Frequency Reconfigurable Microstrip Antenna for Cognitive Radio Applications

Abstract

This paper presents a selective frequency reconfigurable antenna, suitable for cognitive radio applications. Reconfigurability is achieved by inserting PIN diode switches in DMS(defected microstrip structure) ‘T’ slot filter. The proposed antenna is capable of switching between a wide operating band of 3.0 GHz – 10 GHz and six different narrow band operating from 5 GHz to 10 GHz. UWB case is used for sensing the entire band and then adjusting its bandwidth to select the suitable sub-band and pre-filter out the other ones to communicate with wireless devices without interference with others. The proposed antenna patch is a combination of two semi-circular patches. For each case reflection coefficient is calculated, it maintains less than -10 dB throughout the operating frequency. Radiation Patterns for each case also reveal a very low distortion as required. Gain is more than 70% in each case.