A novel balanced BPF using the folded half-mode substrate integrated waveguide has a central frequency of 4.65 GHz with 0.55 GHz BWin-band insertion loss of 2.2 dB. The size of an FHMSIW is about 1/4 of the substrate integrated waveguide (SIW). The common-mode rejection levels are greater than 40 dB over a wide frequency range.