Measurement Results ofScanning Spot Beam Reflectarray Antenna
Yusuke Kaimori (1), Masayoshi Takao (1), Shigeru Makino (1), Hiromasa Nakajima (2), and Yasuhiro Nishioka (2)(1) Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi-shi, Ishikawa, Japan(b1714005@planet.kanazawa-it.ac.jp)(2) Mitsubishi Electric Corporation, 5-1-1 Ofuna, Kamakura-shi, Kanagawa, Japan
Abstract— Conventional multi-spot beams and multi-scanningbeams using a single reflector have been developed by combining
the characteristics of a reflectarray antenna to change the beam
direction according to the frequency and polarization. In previousstudies, we showed 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 paper, the measurement results of thescanning spot beam reflectarray antenna fabricated based on thedesigned values are presented.
Keywords—reflectarray; scanning spot beam; polarization;
frequency

I. INTRODUCTION

The opening diameter D was 41.2λ0. In Fig. 1, two CAD
drawings are depicted; however, they become a single mirror
surface because these are superposed on two layers. The image
on the left of Fig. 1 is the V-polarization mirror surface, printedon the back of dielectric layer B. The image on the right is amirror surface of the H-polarization, printed on the surface ofdielectric layer B.
III. ANALYS RESULTThe contour map at 35 dBi is shown in Fig. 2. The analysis
was performed using the aperture distribution method. It can beconfirmed that the beam direction changes with frequency andpolarization, efficiently covering the desired area (Fig. 2).

In a multi-beam communication system with reflectarray
antennas, a service area can be covered using a few mirror planes
by changing the beam direction according to the polarization andfrequency [1][2][3][4]. In this paper, we present themeasurement results of a reflectarray fabricated using the design
method discussed in a previous report [5].
II. REFLECTARRAY DESIGN
The mirror surface was fabricated using the design values
obtained in a previous study [5]. The computer-aided design(CAD) figure of the mirror surface of the reflectarray with therespective elements is shown in Fig. 1.

Fig. 2. 35dBi contour map

IV. MEASUREMENT RESULT

Fig. 1. CAD data of reflectarray

The measurement results are presented in terms of directivity
gain. The radiation characteristics of V-polarization in theelevation plane are shown in Fig. 3, and those of the Hpolarization are shown in Fig. 4. The beam directions atfrequencies fH and fL were radiated ±1 beam width away fromthe beam at the center frequency. However, the directivity gain
at a high frequency (fH) of the H-polarization was low, probablyowing to an element design problem.

Fig. 3. Radiation patterns of V-polarization (Elevation cut)

Fig. 6. 35dBi contour map

V. CONCLUSION
The results of a study on reflectarrays with different beam
directions, depending on the polarization and frequency, arepresented. The measurement results show that the beam changes
with frequency in the elevation direction and polarization in theazimuth direction. Thus, it is feasible to cover the desired area
efficiently with a single reflectarray.
Fig. 4. Radiation patterns of H-polarization (Elevation cut)

The radiation characteristics in the azimuth plane (f0) arepresented in Fig. 5. The V-polarized beam was emitted in the−0.67° direction, and the H-polarized beam was emitted in the+0.76° direction. The V-polarized beam were generally
consistent with the analytical results, but the H-polarized beamchanged by +0.11° compared with the analytical results.

In the future, we believe that the gain reduction in Hpolarization is attributed to the element design. We plan todesign a device that does not degrade the gain.
This study was supported by JSPS(20K04491).
REFERENCES[1]
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Fig. 5. Radiation pattern of f0 (Azimurth cut)

The contour map at 35 dBi is shown in Fig. 6. The desired area
was efficiently covered by a single reflectarray, as shown in theanalysis results. However, the directivity gain at the highfrequency side (fH) of the H-polarization was low for all fivehorns.

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