Patent ID: 8576026

Claim:
A band-pass filter including a plurality of frequency band channels each having first and second balanced ports and first and second unbalanced ports, each frequency band channel comprising: a first split-ring resonator having a first end terminal coupled to the first balanced port and a second end terminal coupled to the second balanced port, the first end terminal and the second end terminal of the first split-ring resonator defining a first gap in the first split-ring resonator; a first capacitor coupled between the first and second end terminals of the first split-ring resonator; a second split-ring resonator having a first end terminal coupled to the first unbalanced port and a second end terminal coupled to the second unbalanced port, the second split-ring resonator being disposed within a first distance of the first split-ring resonator to induce magnetic coupling between the first and second split-ring resonators, the first end terminal and the second end terminal of the second split-ring resonator defining a second gap in the second split-ring resonator; a second capacitor coupled between the first and second end terminals of the second split-ring resonator; a third split-ring resonator disposed within a second distance of the first split-ring resonator and within a third distance of the second split-ring resonator to induce magnetic coupling between the first, second, and third split-ring resonators; and a third capacitor coupled between a first end terminal and a second end terminal of the third split-ring resonator, the first end terminal and the second end terminal of the third split-ring resonator defining a third gap in the third split-ring resonator, wherein the third gap is disposed relative to the first and second gaps such that a first vertical plane that passes through both the first and second gaps is substantially perpendicular to a second vertical plane that passes through the third gap, and wherein the first split-ring resonator is substantially symmetric to the second split-ring resonator about the second vertical plane.