NOVEL COMPACT ELLIPTIC-FUNCTION NARROW-BAND BANDPASS-FILTERS USING MICROSTRIP OPEN-LOOP RESONATORS WITH COUPLED AND CROSSING LINES

Novel compact elliptic-function narrow-band bandpass filters have been designed and fabricated. This new configuration consists of two ident ical microstrip open-loop resonators with coupled and crossing lines. A theoretical investigation has confirmed that this novel configuratio n is capable of providing elliptic-function filtering, Furthermore, th e feasibility of this filter is verified experimentally. Centered at 2 .039 GHz, the fabricated microstrip bandpass filter shows a measured 3 -dB bandwidth of 2% and two deep notches in its stopband. In addition, the main circuit of this filter occupies only 2.5 cm x 1.5 cm using a substrate with dielectric constant of 10.5, making it very attractive for applications in the mobile and personal communication systems (PC S's).