Abstrakt

Smart Antennas for Communications in Line of Sight

Surayamubeen, A.M.Prasad, A.Jhansi Rani

Throughout the world, including the United States, there is significant research and development on smart antennas for wireless systems. This is because smart antennas have tremendous potential to enhance the performance of future generation wireless systems as evidenced by the antennas? recent deployment in many systems. It covers smart antenna technology, including software and system aspects. First the two basic types of smart antennas, adaptive and phased arrays are described and then their current use and proposed use in future wireless systems is discussed. A smart antenna is therefore a phased or adaptive array that adjusts to the environment. That is, for the adaptive array, the beam pattern changes as the desired user and the interference move; and for the phased array the beam is steered or different beams are selected as the desired user moves. We describe and analyze adaptive antenna array technology to improve naval communications systems to beyond line-of-sight at microwave frequencies by using the ducting layer as a leaky waveguide and the adaptive array to resolve and coherently combine multipath in this layer.