Coupled-line dual-band bandpass filter with compact structure and wide stopband

A novel dual-band bandpass filter with a compact structure and a wide stopband is proposed. The total structure includes coupled-line stubs and coupled-line connected sections, leading to a compact circuit. This proposed filter can be implemented easily by using single-layer microstrip technology. The measured results of a prototype filter show that it can operate at both 1.32 and 2.67 GHz and up to the 8 GHz 15 dB stopband.