A Design of Cascaded Trisection Bandpass Filter Using The Meander line Embedded in SIR

The embedded meander line in stepped-impedance resonator (SIR) is proposed to design narrow bandpass filter with a good stopband characteristics. The design differs from the general SIR configuration in that the microstrip lines are bent at the location of the maximum magnetic field density. As a result, the resonators have high external quality factors by themselves, since the factor is closely concerned with electric component of the resonator. Moreover, the SIR filter size is heavily reduced by electric coupling between the meander section and the side with open gap. The main application of the proposed structure is in realizing miniaturization in the wibro transceiver band. Sizes of resonators are 7.3 mm×4.95 mm×0.635 mm, 8.6 mm×5.5 mm×0.635 mm, respectively. Measured data of the CT filter indicate 2.8 dB of insertion loss at 2.32 GHz, as well as 18 dB of attenuations at refraction frequencies of 2.37 GHz, respectively. Key-Words: Microstrip line, SIR, Bandpass filter, Meander line, Miniaturization circuits