A compact wideband filter based on a grounded transversal resonator

In this work, a grounded transversal resonator is presented which exhibits tri-mode behaviour and provides two transmission zeros. The proposed resonator is analyzed and used to design a very compact low-loss wideband bandpass filter with a central frequency of 4 GHz. The fabricated filter exhibits 3-dB fractional bandwidth of 83.5%, good in-band and out-of-band performances and a compact size of only 0.29λ_g × 0.19λ_g, where λ_g denotes the guided wavelength on the given substrate at the central frequency.