Compact UWB bandpass filter with two notched bands based on electromagnetic bandgap structures

A novel and compact ultra-wideband (UWB) bandpass filter with dual narrow notched bands based on two mushroom-type electromagnetic bandgap (EBG) structures is presented. The UWB BPF comprises two coupled lines which are coupled to the open-ended coplanar waveguide on the ground and two EBG structures near the feedline. By simply adjusting the dimensions of the two EBG structures, the centre frequencies of the notched bands can be allocated at 5.2 and 5.8 GHz, respectively. The UWB bandpass filter has been simulated, fabricated and measured, with good agreement between the simulated and measured results. The two notched bands of the BPF centred at 5.2 and 5.8 GHz have 10 dB fractional bandwidths of about 5.7 and 3.4%, respectively.