Abstract :
In this paper, the applications of shunt open stubs are reported based on asymmetric half-wavelength resonators structure. To demonstrate the design ideas, the analysis methods of ABCD matrix and equivalent circuit are used. The multi-band bandpass, miniaturization and harmonic suppression by application of the shunt open stubs are demonstrated. The measured insertion loss of the dual-band filter with the center frequency of 1.9 and 5.8 GHz is less than 2.7 dB. The insertion loss of the tri-band filter with the center frequency of 1.5, 4 and 6.3 GHz is less than 2.7 dB. Furthermore, a compact bandpass filter with size around 12.3 mm*11.5 mm is designed and fabricated. The bandwidth of the filter is 120 MHz with the center frequency of 2.4 GHz and the insertion loss is less than -3 dB. Especially, the insertion loss is less than -20 dB from 2.8 GHz to 7 GHz. For the filters above, the simulated results and the measured results agree well.
