Miniaturized Microstrip Bandpass Filters Using Novel Stub Loaded Resonator

In this paper, a novel structure is proposed to design two compact microstrip bandpass filters operated at 2.39 GHz and 5.73 GHz, which their sizes are 44 mm(2) and 14 mm(2), respectively. Miniaturization, resonance frequency tuning and harmonics attenuation methods are presented. Low insertion losses and wide fractional bandwidths are achieved. The obtained insertion losses and fractional bandwidths of the 2.39 GHz and 5.73 GHz filters are 0.27 dB, 0.19 dB, 46%, and 44%, respectively. Also for both filters, the second and third harmonics are attenuated. The proposed filters are fabricated and measured and there is a good agreement between the simulation and measurement results.