Designs of suspended stripline filters using quasi-lumped elements approach

In this paper, a quasi-lumped design of filters using the suspended stripline (SSL) is demonstrated. The proposed SSL filters have achieved the benefits of size compactness, extremely low insertion losses, low dispersion, high operation frequency, and sometimes the wide stopband bandwidth. The filters presented in this paper include low-pass filters (LPFs), high-pass filters (HPFs), and a sample bandpass filter (BPF). The BPF is implemented by a cascade of an LPF and an HPF, which together form an ultra-wideband (UWB) BPF that covers a frequency range from 3.1 to 10.6 GHz. All of the mentioned filters are analyzed by their equivalent circuit models based on a lumped elements approach. The plotted curves of the calculated data obtained from equivalent circuit models and those from the commercial electromagnetic software vs. the dimensions of the SSL filters are given in the figures. Experiments are conducted to verify the filters' performance.