Ultra-wideband (UWB) bandpass filters with multiple notched bands using asymmetric dual-line coupling structure

A novel ultra-wideband (UWB) bandpass filter (BPF) with multi notched bands has been presented. For notched band implementation in UWB BPF, an asymmetric dual-line coupling structure has been presented and used in the UWB BPF, which can generate multi notched bands. The parameters of this asymmetric structure have been investigated in detail. A UWB BPF with multi notched bands has been designed, fabricated, and measured. The measured results agree with the predicted ones closely. The two notched bands of the BPF centered at 4.95 and 6.55 GHz have 10-dB FBW of about 2.2% and 4.6%, respectively.