WP4TZV.
MHz

Antenna Model · Designer · closed-form

Random / Long Wire

length = factor × λ × k  ·  λ = 41.93 m @ 7.150 MHz

FIG.1 · RANDOM / LONG WIRE feedHalf-wave to avoid 19.916 m
Half-wave to avoid
19.916m
Accuracy note
Not a resonant cut — match with a tuner.
Method closed-form Cite ARRL Antenna Book Feed High and reactive — feed through an antenna tuner (a 9:1 unun helps an end-fed random wire).
  • A random wire is deliberately not resonant; a tuner does the matching.
  • Avoid exact half-wave multiples of your bands (shown) — they present an awkward high impedance.
  • Longer is generally better; add a counterpoise/radial.