Design of dual-band net-type bandpass filter

In this paper, a new dual-band net-type bandpass filter is designed, fabricated, and experimentally verified using dual-band and single-band net-type resonators. The dual-band net-type resonator is designed to operate at two closely specified resonant frequencies, f₁ and f₂. Then incorporating with single-band net-type resonators, a dual-band filter can be implemented using the design concept of adding extra coupled resonators. To reduce the circuit size, two types of resonators are further folded to become a square box shapes. The measured results of the developed filter are in a good agreement with the simulated results by full-wave electromagnetic simulator. Moreover, the developed filter not only has an excellent mid-band rejection, but also provides a wide stopband suppression.