Notch bandwidth and filter order trade-offs in band-notched monopole antennas for UWB applications

In this paper, we have optimized the performance of both the slot notched and compact coplanar waveguide (CRW) cell (CRCC) notched monopoles to eliminate the local oscillator (LO) leakage, but their presence could impact the overall UWB performance. The added slot in the patch and the CRCC in the feed-line of the planar monopole antenna act as 1st order and 2nd order band-stop filters respectively. Their rejection bandwidth and associated filter order number would affect the time domain UWB signal performance. It has been demonstrated that when narrowing the notch bandwidth and increasing the filter order, the first pulse amplitude (FPA) is higher, which could benefit the UWB positioning system, however, it renders longer power delay spread (PDS), which is undesirable for UWB communication system. The trade-off between FPA and PDS has been investigated and utilized to optimize the band-notched planar monopole design.