Design of ultra-wideband antennas with signal rejection characteristics for biomedical applications.

摘要

The allocation of the 3.1-10.6 GHz spectrum by the Federal Communications Commission (FCC) for Ultra Wideband (UWB) radio applications has presented many exciting opportunities and challenges for the researchers in academia and industry for the exploitation of several novel antenna design suitable for UWB communication. The successful transmission and reception of short pulses used for UWB communication that occupies the entire 3.1-10.6 GHz spectrum require an antenna with characteristics like linear phase, low dispersion and VSWR ≤ 2 throughout the entire band. Linear phase and low dispersion are marked by low values of group delay and is imperative for transmitting and receiving a pulse for distortion free communication. VSWR ≤ 2 is required for proper impedance matching throughout the UWB band which ensures at least 90% of total power radiation is achieved by the designed antenna. On the other hand, there are other narrowband system that operates at 5.15-5.85 GHz are occupied by Wireless Local Area Network (WLAN), which causes electromagnetic interference to the UWB systems. To avoid this interference, a band- notch filter is required which is achieved by adding slots in the radiating patch or the ground plane. This helps to remove the necessity of using band rejection filter with the UWB antenna for rejecting the interfering frequency band.;By adding slots either in the radiating patch or ground plane of the UWB we can eliminate the interference of the operating frequency band of WLAN systems. The focus of this research is to develop miniaturized novel antennas for the UWB 3.1-10.6 GHz band with signal rejection characteristics which has WLAN (5.15-5.85 GHz) band rejection and achieves a physically compact, planar profile, sufficient impedance bandwidth, high radiation efficiency and nearly Omni-directional radiation pattern well suited biomedical applications like medical monitoring, medical sensor data collection and medical imaging systems.