Wideband Bandpass Filter using Half Wavelength Grounded Coplanar Waveguide Resonator

This paper reports on the design of a grounded coplanar wideband (CPW) bandpass filter using half-wavelength resonators. CPW half-wavelength resonators are not commonly used for design wideband filter because it is difficult to achieve strong input/output couplings. Here, step impedance is used to couple the input of the filter to the 1st resonator and also the output of the filter to the n-th resonator to mitigate this difficulty. A theoretical model of the step impedance input/output coupling will be presented, which will be verified with a simulation model. Wideband bandpass coupled resonator filter responses will be presented for both simulated and experimental results. The results exhibit strong agreement between theoretical and measured results.