Coplanar waveguide bandpass filter with hollow-T shaped transmission-line resonator for multiple spurious suppression

In this work, the coplanar waveguide (CPW) hollow-T shaped transmission-line resonator is proposed, which is achieved by introducing a series short-stub at the center of a quarter-wavelength transmission-line resonator. It can be used to implement CPW bandpass filter with additional transmission zeros for spurious suppression. Specifically, a 4th-order CPW bandpass filter centered at f₀ = 2 GHz with multiple spurious suppression up to 5f₀ is demonstrated.