75 Ohm Coax

75 Ohm Coax for Amateur Radio

Antennas and Their Natural Impedances
Antenna Type Typical Feedpoint R Better Match?
Half-wave dipole (≥¼λ height) 60–85 Ω 75Ω wins
Half-wave dipole (low height) 40–60 Ω Depends on height
Inverted-V (shallow droop, 120°) 50–68 Ω Close to a wash
Inverted-V (steep droop, 90°) 40–55 Ω 50Ω wins
Full-wave loop (current-fed) 100–120 Ω 75Ω wins
¼λ vertical, horizontal radials ~36 Ω 50Ω wins
¼λ GP, 45° drooped radials ~50 Ω 50Ω wins
Vertical dipole ~73 Ω 75Ω wins
Yagi / beam 20–35 Ω 50Ω wins
Impedances vary with height above ground, element dimensions, and construction details.