Compact dual-band BPF with wide stopband using stub-loaded spiral stepped-impedance resonator

A compact dual-band bandpass filter (BPF) with wide stopband performance using stub-loaded spiral short-circuit λ /4 stepped-impedance resonator is proposed. Spiral configuration has been used for compactness of filter. Both passbands can be controlled individually by changing the geometric parameters of resonator. Multiple transmission zeros provide high selectivity to both passband and extend stopband up to 3 GHz. The filter has compact size of 0.06 λ g × 0.09 λ g . A dual-band BPF has been designed and fabricated for terrestrial trunked radio (TETRA) band and global system for mobile communication applications.