<p>In this paper, a single neuron neural network beamformer is proposed. A perceptron model is designed to optimize the complex weights of a dipole array antenna to steer the beam to desired directions. The objective is to reduce the complexity by using a single neuron neural network and utilize it for adaptive beamforming in array antennas. The selection of nonlinear activation function plays the pivotal role in optimization depends on whether the weights are real or complex. We have appropriately proposed two types of activation functions for respective real and complex weight values.   The optimized radiation patterns obtained from the single neuron neural network are compared with the respective optimized radiation patterns from the traditional Least Mean Square (LMS) method. Matlab is used to optimize the weights in neural network and LMS method as well as display the radiation patterns.</p>

Purpose -As commercial and military aircraft continue to be subject to direct lightning flashes, there is a great need to characterize correctly the electrical currents and electric potential fluctuations on an aircraft to determine alternative design approaches to minimizing the severity of the lightning-aircraft dynamics. Moreover, with the increased severity of thunderstorms due to global warming, the need arises even more to predict and quantify electrical characteristics of the lightning-aircraft electrodynamics, which is normally not measurable, using a reliable electric model of the aircraft. Such a model is advanced here. The paper aims to discuss these issues. Design/methodology/approach -The case considered in this paper is that of an aircraft directly attached to an earth flash lightning channel. The paper develops a new approach to modelling the aircraft using electric dipoles. The model has the power to represent sharp edges such as wings, tail ends and radome for any aircraft with different dimensions by using a number of different sized dipoles. The distributed transmission line model (TLM) of the lightning return stroke incorporating the distributed aircraft model is used to determine aircraft electrical elements and finally the electric current induced on the aircraft body due to lightning's interaction with the aircraft. The model is validated by the waveform method and experimental results. Findings -The dipole model proposed is a very powerful tool for minute representation of the different shapes of aircraft frame and to determine the best geometrical shape and fuselage material to reduce electric stress. This charge simulation method costs less computer storage and faster computing time. Originality/value -The paper for the first time presents a computer-based simulation tool that allows scientists and engineers to study the dynamics of voltage and current along the aircraft surface when the aircraft is attached to a cloud to ground lightning channel.

Abstract-Multipath reflections are prevalent in underground mine wireless communication systems and are less constructive when an omnidirectional antenna is used. This phenomenon can be significantly controlled by eliminating the source of all multipaths with a single beam. The single beam must be rotatable towards the desired user to be of any use. The single directed beam will avoid generating multipath reflections and efficiently consume the valuable stored energy. In this paper we present an analysis of an array antenna using dipoles that forms a single beam without the need for reflectors or any complex arrangement of the array elements. It can be shown that dipole elements placed in a straight line are not effective in minimizing energy consumption and a minimum of three elements are sufficient for forming a single directed beam that is electronically rotatable to all directions. We have compared three, four and six elements for the accuracy. It is also shown that the elements of the array antenna should b placed on the circumference of a circle to avoid re-computation of weights to rotate the beam on to any desired direction, thus significantly reducing the computational burden of the single beam, steerable smart antenna.

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This paper reviews the use of Artificial Neural Networks in lightning related problems, and especially in locating the lightning using a signal sensor with a three element antenna and signal processor. A model to correctly represent both lighting return stroke currents and the radiated lightning electromagnetic pulses (LEMP) is presented with carefully chosen damping coefficients, or frequencies, following a previous work on this. The designed lighting return stroke model is shown to clearly demonstrate the distinct patterns of the LEMP at different distances. This model is used as a test bed to demonstrate the intelligent tracking three element antenna (using inverse computation signal processor) that may be used with a neural network classifier to locate the distance of lightning strike from the three element antenna sensor.