A processing system is disclosed having a radio frequency (RF) power system coupled to a process chamber via a transmission line. The RF power system is configured to generate RF power at a RF operating frequency. The processing system also includes a resonant structure arranged within the plasma processing chamber that includes at least one resonant substructure configured to resonate according to at least two different resonant modes when at least one resonant frequency associated with at least one of the modes is at or near the RF operating frequency.