UWB bandpass filter with sharp rejection and narrow notched band.

A novel ultra‐wideband (UWB) bandpass filter with sharp rejection and a narrow notched band is presented. This filter is designed using a multiple‐mode resonator (MMR) which consists of a ring resonator and a stepped‐impedance stub. The MMR has six resonance frequencies and three transmission zeros (TZs). All three TZs are close to the resonance frequencies, thus creating sharp roll‐off and narrow notched bands. Different passband bandwidths and notched bands can be obtained by tuning the stepped‐impedance admittance ratios. The simulated and measured results demonstrate that this simple bandpass filter has 97.3 and 30.6 dB/GHz attenuation slope at the lower and upper transition bands, respectively. The 3 dB notched band is from 5.6 to 5.8 GHz with 10.3 dB insertion loss at 5.7 GHz. [ABSTRACT FROM AUTHOR]