Low-loss band-pass filter using bilaterally metal-loaded triplate strip transmission line at 30 GHz

A bilaterally metal-loaded tri-plate line filter with a three-pole 0.1 dB ripple Chebyshev response was successfully designed and fabricated to realize a low loss printed filter at 30 GHz. It was obvious that the transmission characteristics of the filter was relatively unaffected by the skin effect of the under surface of the metal strips, because the two center conductors were the same voltage. And moreover, this filter has non-radiating nature due to its symmetrical structure even if the filter is inserted in a width-enlarged waveguide, and hence, the low-loss nature. Next step of this research will be to improve the transition performance of this filter.