Adaptation of Reflectarray Antenna
to Yield Scanning-Spot Beam
Yusuke Kaimori1*, Shigeru Makino1, Shota Takino1, Sanshiro Shigemitu1
1

Kanazawa Institute of Technology 7-1 Ogigaoka, Nonoichi-shi, Ishikawa, 921-8501, Japan*email: b1714005@planet.kanazawa-it.ac.jp

Abstract—Herein, a novel reflectarray antenna design with amirror configuration is proposed. Through adaptation of thereflectarray antenna's frequency and polarization (two of its
characteristics that change beam direction), a multi-scanningbeam can be realized, whose performance matches that of aconventional multi-spot beam with one reflecting mirror. A
scanning-spot beam that changes beam direction using frequency
in the elevation direction and polarization in the azimuth directionin the Ka band is examined. As a result, it is verified that the
proposed design efficiently covers the desired service area.

between the elements is small, and independent phase control
is possible for each polarization.

Keywords—reflectarray, mirror configuration, scanning spot
beam

I. INTRODUCTION
As per prior research, in a multi-beam communication
system using reflectarray antennas, a service area can be covered
using a few mirror planes by changing the beam direction withrespect to its polarization and frequency [1]-[4]. In this paper, anew reflectarray design is proposed that changes the beamdirection using a mirror configuration and a linear element.

Fig. 1. Element shape

TABLE I ELEMENT DESIGN PARAMETERSA

II. ELEMENT DESIGN
A. Design modelFig. 1 shows the linear element employed to change phaseaccording to the reflectarray polarization [5]. Table Ⅰ lists theelement parameters. For gradual phase control, the lengths ofthe three linear elements are extended as follows: lA1 and lB1 to0.36λ0, lA2 to 0.215λ0, and lB2 to 0.24λ0. Here, the total element
lengths of layer A and layer B are lA and lB, respectively, andthey are defined as lA = lA1 + lA2 and lB = lB1 + lB2.
B. Design results
The H-polarization element length was fixed at lB = 0.84λ0,
and that for V-polarization, lA, was varied from 0.01λ0 to 0.79λ0.
Similarly, the V-polarization element length was fixed at lA =0.79λ0, and that for H-polarization, lB, was varied from 0.01λ0
to 0.84λ0. Fig. 2 and 3 show the respective analysis results. Bothpolarizations could cover a phase region of 360° or more.
Moreover, a phase change of approximately 0.75 ° wasobserved when the element length of the V polarization wasvaried, and a phase change of approximately 1.19 ° wasobserved when the element length of the H polarization wasvaried. Therefore, it can be inferred that the interference

Fig. 2. Reflection phase characteristics of V-polIV. ANALYSIS RESULT

Fig. 3. Reflection phase characteristics of H-polAs per the design parameters, analysis was performed via theaperture distribution method. The resonant element used in thedesign was assumed to be an ideal element with no frequency
characteristics. Fig. 5 shows the 35 dBi contour map for threefrequencies and two polarizations at each of the five horns.
Clearly, the V-polarized beam was emitted in the azimuth
direction at –0.65 degrees, and the H-polarized beam emitted at+0.65 degrees in the elevation plane. The fH beam of horn 1 andfL beam of horn 2 overlap ±1 beam width away from the f0 beam.
Similarly, the fL beam of horn 2 and the fH beam of horn 3
overlap ±1 beam width away from the f0 beam. Thus, a single
reflectarray can efficiently cover the desired service area.

III. REFLECTOR DRSIGN
Fig. 4 shows the mirror configuration, and Table Ⅱ list themirror surface design specifications. The five primary radiators
were placed in a way that beams of frequencies fL and fH are
located 1 beam width away from the beam at the center
frequency f0. Radiators 1 and 3 were located +2 beam widths
and -2 beam widths away from the center respectively, in theelevation direction while radiator 2 was located at the center
Radiator 4 was +0.87 and +0.5 beam widths away from thecenter in the azimuth and elevation directions, respectively,
whereas radiator 5 was +0.87 and -0.5 beam widths away fromthe center in the azimuth and elevation directions, respectively.

Fig. 5. 35dBi contour map

V. CONCLUSION
The results show that the beam direction varies dependingon the polarization and frequency of the reflectarray, which was
the aim of this study. In the future, we plan to fabricate areflectarry based on the design parameters proposed in this study
and further examine the validity of the design.
This study was supported by JSPS(20K04491).
Fig. 4. Mirror configuration

REFERENCES[1]

TABLE II MIRROR SURFACE DESIGN PARAMETERS

[2]

[3]

[4]

[5]

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