Distributed transmission line structure

摘要

A distributed transmission line structure (10) includes a ground plane (26) affixed to a substrate (12). The substrate (12) is formed of a generally nonconductive material. A first metallic strip (14) is affixed to the substrate (12) and is electrically connected to the ground plane (26) through a first through-hole (34). A second metallic strip (16) is affixed to the substrate (12) and is spaced apart from the first metallic strip (14) by a gap (28) and is electrically connected to the ground plane (26) through a second through-hole (38). A dielectric layer (20) overlies the substrate (12), the first metallic strip (14), and the second metallic strip (16). A third metallic strip (18) is affixed to the dielectric layer (20) and is disposed to overlie the gap (28). The third metallic strip (18) has a width less than the gap (28). The impedance of the distributed transmission line structure (10) is substantially constant over a predetermined range of thickness of the dielectric layer (20).