Page 103 - ITU Journal, Future and evolving technologies - Volume 1 (2020), Issue 1, Inaugural issue

ITU Journal on Future and Evolving Technologies, Volume 1 (2020), Issue 1

Fig. 4 – The effective permittivity and permeability of the unit cell.

Fig. 6 – Reflection phase distribution and 3D pattern of the coding meta-
surface with Horn antenna as an EM source located at (0 cm, 0 cm, 100
cm). (a) Ideal reflection phase distribution; (b) 3D pattern in full struc-
ture; (c) the beam pattern based on ideal phase distribution; (d) the
beam pattern contour for coding application.
beam. Fig. 6 (d) demonstrates contour plot with corre-
sponding 3D scattering pattern.
(a)

4.2 Beam-Steering Meta-surface Construction
In this section, an 8 × 8 beam steering meta-surface is
modeled and simulated using CST Studio software to ver-
ify the beam steering capability of the RIM. In this sim-
ulation, the meta-surface is in the X-Y plane, and a horn
serves as an EM source, which is located at (50 mm, 0 cm,
∘
∘
(b) 0 cm) with a rotation of (45 , 0 ) with respect to the meta-
surface. Then, an ON/OFF pattern matrix for steering to
Fig. 5 – (a) Horn antenna as a transmitter and (b) the 1-bit 10 × 10 ∘ ∘
meta-surface simulated model. (120 , 0 ) is loaded to the PIN diode of each unit cell. Fi-
nally, the simulation results are exported and shown in
Horn antenna is employed as a main radiator at the trans- Fig. 7 (a) and (b). It is clearly observed that the cod-
mitting side, as shown in Fig. 5 (a). The redesigned Horn ing meta-surface is capable of steering the beam to the
antenna is given to excite the meta-surface structure at desired direction with 20 angular resolution in the full
∘
5.3 GHz. In addition, the 1-bit 10 × 10 meta-surface simu- structure case.
lated model is shown in Fig. 5 (b).

5. EVALUATION IN VEHICULAR APPLICA-
4.1 Coding Meta-surface Construction TIONS

In this section we consider coding meta-surface based on The proposed RIM structure is now exploited for vehic-
the RIM structure, as the possibility to characterize the ular communications, as depicted in Fig. 1. Specifically,
states ON and OFF as matching the bits 0 and 1. Fig. 6 we consider the communication link in a vehicular con-
(a) shows a random coding meta-surface with a fixed ra- text, established from a source (red vehicle) and a receiver
tio and a different coding sequence, and Fig. 6 (b) shows node (green vehicle). We assume a highway scenario and
the simulated 3D radiation in full structure using CST. As the transmitter and receiver vehicles have constant speed
shown clearly, with coding sequence, the diffusion of the for the transmission time window. In order to character-
far-field pattern and the scattering amplitude at the nor- ize the impact of the controllable meta-surface in the com-
mal incident angle are apparently the same. According to munication system, we assume a simplified system with
the code MATLAB, a 3D far-field pattern can be obtained no interferences caused by others vehicles. In order to
with fixed ratio between 0 and 1 coding elements. The quantify the impact of the RIM on the performance sys-
simulated results are demonstrated as Fig. 6 (c). Once ra- tem, we will consider (i) the relation between different
tio fixed, the scattering amplitude at the normal incident beam width on the average rate, given a certain estimated
∘
angle 0 is determined, and the efficient of coding meta- velocity, and (ii) the derivation of the outage probability
surface only depends on the uniformity of the scattering and the analysis of the communication system in terms of

© International Telecommunication Union, 2020 83