Frequency selective reconfigurable microstrip antenna for cognitive radio applications

For the efficient utilization of electromagnetic radio spectrum cognitive radio communication system is employed, which deals with the spectrum scarcity. An efficient antenna is essential for the appropriate selection of the available frequencies. This paper presents the design and implementation of frequency reconfigurable antenna for cognitive radio applications. Reconfigurable inverted U-shape microstrip patch antenna feeding by 50 W microstrip line is designed and implemented. The designed and implemented antenna applied for switching frequency between 3.25 GHz to 4.1 GHz by choosing a specific sub-band from the specified wideband.  The frequency reconfiguration was achieved by using twelve PIN diode switches by placing them on the slotted ground plane of the antenna. The PIN diodes were organized in such a way as to alter antenna bandwidth and to shift the operating band. The switching of PIN diodes controlled using the microcontroller to select the appropriate frequency. The performance of the simulated and fabricated antenna is investigated using different parameters.