I am doing filter design using microstrips. I have assigned airbox from T+H, but error appears when airbox is assigned as radiation boundary. (T-thickness of gnd, H-thickness of substrate). A radiation boundary face has solid objects with SolveInside on both sides of it. Only substrate has solve inside set in the design..What is the problem here?
did you reassign a conductor (bottom) as radiation instead of conductor? double check ports. something is wrong in the -20dB case. look through the help pages about radiation boundaries for the conditions you should meet. there's something about minimum distance from conductors. Also with no boundaries assigned the outer box is perfect conductor.