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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

What Is a 4:1 Balun?

Learn what a 4:1 balun is, how it works, and when it should be used with balanced amateur radio antennas.

Feed Lines & RF Components Matching & Isolation Devices Reviewed 2026-07-14
Short Answer: Learn what a 4:1 balun is, how it works, and when it should be used with balanced amateur radio antennas.

Explanation

Overview A 4:1 balun is a balanced-to-unbalanced transformer that provides both balanced-to-unbalanced conversion and an impedance transformation ratio of approximately 4:1. It is commonly used to connect balanced antennas having feed-point impedances near 200 ohms to standard 50-ohm coaxial cable. Primary Functions Balanced-to-unbalanced conversion. Approximately 4:1 impedance transformation. May reduce common-mode current when using a current balun design. Typical Applications Loop antennas. Folded dipoles. Doublets with matching networks. Certain multiband wire antennas. Important Considerations The antenna's actual feed-point impedance changes with frequency. A 4:1 balun is not appropriate for every balanced antenna. Current balun designs are generally preferred for most amateur radio applications because they maintain better current balance. Applied to Chameleon Products Some Chameleon antenna configurations and accessories use 4:1 matching devices where the antenna design and feed-point impedance make them appropriate. Related Articles What Is a Balun? What Is a 1:1 Balun? What Is a Current Balun vs a Voltage Balun? What Is Characteristic Impedance? Related Products Selected

The exact result depends on the complete station: frequency, geometry, feed line, matching network, return-current path, environment, operating power, and the reference plane of any measurement. A low SWR establishes an impedance relationship at that point; it does not by itself prove efficiency, radiation pattern, compatibility, or safety.

What to Verify

  • Use the newest official product guide or primary service documentation.
  • Confirm the exact model, revision, components, configuration, and operating conditions.
  • Begin tests at low power and change one variable at a time.
  • Do not infer compatibility from connector or thread fit.

Learn Next

  • Antenna Selection: A Mission-First Decision Guide
  • Engineering Design Tradeoffs in Portable HF Antennas
  • Antenna Measurement Reference Planes
  • Understanding Common-Mode Current

Source note: Independently synthesized with reference to The ARRL Handbook for Radio Communications, 99th edition (2022), and The ARRL Antenna Book for Radio Communications, 24th edition (2019). Verify changing regulations, services, software, specifications, availability, and safety requirements against current primary sources.