High Selectivity Fifth-Order Wideband Bandpass Filters With Multiple Transmission Zeros Based on Transversal Signal-Interaction Concepts

Two high selectivity fifth-order wideband bandpass filters (BPFs) with multiple transmission zeros based on transversal signal-interaction concepts are proposed in this paper. Two transmission paths consisting of a shorted stub and two open coupled lines are used to realize signal transmission from Port 1 to Port 2. Two fifth-order wideband passbands with six and ten transmission zeros from 0 GHz to 2f₀ (f₀ is center frequency of the passband) can be achieved respectively due to the superposition of signals of the two transmission paths. Two prototypes with 3-dB fractional bandwidths of 61.7% (2.07-3.92 GHz) and 48.2% (2.3-3.76 GHz) are designed and fabricated for demonstration. Good agreement can be observed between simulated and measured performances.