Design and Implementation of Ultra Wideband Antenna with Multiple Notched Bands

Abstract

The Federal Communications Commission (FCC) assigned 7.5GHz (3.1-10.6) ultra wideband (UWB) for unlicensed use in February 2002. Characteristics such as wide impedance bandwidth and low power emission limit of -41.3dBm/MHz has generated countless opportunities to design a high data rate UWB communication system. However, over the designed bandwidth of UWB system, there exist narrow band services for other communication systems, such as 3.4-3.69GHz for WiMAX, 5.15-5.35GHz and 5.725-5.825GHz for WLAN, 7.25-7.75GHz for downlink of X-band satellite communication and 8.02-8.4GHz for satellite communication band (ITU) system, which creates interference with the UWB system. Therefore, it is necessary for UWB antenna to perform notched band function in these frequency bands to avoid these interferences. A novel compact UWB planar antenna is developed from the conventional rectangular monopole antenna. To improve the impedance bandwidth, three bevel slots on the lower portion of the radiator patch and a single bevel slot on the ground plane of the conventional antenna are etched. The antenna so obtained, has a stable radiation pattern over a whole UWB bandwidth. A compact ultra wideband (UWB) antenna with dual notch band characteristic has been proposed. The antenna has two U- shaped slots on the radiating patch. The proposed antenna can reduce the interference of UWB with WiMAX and WLAN. The proposed antenna has a small size of 26×27mm2 and achieved an operating bandwidth (VSWR<2) from 2.6GHz to 10.8GHz, with one frequency notched band at 3-3.9GHz (WiMAX) and other at 5-5.9GHz (WLAN). A microstrip feed ultra wideband (UWB) antenna with triple notch band characteristic has been proposed. Three U-shaped structures are etched on the radiating patch. The proposed antenna reduces the interference of UWB with WiMAX, WLAN and ITU. The proposed antenna achieved an operating bandwidth (S11<-10dB) from 2.68GHz to 12GHz, except at notch band 3-3.85GHz , 5-5.9GHz and 8-8.8GHz. A novel small CPW feed UWB antenna with five notch band characteristic has been presented to suppress the potential interferences in ultra wideband systems. This proposed antenna has a small dimension of 30×32×1.6mm3 over the operating bandwidth (S11<-10dB) from 2.8GHz to 11.6GHz. By introducing five U-shaped slots, five notches are achieved in WiMAX (3.1-4GHz), WLAN (5-5.4GHz and 5.7-5.9GHz), X-band downlink (7.2-7.75GHz), and ITU service band (8-8.4GHz). These proposed plannar monopole UWB antennas are simulated, fabricated and tested. Measured results shows a good agreement with simulated results. In addition, these presented antennas have stable gain and omnidirectional radiation patterns, which make them suitable for UWB wireless applications.