UWB and Reconfigurable Antennas for Cognitive Radio Application using MEMS Technology

A survey on ultrawide band and reconfigurable microstrip patch antennas for cognitive radio application is discussed in this paper. Cognitive radio is an intelligent wireless communication system that is aware of its surrounding environment(i.e., outside world), and uses the methodology of understanding-by-building to learn from the environment and adapt its internal states to statistical variations in the incoming RF stimuli by making corresponding changes in certain operating parameters (e.g. transmit-power, carrier-frequency, and modulation strategy) in real-time. For the realization of a CR system, wideband and narrow band antennas are required. A UWB antenna is considered for the wide band operation and they are those systems which cover a large spectrum in the range of 3.1GHz to 10.6GHz and are used for sensing vacant slots in the spectrum. Reconfigurable antennas usually frequencies reconfigurable are considered as narrow band antenna which is used for transmission of data through the vacant slots sensed by the wide band antenna. MEMS technology provides efficient path to achieve ultra wide band antenna coverage and can be used in faster wireless communication applications.