A miniature quad-band band pass filter using modified stepped impedance resonator and parallel resonating stubs for satellite communication

A miniature planer quad-band bandpass filter (BPF) using stepped impedance resonator with loadings stubs, parallel resonating stubs and defected ground structure is proposed. Loading stub used to give extra parameters to tune resonant frequency. Three parallel resonating stubs are used to generate three extra pass bands by shifting higher order resonant mode to desired frequency bands and make quad-band BPF. Stop band performance improved by cross coupling of parallel feed structure and SIR, which generates transmission zeros at edge of lower and upper stop band of each band. Defected ground structure provides superior band and out-of-band performance of filter. Filter can be utilized for four bands listed as 4.4-4.5GHz (fixed and mobile communication), 5.15-5.25Ghz (fixed satellite/WLAN/Wi-Fi/aeronautical navigation), 5.925-6.425GHz (commercial c-band satellite communication) and 7.55-7.75Ghz (fixed satellite communication). Designed filter have some commendable features like closely spaced, highly isolated bands (deep zeros between bands), miniature sized (180 mm2), low loss performance, adequate stopband and cost efficient structure. Alumina (Epsilon=9.9) used as substrate and Simulation of design done using commercial software CST microwave studio 2015.