A Dual-Mode Bandpass Filter With Enhanced Capacitive Perturbation

摘要

A dual-mode ring bandpass filter with two pairs of capacitors has been designed. The capacitors are used to control the location of the even- and odd-mode frequencies independently, allowing weak coupling for narrow-band filter design with realizable capacitance values. Theoretical expressions have been derived for these frequencies. A 4 bandwidth bandpass filter centered at 1.9 GHz was designed and tested with good agreement between the-oretical and measured results.