A Band Notched Ultrawideband Antenna Prajakta Umbarkar 1 , Prof. R.P.Labade 2 Amrutvahini College Of Engineering , Sangamner – 422605 . Email id : prajaktaumbarkar@gmail.com 1 , rplabade@gmail.com 2 . Abstract : This paper presents the design of Microstrip line feed rectangular-cut ultra wideband (UWB) antenna with notched- band characteristic. The antenna has been designed on a FR4 substrate with dielectric constant ℇr = 4.4, loss tangent (tan δ) =0.002 The antenna has been optimized to exhibit UWB characteristics from frequency range 3.1GHz–12 GHz except the notched-band frequency 5.2 GHz to 5.8 GHz. The radiation pattern of this antenna is nearly omni-directional in H-plane and bidirectional in E-plane. The effect of various design parameters on notched characteristics have also been analyzed using CAD Feko 6.1 simulator using MoM[14]. The simulated results are in good agreement with FCC standards showing VSWR <2 throughout the band 3.1GHz to 12GHz, except the notched-band. This antenna can be easily integrated with microwave circuitry and useful for UWB applications. Keywords:Microstrip antenna, Monopole antenna, Band- notched, Microstrip line-feed and UWB system, Stepped Impedance Resonators. I. INTRODUCTION : In 2002, Federal Communication Commission (FCC) authorized unlicensed use of UWB band ranging from 3.1GHz to 10.6 GHz. UWB system plays a crucial role in communication system as the antenna is one of thewireless communications components. The UWB antenna is a specific component whosetransmitting andreceiving properties differ from those for conventional narrowband operation. There lies different wirelesscommunication systems which overlap the UWB band. To avoid interference due to these frequencies, UWBantenna must be able to reject such frequencies with very fine rejection characteristics. For this purpose,numerous notches are created at particularfrequency band which have rejection characteristic over a limitedbandwidth. A number of antennas with band-notched property have been discussed and various methods havebeenused to achieve the function. UWB antenna can beachieved byuse of simple microstrip line and properdesigning of ground structure [1]. While widely used methods for notched-band are created slots on the patch oron the ground plane, i.e., straight, triangular, E-shaped, H-shaped, U-shaped, and folded strip-line slots [2-5].The all these notches techniques are very expensive way to obtain notched characteristics in an expected bandof frequency [6]. The notched bands can be generated by a band notched filter composed of double steppedimpedance resonators (SIRs) [7-8]. Split ring resonator is one of the widely used and appreciated structure usedfor creating notches at particular frequencies [10-11]. Adding parasitic element is another advantageous methodto generate notched band [9]. Square ring resonator and a square parasitic element can be used to have notchedcharacteristics in UWB antenna [12-13]. The notched-band characteristic achieved by parasitic elements so farreported by having parasitic element on the back of substrate or adjacent to patch. This requires the double sideprinting or increase the overall size of antenna. In this paper, parasitic element to create notched-band isproposed, which does not require double side printing and also not increase the size. II. ANTENNA DESIGN: Fig. 1 And 2 shows the geometry of a UWB monopole antenna. The antenna is fabricated on FR4 substrate with dielectric constant of 4.4 and thickness of 1.6 mm. The radiating element and feeding line are printed International Journal of Scientific & Engineering Research, Volume 4, Issue 5, May-2013 ISSN 2229-5518 IJSER © 2013 http://www.ijser.org 1664 IJSER