Cost effective printed filter using BIT line at millimeter-wave frequencies

The bilaterally metal-loaded tri-plate transmission line (BIT line) band-pass filter was designed and fabricated at 30GHz by using the FR-4 substrate for the purpose of cost-effectiveness. And moreover, the filter was designed at 60GHz by expanding the design guide at 30 GHz. In the design procedure, Prof. Matthaei's theory using inverter parameters of the transmission lines having differential transmission lines at input and output ports was applied. The BIT line filter was also designed by using the glass-fiber PTFE substrate to compare the filter made by FR-4 substrate.