Cross-Coupled Suspended Stripline Trisection Bandpass Filters with Open-Loop Resonators

We present two bandpass trisection filters with asymmetrical characteristics in the suspended substrate technology. The open-loop resonators are based on a meandered half-wavelength line topology thus allowing a significant size reduction. The design of these filters follows two steps: A synthesis based on the extraction of the general cross-coupled folded network parameters and coupling matrix, then the relationship between the resonators' spacings and coupling coefficients is obtained thanks to full-wave electromagnetic simulations. Transmission zeros on both sides of the passband can be achieved.