Compact Low Pass Filter with Ultra-Wide Pass and Stopbands Using Stepped Impedance Resonators and Novel Techniques

The design procedure of a compact ultra-wideband (UWB) stepped impedance resonator (SIR) low pass filter (LPF), is presented in this paper. A SIR LPF with 15.5 GHz cutoff frequency miniaturized by meander line technique is designed and it is shown that offsetting the stepped impedance resonators, as well as indenting the tap location greatly improve rejection bandwidth. By cascading multiple filters the passband is increased while maintaining good rejection bandwidth. The proposed filter is simulated in EM software, fabricated, and tested on a high dielectric ceramic. The results show an improved stopband and passband performance compared with similar topologies with a drastic reduction in filter size.