A Compact Quint-Band Bandpass Filter with Coupled-Line Structure

In this article, a quint-band bandpass filter is designed based on planar coupled line structures. The proposed filter is utilizing frequency transformation techniques, not only achieves precise and stringent bandwidth specifications but also benefits from a compact overall size due to the closely coupled structure. In order to confirm the validity of our analytical approach, simulations were conducted on a basic planar filter using microstrip technology, and the simulation outcomes, showing strong agreement with theoretical analyses, affirmed the precision and dependability of our analytical methodology.