ENGINEERING ANSWER
Distributed filters use geometry and coupling as circuit elements. Their response depends on gaps, line widths, discontinuities, material model and fabrication tolerances, often more strongly than a simple through-line.
What to decide before release
Use a circuit synthesis as a starting point, followed by electromagnetic simulation of the complete layout. Sweep dimensions that the fabricator can realistically vary and provide a measurement plan with suitable reference planes.
Checks to put in your design brief
- Model coupling gaps
- Include launches and housing
- Run a dimensional tolerance sweep
Important distinction
Do not convert a schematic into production artwork using only a nominal Dk and ideal transmission-line sections.
Sources & basis
Material facts follow the cited source. Design checks are preliminary guidance, not supplier process instructions.