A Compact Printed UWB Antenna Having Slots with Reconfigurable Band Notched Characteristics

Abstract

In this thesis, a compact and simple planar microstrip line fed Ultra-Wide Band Antenna (UWB) with reconfigurable dual band notch capability is discussed. The circular microstrip patch antenna on the front plane with partial ground at the bottom plane is used in order to attain the UWB characteristics. Despite, Federal Communications Commission’s (FCC) allocation of UWB as unlicensed band for the commercially available applications, UWB band is also acquired by few other narrow band commercial services like WiMAX (3.30 GHz to 3.69 GHz) and WLAN (5.150 GHz to 5.85 GHz). It is therefore preferable to come up with a UWB antenna with notching capabilities to alleviate the probable electromagnetic interference of the UWB with the coexisting narrow band systems over the entre UWB frequency band. In our design, the unwanted intrusion due to the overlap of UWB with such communication systems is overcome by using two notch filters. We optimized the slot dimensions, hence notching the two bands efficiently and place them appropriately in the radiating circular patch. Numerous UWB antennas and other band notched UWB antennas with great attributes have been proclaimed earlier, but the notched bands were not reconfigurable. While in our design, in addition to notching, reconfigurability is also introduced to switch the notched bands. Two copper strips have been incorporated in the slots at the optimized locations making the notched bands reconfigurable. The On and Off conditions of notched bands could be controlled by switching the diode and there are then four possible combinations based on the states of two switches. The antenna exhibits nice performance along with an adaptable double band rejection capability. The impedance bandwidth for 10 dB return loss is 2.92 GHz – 11 GHz with VSWR < 2 dB except at notched bands. The antenna is designed and simulated on HFSS using Rogers Duroid 5880 which has dielectric constant 2.2 whereas loss tangent 0.02 with dimensions 30 x 35 mm sq. It has promising radiation characteristics and acceptable gain. Simulated results illustrate that the antenna could be considered for UWB applications.