Multilayered multiconductor stripline resonator and its application to bandpass filter with wide stopband

A multilayered, multi-conductor stripline resonator is proposed. It is shown that increase in the number of conductors leads to increase the unloaded Q-factor and decrease the resonant frequency, with increasing the effects for thinner dielectric interlayer. Application of the resonator to the bandpass filter enables designing bandpass filters with very wide and deep stopbands. To prove this, a 4-pole bandpass filter, having central frequency 360 MHz and an overall size of 15.5 × 31.75 × 8.45 mm³, was designed and fabricated.