A Novel Dieletric Slot Stripline Structure for Millimeter Wave Flexible Printed Circuit

While FPC (flexible printed circuit) operates at higher frequency approaching 10 GHz to millimeter wave band, the larger insertion loss becomes a challenging issue. A novel transmission line structure is proposed for FPC, in which two metal planes are placed above and under the signal line to provide anti-interference, also the areas around the signal line are slotted to enlarge the portion of air in transmission medium to reduce insertion loss. It is termed as "dielectric slot stripline", whose pilot samples for proof of concept are manufactured and measured. Results show that the proposed structure effectively improves transmission performance compared to coplanar waveguide used in FPC. Although design optimization including layout and connector is still needed, this paper proves an initial model towards a promising candidate for high-speed and low-loss transmission line solution in millimeter wave FPC.