Meander lines are promising slow-wave structures (SWSs) for millimeter-wave traveling-wave tubes (TWTs) due to low-cost manufacture, low-voltage operation, and high interaction impedance. However, experimental results on meander lines are rare in the literature. Phase velocity and interaction impedance
are the most important parameters for the design and characterization of TWT SWSs. Their experimental determination in meander lines is crucial for validating simulations and developing new topologies. Based on a new theoretical model, this article presents an experimental procedure to determine the phase velocity and the interaction impedance. The method is validated on four different Ka-band (33–37 GHz) meander-line SWSs, including two of a novel topology