Novel microstrip bandpass filters with transmission zeros

Some design methods for band-pass filters based on halfwavelength resonators have been proposed. The main feature of these methods is that n or n + 1 transmission zeros can be generated for a structure composed of n resonators. To demonstrate the usefulness of the proposed filter structures, three kinds of two-pole compact microstrip hairpin filters are designed and fabricated. Good agreement between measured and simulated data has been demonstrated.