Novel wideband bandpass filter-based on anti-coupled line

A simple wideband bandpass filter based on anti-coupled lines circuit configuration was proposed. This filter configuration was composed of a length of bending anti-coupled line and an open-circuit transmission-line stub. The proposed filter structure was analyzed by using the even-mode and odd-mode analysis method and simulated. The results show that by selecting the appropriate circuit parameters, the filter can appear six transmission zeros. Two designed bandpass filters(Filter-A and Filter-B) were simulated and produced. The results are as follows: when the center frequencies of the two filters are 3 GHz, the percentage bandwidths of Filter-A and Filter-B are 47% and 40%, respectively. The measured results show that the filter has certain advantages on the percentage bandwidth under the lower insertion loss in band and better group delay.