ABSTRACT
This chapter deals with the frequency-notching techniques of various Ultrawideband (UWB) antennas to minimize the interference of various narrowband radiations with the overlapping UWB radiation. UWB signals are suitable for underlay communications, over a frequency band with other active systems. Hence, coexistence of UWB and other systems is eminent, however, with minimal mutual interference impacting their respective performance. RF spectrum spans from ultra-low frequencies (a few kilohertz) up to submillimeter waves corresponding to frequencies of 300 GHz and more. The low-frequency RF spectrum increases the operating range with large antenna dimension but reduced range of operating frequency. UWB communications systems with very large relative and/or absolute bandwidth are mandated with low power spectral density to allow their use as overlays over existing systems. The interference between UWB devices and narrowband devices which hampers the overall performance of the communication systems is mitigated using some novel modifications on the antenna structures.
