One Layer of Reﬂectarray Antenna
Changing Beam Direction by Polarization
Shota Takino∗ , Shigeru Makino∗ , Sanshiro Shigemitsu∗ , Yusuke Kaimori∗∗ Kanazawa Institute of Technology 7-1 Ogigaoka, Nonoichi, Ishikawa, 921-8501 Japanemail : b1613265@planet.kanazawa-it.ac.jp

Abstract—Reﬂectarray antenna applies the reﬂection phase
control function of a metal loaded frequency selective reﬂector
to a reﬂector antenna, It is possible to control the reﬂection
phases of vertical (V) and horizontal (H) polarization with asingle reﬂectarray if the shape and arrangement of the elements
are appropriately designed In this study, we investigate a highprecision reﬂectarray using three linear elements in a single-layer
structure. The results of the analysis demonstrate that the mutual
coupling between the H and V components is reduced, and theeffect of manufacturing error is minimized. Consequently, it isinferred that the beam can be emitted in different directions foreach polarization.
Index Terms—frequency selective reﬂector(FSR), single layer,polarization, efﬁciency

I. I NTRODUCTION
A reﬂectarray[1] antenna applies the reﬂection phase control
function of a metal loaded frequency selective reﬂector to thereﬂector antenna. A plane wave can be formed by controlling the phase of the reﬂected spherical wave radiated fromthe primary source by appropriately selecting the shape anddimensions of the reﬂecting element. In addition to shaped
beams, the application of multiple beams to cover a service
area has been studied.
In particular, for multi-beam application, a coverage area
equivalent to that of conventional beams is realized by combining the coverage area in the elevation direction using thedependence of the beam shift on frequency and the cover in
the azimuth direction using the change in the beam direction
due to polarization. Based on these characteristics, a multiscanning beam method has been proposed [2],[3].
In this paper, we report on an element that changes the beam
direction depending on the polarization in one layer.
II. E LEMENT DESIGN
A. Design Model
Fig.1 shows the design model. In this study, we examined
the Ku-band reﬂectarray. The variation of the beam direction
by polarization depends on the resonant element. Therefore,
the element requirements are as follows:(1) Covers a 360◦ reﬂection phase region for each polarization.
(2) Independent phase control such that the two polarizations
do not affect each other’s reﬂection phase.
We examined the conditions that satisfy these two criteria.

The element design parameters are listed in Table I. This
device has an A layer on the ground plane, and the resonant
elements of each polarization are printed on the A layer in sucha manner that each polarization does not interfere with eachother, thus realizing independent phase control. The thicknessof the A layer was set to hA =0.1274λ0 to achieve a singlelayer.
We achieved a 360◦ reﬂection phase region cover for boththe polarized waves by using three line elements. The threeline elements extended ℓA1 and ℓB1 to 0.3944 λ0 , withℓA2 =0.3266λ0 . In addition, by changing the length of ℓB2 to0.3266λ0 , we achieved phase control with a gradual phasechange and an element that is resistant to manufacturing
errors. Here, the total element lengths are ℓA and ℓB , andℓA = ℓA1 + 2ℓA2 and ℓB = ℓB1 + 2ℓB2 are deﬁned.

Fig. 1. Phasing element

TABLE IE LEMENT DESIGN PARAMETERS
Thickness hA
Dielectric constant ϵrtanδLine width w
Element lengthℓA ,ℓB
Element spacingPX = PY

0.1274λ02.59
0.00280.004λ00.004-1.048λ00.41λ0

When designing the elements in a single layer, the vertical(V)polarized elements were placed with the horizontal(H)polarized elements moved 1/2PX in the x-axis direction and
1/2PY in the y-axis direction. The spacing between the threelines was set to SA1 =SB1 =0.0349λ0 .

B. Design Results
In this study, the element length of the V polarization
was ﬁrst ﬁxed at ℓA =1.048λ0 and the element length of theH polarization ℓB was varied between 0.004 and 1.048λ0 .
The element length of the H polarization was then ﬁxed atℓB =1.048λ0 and the element length of the V polarization ℓA
was varied between 0.004 and 1.048λ0 . The results of theanalysis are depicted in Fig.2. It was conﬁrmed that bothpolarizations covered a phase region of 360◦ or more. A
phase shift of approximately 20.83◦ was observed for the Hpolarization when the element length of the V polarization
was changed, and the phase shift of approximately 19.05◦
was observed for the V polarization when the element lengthof the H polarization was changed. Based on these results,
it can be inferred that the interference between the elements
is small, and independent phase control is possible for eachpolarization.

we can successfully swing the beam in the desired beam
direction and improve the aperture efﬁciency by approximately
20%.

Fig. 3. Radiation pattern of V-pol and H-pol

TABLE IIIB EAM DIRECTION AND GAIN ANALYSIS RESULTS
Fre.
f0Pol.
VH

Beam direction[deg]-1.518+1.523Gain[dB]
33.82
33.89

Efﬁciency[%]
6263

IV. C ONCLUSION
Fig. 2. Reﬂection phase characteristics of V-pol and H-pol

III. A NALYSIS R ESULT
A. Reﬂector design
The design parameters of the reﬂectarray are listed in Table
II. Here, the position of the primary radiator is F , and thecenter of the mirror surface is O.The beam directions aredesigned to be separated from each other by one beam width(=3.04◦ ).
TABLE IIR EFLECTARRAY DESIGN PARAMETERS
Tilt angle[deg]Beam direction [deg]Diameter of opening surface D
Distance from F to O R
Clearance c

25±1.52
20.33λ018.29λ03.85λ0A full wave analysis was performed on the designed reﬂectarray using the LinkedField function of HFSS (by ANSYS). Fig.
3 shows a comparison between the calculated values of theradiation patterns for H polarization and V polarization at thecenter frequency of f0 . The beam shape was maintained at thecenter frequency. Table III lists the beam direction, gain, andaperture efﬁciency for each polarization. Based on the results,

In this study, we attempted to improve the aperture efﬁciency by changing the structure from two layers to one
layer using three wire elements. Consequently, the aperture
efﬁciency was successfully improved by approximately 20%
during the analysis, and the beam direction was almost thesame as the desired beam direction. In the future, we plan toevaluate the performance of the newly designed single-layer
reﬂectarray antenna through actual prototyping and measurement.
R EFERENCES[1] J.Huang et al.,Wiley,New Jersey,2007.
[2] M.Fukaya et al., 2017 ISAP.
[3] S.Makino et al.,IEICE,B-1-51,2018.