BALUNs and UNUNs

Our current-type BALUNs, UNUNs, and EFHW transformers cover antennas from 1.8 to 450 MHz — broadband units spanning most of the HF spectrum, and single-band units tuned for exceptional performance over a narrow range. Every one is a current-type design, expertly wound and measured in-house for maximum resistive choking impedance across your operating band — because current balance, not a voltage spec that looks good on paper, is what keeps common-mode current off your feedline. Learn why in About BALUNs.

Which one do you need?

1:1 BALUN (50:50) — for coax-fed dipoles and Yagis. Provides current balance at the feed point and stops feedline radiation. The default choice for a standard 50-ohm balanced antenna.

4:1 BALUN (200:50) — for off-center-fed (OCF) dipoles and other balanced antennas whose feed-point impedance sits near 200 ohms.

9:1 / 4:1 UNUN — for non-resonant random-wire and vertical antennas, such as popular 27 ft or 43 ft wires, fed against a ground or radial system.

EFHW transformers (49:1 / 56:1) — the matching transformers for end-fed half-wave antennas. Note these are UNUNs, not baluns — see All About EFHW Antennas for the full story.

Not sure which fits your antenna? The rule of thumb is simple: balanced antenna near 50 ohms ? 1:1 BALUN; balanced antenna near 200 ohms ? 4:1 BALUN; single unbalanced wire or vertical ? UNUN; end-fed half-wave ? EFHW transformer. When in doubt, ask — I answer the technical questions personally.