Grating-Tuner in Dielectric Image Line for Integrated Millimeterwave Circuits

It is shown that concentrated line discontinuities for matching purposes, like e.g. a sliding screw, in open dielectric image line can cause heavy radiation losses. A distributed reflection structure which can be used as a "sliding screw"-tuner with neglectable radiation losses in dielectric image line (as well as in other open dielectric waveguides) is investigated. The structure consists of a periodically metalized dielectric sheet (grating structure), which can be moved along the dielectric image line.