The suspended stripline BPF of cross coupling design using quasi-lumped approach

In this paper, quasi-lumped design of a BPF using the suspended stripline (SSL) is demonstrated. The proposed SSL BPF has achieved the benefits of size compactness, extremely low insertion losses, low dispersion, high operation frequency, and sometimes the wide stopband bandwidth. A cross-coupling structure is introduced in filter between the I/O to create transmission zeros by the passband for the signal selectivity enhancement. The proposed SSL filter is analyzed by the derived equivalent circuit model based on lumped elements approach. The plotted curves of calculated data obtained from equivalent circuit models and those from the commercial electromagnetic software vs. the dimensions of the SSL filter are given in the figures. Experiment is conducted to verify the filter's performance.