Microstrip Filters on Codirectional Hairpin Resonators with Split Working Attenuation Poles

In this paper, we study the potential selective capabilities of various structures of microstrip filters with a limited number of half-wave codirectional hairpin resonators. It is shown that in these structures it is possible to realize a significant number of working attenuation poles at finite frequencies. The mechanisms of the attenuation poles formation, splitting and joining are studied to ensure the required attenuation level in the specified stopbands.