Design of compact UWB Band Pass filter using radial stub loaded resonator and cross-shaped coupled lines with improved out-of-band performance and sharp roll-off

In this paper, a compact ultra-wideband (UWB) band-pass filter with sharp roll-off and improved out-of-band performance is designed and manufactured. In the proposed structure, modified one quarter-wavelength cross-shaped coupled lines (CCLs), and also radial stub loaded resonator (RSLR), are implemented in order to reduce the total size of the UWB BPF. The RSLR is able to control two tuneable transmission zeros (TZs) separately and the CCLs can be properly designed so that the unwanted pass band is rejected. A prototype of the proposed UWB BPF is fabricated and tested. The measured results are in good agreement with the simulated data and the proposed structure shows a sharp selectivity and good filtering performance in the frequency band of interest.