Compact two pole bandpass filter using symmetrical composite right/left handed transmission line with vias

A compact two-pole bandpass filter based on the composite right/left-handed (CRLH) metamaterial transmission line structure is proposed in this paper. In detail, subwavelength resonators are realized through the zeroth order resonance (ZOR), and inverter structures are proposed to control the coupling between neighbouring ZOR resonators. The proposed technique is validated by the EM predictions, the proof of metamaterial properties with the ZOR field distributions and extracted constitutive parameters, and measurements. Size independent resonance property of the ZOR combined with homogeneity condition of the LH TL unit cell is utilized in the size reduction of bandpass filter. It is found that the suggested method enables the remarkable size reduction from the conventional filters such as the parallel coupled type which is designed on the basis of the half-wavelength resonance. The proposed technique is also validated by the experimental results.