Novel Tri-Band Bandpass Filter With Independently Controllable Frequencies, Bandwidths, and Return Losses

A novel kind of tri-band bandpass filter (BPF) is presented, which is based on the dual composite right- and left-handed resonator. The proposed tri-band BPF is very compact with over 30% size reduction over the previously published ones. The center frequencies and bandwidths can be controlled independently with large flexibility. In addition, the return losses can also be adjusted independently, resulting in the optimal impedance matching for the proposed designs. Finally, one tri-band BPF is designed for demonstration, which simultaneously exhibits compact circuit size and preferable in-band performances. Good agreement between the measured and simulated results is observed, verifying the validity of the design strategies.