Direct-coupled cavity bandpass filters with Chebyshev response are studied and realized. using the technique of planar substrate-integrated waveguide (SIW) for the purpose of high-density integration and cost reduction. Using a general mode-matching technique. the scattering matrix of waveguide bifurcation-type discontinuity and asymmetric iris are established and analyzed. https://www.roneverhart.com/Bearbrick-WALL-E-400/