Neural Network Synthesis Beamforming Model For Adaptive Antenna Arrays FADLALLAH Najib 1 , RAMMAL Mohamad 2 , Kobeissi Majed 1 , VAUDON Patrick 1 IRCOM- Equipe Electromagnétisme 1 Limoges University 123, Avenue Albert Thomas – 87060 Limoges FRANCE 2 Lebanese University - Equipe Radiocom Saida – Liban Abstarct: - This work proposes a neural adaptive synthesis system combines feedforward (FF) artificial neural network (ANN) with a backpropagation (BP) learning algorithm and linear antenna arrays. The proposed neural network allows the beamforming synthesis of array antenna steered beam with low side level and the creation of null in prescripted direction of interfering signals by controlling the amplitude and the phase excitation of each element. Key-Words: - 1. Phased Array, 2. Beamforming, 3. Neural Network, 4. Synthesis Antenna, 5. Backpropagation, 6. Preprocessing and PostProcessing. 1. INTRODUCTION Adaptive antenna arrays require extensive modelling and simulations prior to their practical implementation [1]. In a smart antenna arrays system, the beam is positioned electronically by adjusting the phase between elements of an array in a predetermined manner. This operation of synthesis [2] for antenna arrays is essential in the conception of an optimised antenna. This way requires a faster and more accurate control of the radiation of antennas [3]. The required processing has the task of maximizing the gain in the direction of the user, and canceling undesired signals, like inter-user interference, multipath and jammers, which highly degrade the system performances that use the hypothesis of uncorrelated noise [4]. The Neural Networks shown [5, 6] can to be useful in the control of phased arrays for detection and signal location. In particular, neural networks can control arrays with various types of element and network failures and can still perform accurate signal location, despite the errors. Since a trained neural network has output nodes that correspond to input waves from specific angular directions. In this paper we explore the neural network model feasibility of realizing beams steering and reducing interfering signals in mobile communications. We use a phase and amplitude excitation control to create desired beam and we present typical examples to demonstrate the efficiency of the proposed method. 2. SYNTHESIS PROBLEM FORMULATION The synthesis of antenna arrays is defined as being the research of the relative parameters positions and the current of excitations (amplitudes and phases) of the sources constituting the array in order to approach the desired function of radiation as well as possible [7].