control.

Abstract— By combining the characteristics of a reflectarray
antenna to change the beam direction according to thefrequency and polarization, conventional multi-spot and multiscanning beams using a single reflector have been proposed. We
have previously shown the design method and analysis results ofscanning spot beams whose beam direction is changed byfrequency in the elevation direction and by polarization in theAzimuth direction. In this study, the measurement results of thescanning spot beam reflectarray antenna fabricated from thedesigned values are presented.
Keywords—reflectarray, scanning spot beam, frequency,
polarization

I. INTRODUCTION
In a multibeam communication system using reflectarray
antennas, a service area can be covered using a few mirror
planes by changing the beam direction according to thepolarization and frequency [1][2][3]. In this study, themeasurement results of the scanning spot beam reflectarray
antenna fabricated from the designed values are presented.

Fig. 2. Primary radiator position

III. ELEMENT DESIGN
Fig. 3 shows the linear element employed to change thephase according to the reflectarray polarization [4][5][6].

II. SCANNING SPOT BEAM
This study aims to achieve an efficient coverage of thedesired service area using a scanning spot beam. Fig. 1 shows
the arrangement of the primary radiators. Primary radiators
were placed at five locations. In Fig. 1, the green circles
represent the primary radiator. These radiators were placed
two beamwidths apart.

Fig. 3. Element design

The under and upper sides are the V- and H-polarized wave
elements, respectively. The elements are two-layered, with
V-polarized elements on the lower side of layer B and Hpolarized elements on the upper side. The parameters of theelements are listed in Table Ⅰ.

Fig. 1. Position of the primary radiator

TABLE I.

Fig. 2 shows the beam area where green circles indicate
the beams at the design frequency for each horn. For eachhorn, the beam must swing from the center frequency (f0) to
the high-frequency (fH) side and low-frequency (fL) side by
one beamwidth. As shown in the figure, fH of horn 1 and fLof horn 2 overlap to cover the service area efficiently. To
realize such a change in the beam direction according to thefrequency, a mirror surface should be designed. In theazimuthal direction, the area is covered by changing the beamdirection, depending on the polarization. In Fig. 2, the red andblue frames represent the V and H polarizations, respectively.
To change the beam direction depending on the polarization,
an element design must be performed, which requires two

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

13PARAMETERS OF THE DESIGNED ELEMENT

Thickness hA, hB

0.15λ0, 0.02λ0

Dielectric constant εr2.56, 2.59tanδ

0.0015, 0.0017

Line spacing SB

0.05λ0Line width w

0.02λ0Element length lA, lB

0.01~0.87λ0, 0.01~1.01λ0

Element spacing PX=PY

0.38λ02022 IEEE International Workshop on Electromagnetics: Applications and Student Innovation Competition (iWEM), Narashino,Japan

IV. REFLECTOR DESIGN

VI. MEASUREMENT RESULT

Fig. 4 shows the arrangement of the mirror surface, andTable II lists the design values. The elevation direction canchange the beam direction, depending on the frequency. To
achieve this, the horn angle of the image θ was determined. θ
can be obtained using Eq. (1) [7]. Based on the design value,
the horn angle of the image was 34.28°. Also, multiple
primary radiators should be placed to ensure that the beam
shift covers the area.

A contour map at 35 dBi is shown in Fig. 6. The
measurement results are shown in terms of directional gain.
The elevation confirms that the fL beam of horn 1 and the fH
beam of horn 2 overlap by a ±1 beamwidth from the f0 beam.
Similarly, the fL beam of horn 2 and fH beam of horn 3
overlap by ±1 beamwidth away from the f0 beam. TheAzimuths confirm that the V-polarized beam is emitted in thedirection of -0.67° and the H-polarized beam in the +0.76°direction. However, the directivity gain at the high-frequency
side (fH) of the H polarization was low for the five horns.

tantan1Fig. 4. The arrangement of the mirror surface
TABLE II.

Fig. 6. Contour map of 35 dBi

DESIGN PARAMETERS OF THE MIRROR SURFACEVII. CONCLUSION
Tilt angle θf [deg]42.14

Horn angle θd [deg]50Beam direction [deg]±0.65

Diameter of opening surface D

41.2λ0Distance from the primary radiator to the center ofaperture R

43.13λ0

Clearance c

12.43λ0

Frequency fL, fH

0.96λ0, 1.04λ0

The results of a study of reflectarrays with different beam
directions depending on the polarization and frequency arepresented. Based on the measurement results, the beamchanges in the elevation direction depending on the frequency,
and in the Azimuthal direction depending on the polarization.
In addition, the desired area can be efficiently covered using asingle reflectarray.
The gain reduction in the H polarization is believed to becaused by the element design. In the future, we plan to design
a device that does not degrade the gain.

V. ANALYS RESULTThis study was supported by JSPS(20K04491).

A contour map at 35 dBi is shown in Fig. 5. The analysis
was performed using the aperture distribution method. Thefigure confirms that the beam direction changes based on thefrequency and polarization to efficiently cover the desired
area [6].

REFERENCES
[1]
[2]

[3]

[4]

[5]

[6]

[7]
Fig. 5. Contour map of 35 dBi

14J. Huang and J. A Encinar, “Reflectarray antennas,” Wiley Online
Library, New Jersey, 2007.
S. Makino, R. Obata, K. Takeshima, Y. Sunaga, M. Takikawa, and H.
Nakajima, “Satellite Mounted Antennas Using Refrectarray Antenna,”
IEICE, 2018.
M. Fukaya, R. Obata, S. Makino, M. Takikawa, and H. Nakajima,“Reflectarray antenna changing beam direction by polarization,”
EuCAP, Denmark, March 2020．
R. Florencio, J. Encinar, R. R. Boix, V. Losada, and G. Toso,“Reflectarray Antennas for Dual Polarization and Broadband Telecom
Satellite Applications,” IEEE AP, vol.63, pp. 12341246, April 2015.
Y. Kaimori, S. Takino, S. Shigemitsu, and S. Makino, “Adaptation ofReflectarray Antenna to Yield Scanning-Spot Beam,” ISAP, October
2021.
Y. Kaimori, M. Takao, S. Makino, H. Nakajima, and Y. Nishioka,“Measurement Results of Scanning Spot Beam Reflectarray Antenna,”IEEE AP-S, July 2022.
S. Makino, “Estimation of Frequency Characteristics of Reflectarray
by Introducing Aberration Theory,” EuCAP, Paris, March 2018.