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This paper is dedicated to different experimental validations concerning a novel concept of beam forming and beam steering antenna. The working principle of the antenna is based on the equivalent radiating surface approach and inspired from an electromagnetic band gap antenna. The theoretical aspect and some numerical validations have been already published in the work of Abou Taam et al. (2014). Different electromagnetic behaviors have been demonstrated, such as low mutual coupling, and high gain preservation for high scanning angles values. In this paper, some of these electromagnetic behaviors will be proven experimentally by the means of two different feeding configurations.

Current radiating systems still rely on array approach, for example, the patch, the dipole, and the waveguide slots array [

The proposed approach working principle constitutes the subject of an accepted CNRS (Centre National de la Recherche Scientifique) patent [

To recall, the radiating system is called “Agile Radiating Electromagnetic Band Gap Matrix Antenna.” The matrix consists of a 1D, 2D, or conformal arrangement of several identical and jointed pixels. Each pixel is inspired from an electromagnetic band gap (EBG) antenna and presents a special radiating aperture which is square with uniform electric field distribution. The whole radiating surface (characterized by electric (

In this paper, two experimental configurations, that is, beam forming network (BFN) + matrix antenna, will be described in order to prove the theoretical aspect, as in [

The first step in designing the matrix antenna is the modeling of the EBG pixel. Figure ^{2}) directly printed at the bottom of the FSS dielectric substrate (

Elementary pixel: (a) perspective view and (b) inside view (cut-plane at the middle along (

(a) FSS dimensions. (b) Detailed dimensions heights of the pixel (inside view, cut-plane at the middle along (

After completing the optimization and the design of the EBG pixel, the next step is to form a 1D matrix antenna which consists of 17 jointed pixels spaced by ^{3}). The total height of the matrix antenna (6 mm) corresponds to the cavity (1 mm), the ground plane (1.9 mm), and the substrates heights (3.1 mm), as shown in Figure

The designed prototype of 1D matrix antenna formed by 17 jointed pixels linearly spaced by

Figure ^{3}). On the bottom of the metallic support, a BFN is installed in order to feed the pixels of the matrix antenna. More details on the BFN will be presented in Sections

Matrix antenna manufactured prototype placed at the top of a metallic support.

The next section focuses on the experimental validation of the matrix antenna leading to prove the robustness of the theoretical concept and the efficiency in beam forming and beam steering.

The matrix antenna concept was validated through a numerical simulation, as described in [

Simulated and measured matching coefficients corresponding to central and border pixels.

Moreover, as mentioned in [

Simulated and measured coupling coefficients from the central pixel to first left neighboring one (

Next in Sections

In spite of all the undesirable radiation effects of the Gaussian beam, it is still the most common and used beam radiation type in antenna systems. This type of beam leads to a maximum gain compared to a different form of beams, that is, sectorial beam. In this paragraph, an experimental validation using a passive BFN composed of commercial equimodulus and equiphase power divider (

Beam forming network placed at the metallic support’s bottom leading to obtain a Gaussian radiation beam.

A full-wave simulation of the matrix antenna is performed with CST Microwave Studio. The matrix was associated with the measured passive BFN (touchstone file) using a cosimulation technique on CST and the whole system (measured BFN + simulated antenna) was simulated in order to compare correctly the measured and the simulated radiation patterns.

Two cases of figures are considered: the broadside direction and the steered direction at 30° pointing angle. First of all, the simulated and measured matching coefficients of the global system are shown. The results show a good agreement in both cases (0° and 30°) and the system is matched (Figure

Simulated and measured matching coefficients of the global system for the first configuration: (a) broadside direction and (b) 30° pointing angle.

Then, Figures

Comparison between simulated and measured normalized Gaussian beams at (a) broadside direction and (b) 30° pointing angle.

One cannot ignore the undesirable radiation effects of the Gaussian beam, for example, high side lobe levels, back radiation, and particularly 3 dB gain variation in the aperture. However, there are a lot of techniques which permit us to avoid these undesirable effects and even overcome them. The proposed methodology, in this paper, is to generate a special sectorial beam radiation in order to confine the electromagnetic energy between two angles. Such beam presents a quasiconstant gain over a desired angular range, as illustrated in Figure

Illustration of the Gaussian beam radiation (a) and the proposed sectorial beam radiation (b) steered at

Illustration of (a) Gaussian beams and (b) sectorial beams for beam steering scenario.

To recall, the radiation patterns, according to equivalent radiating surface theory, are obtained approximately by a spatial Fourier transform (FT) of the near field distribution existing on the antenna’s radiating surface. For example, equimodulus and equiphase excitation law enables us to obtain a Gaussian beam which has almost the shape of a cardinal sine. Contrariwise, the proposed idea is to obtain a sectorial radiation pattern from a cardinal sine excitation. To carry out, the proposed idea consists of feeding the pixels of the matrix antenna by a cardinal sine excitation law. The cardinal sine signal is sampled by the pixel number. Therefore, each pixel is fed by special weight in modulus and in phase. In order to achieve that, a nonequimodulus and nonequiphase distribution circuit 1 input to 17 outputs, which is able to generate the cardinal sine excitation law, has been designed (Figure

Cardinal sine power divider: (a) momentum layout and (b) manufactured prototype.

In order to experimentally validate the sectorial beam radiation, another configuration was realized, based on the first configuration presented in Figure

The simulated and the measured matching coefficients on the central input for two cases (0° and 30°) are shown in Figure

Simulated and measured matching coefficients of the global system for the second configuration: (a) broadside direction and (b) 30° pointing angle.

Comparison between simulated and measured normalized sectorial radiation patterns at broadside direction: (a) 8 GHz, (b) 8.2 GHz, and (c) 8.4 GHz.

Comparison between simulated and measured normalized sectorial radiation patterns at 30° pointing angle direction: (a) 8 GHz, (b) 8.2 GHz, and (c) 8.4 GHz.

This paper was dedicated to demonstrate experimentally the beam forming and beam steering capabilities of an innovative antenna called “Agile Radiating Electromagnetic Band Gap Matrix Antenna.” The antenna theoretical concept was already published in [

Many short- and long-term perspectives are being investigated. The most recent one is the reduction of the grating lobes effect which was already demonstrated theoretically in [

Finally, the matrix antenna provides a robust, reliable, and efficient solution to new design capabilities for agile antenna applications where the beam forming and beam steering are sought criteria.

The authors declare that there is no conflict of interests regarding the publication of this paper.