Balun-BPF using magnetically coupled interdigital-loop resonators

In this paper, we proposed the Balun-BPF (band pass filter) using the magnetically coupled resonators. The proposed Balun-BPF is a deformation of the transformer which operates like the ideal Balun in low frequency. The conventional coupled-resonator filter design theory was used for the design of a Balun-BPF. Moreover, the Interdigital-loop resonator was used to miniaturize the Balun-BPF. This Balun-BPF operated in a 2.4~2.5 GHz band, generally used in the wireless communication. Experimental measurements are also presented to validate the theory and EM simulations.