A miniaturized UWB bandpass filter using open stub T- shaped line loaded resonators

In this paper, a miniature planar ultra-wideband (UWB) bandpass filter has been proposed and simulated by using loop resonators. The occupied size of the proposed filter is 123 mm² The studied filter is not only compact but also delivers excellent scattering parameters with magnitude of insertion loss, S₂₁ lower than 0.09dB and return loss found better than 20 dB. The bandpass filter has 3-dB fractional bandwidth of 65% of center frequency (5.46 GHz), in the range of 3.7 GHz to 7.22GHz. A new feature of the loop resonator filter is constructed by ring resonator and T-shaped stub loaded at the line center.