A Study of beam reconfigurable antenna systems for small cell base station

Abstract

In a mobile and wireless system, a base station (BS) transmits and receives signals from a multitude of cellular phones or mobile terminal (MT) units. Generally in the past, the simplest BS architecture is the omni-directional BS, which transmits and receives RF signals in all directions. So, it is a waste of resources and generates too much interference between information systems. Nowadays, we can increase BS capacity by using directional antennas to partition the cell into multiple sectors. The directional antennas or a similar antenna can be known as smart antenna. Switched beam and adaptive array systems are one of smart antenna category, which enable a base station to customize the beams they generate for each remote user effectively by means of internal feedback control. Smart antennas (also known as adaptive array antennas, multiple antennas and recently MIMO) are antenna arrays with smart signal processing algorithms used to identify spatial signal signature such as the direction of arrival (DOA) of the signal, and use it to calculate beam forming vectors, to track and locate the antenna beam on the mobile/target. The antenna could optionally be controlled the beam in several schemes to direct to the desire of arrival signal to maximize performance metric (e.g., SNR, signal energy and channel capacity). This dissertation deals with the development of new trend smart antennas for next-generation wireless communications base stations. Reconfigurable and switched four port antenna arrays for smart antenna applications have been designed and inspected. The integration of antenna elements, feed and bias switching network is considered, build with optimal and compact size that appropriate for array configuration in order to have a reconfigurable beam pattern. Novel cubic antenna array configuration has been reported in this work also. The cubic array is composed of four reformed modified monopoles which are orthogonal to each other. Good agreement between ...