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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

What Is a Directional Coupler?

Learn what a directional coupler is and how it measures forward and reflected RF power.

Getting Started HF Fundamentals Reviewed 2026-07-14
Short Answer: Learn what a directional coupler is and how it measures forward and reflected RF power.

Explanation

Overview A directional coupler is an RF device that samples radio frequency energy traveling in one direction while rejecting energy traveling in the opposite direction. Directional couplers are fundamental components in SWR meters, wattmeters, and many RF measurement systems. Primary Functions Measure forward power. Measure reflected power. Determine SWR. Monitor transmitter performance. Applications SWR meters. RF wattmeters. Laboratory test equipment. Automatic antenna tuners. Broadcast transmitters. Advantages Non-invasive measurement. High measurement accuracy. Continuous monitoring. Applied to Chameleon Products Directional couplers are used in many instruments that verify proper operation of Chameleon antenna systems during installation and troubleshooting. Related Articles What Is an SWR Meter? What Is Forward Power? What Is Reflected Power? What Is Return Loss? Related Products All Chameleon Antennas

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.