Modeling and Susceptibility Study of Ring Resonator Bandpass Filter for Wireless Applications

This article presents a T-type stub loaded ring resonator bandpass filter with defected ground structure (DGS) for applications in wireless communication systems. Two H-shaped DGS have been used at the ground plane to suppress spurious frequency response above the passband. Parametric analysis of the proposed filter has been done using IE3D 15.2. Measured result shows a fractional bandwidth of 13.8%, centered at 3.3 GHz, and sharpness factor of 160 dB/GHz. Better than 20 dB out-of-band rejection level has been achieved from 3.64 to 7 GHz. A susceptibility test has been performed to check whether the filter will be able to operate satisfactorily in the presence of interfering signals. To validate the simulated results it is fabricated and tested. The simulated data show a good agreement with measured data.