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

In this work, we addressed the problem of local oscillator leakage from the mixer in our UWB localization system. The leakage could be remedied either by using an integrated filter or using a band-notched antenna. Here we have utilized a band notched antenna and analyzed the effects of the filter order on the pulse amplitude and delay spread. It was found that the filter order and rejection bandwidth could be optimized to satisfy the specific amplitude and pulse spread requirements. Four UWB monopole antennas were designed, fabricated and measured. The measurement results were in good agreement with the simulation results. We showed that using a higher order filter allows for adequate rejection bandwidth and higher rejection levels while keeping the first pulse amplitude almost constant, but the power delay spread increases accordingly.