In this paper, using the conductor-backed coplanar waveguides (CBCPWs) and the slow-wave stepped-impedance resonators, a second-order and a fourth-order inductively/capacitively coupled bandpass filters are designed, implemented, and measured. For second-order bandpass filter, two H-shaped defected ground structure (DGS) patterns are etched on the backside metallic ground planes of the input and output feedlines, it is found that two attenuation poles exist on both sides of the passband. When compared to the fourth-order bandpass filter without H-shaped DGS, the second-order bandpass filter with H-shaped DGS has compact size and comparable rolloff at the edges of the passband. In addition, the measured results of the filters agree well with the simulated ones.
Chang, Jiunn-Jye and Sie, Chih-Hong
"INDUCTIVELY/CAPACITIVELY COUPLED CONDUCTOR-BACKED COPLANAR WAVEGUIDE BANDPASS FILTERS USING SLOW-WAVE STEPPED-IMPEDANCE RESONATORS,"
Journal of Marine Science and Technology: Vol. 17:
2, Article 8.
Available at: https://jmstt.ntou.edu.tw/journal/vol17/iss2/8