Cut lengths for quarter- and half-wave stubs — harmonic notches, phasing lines, and matching sections.
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electrical quarter wave at this frequency in this cable
¼-wave OPEN stub (nothing on the far end), teed into the line: dead short at the cut frequency — notches that frequency and its odd multiples.
¼-wave SHORTED stub (far end soldered): passes the cut frequency untouched, but notches its even harmonics — the classic "20m stub" that kills your 10m harmonic in multi-op contests.
½-wave sections repeat whatever impedance is at the far end — useful as measured extension lines.
Cut ~2% long and trim while watching an analyzer; connectors and the tee eat a little length.
Physical length = electrical length × velocity factor. Foam cables are "faster," so their stubs are physically longer.