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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

What Is FT4?

Learn what FT4 is, how it differs from FT8, and when it is best used in amateur radio.

Digital Communications Weak-Signal Digital Modes Reviewed 2026-07-14
Short Answer: Learn what FT4 is, how it differs from FT8, and when it is best used in amateur radio.

Explanation

Overview FT4 is a weak-signal digital communication mode developed by the WSJT development team. It uses many of the same operating concepts as FT8 but is optimized for faster contacts. By reducing transmission cycle time, FT4 allows operators to complete more contacts during contests and periods of rapidly changing propagation. FT4 vs FT8 Feature FT4 FT8 Transmission Cycle Approximately 7.5 seconds Approximately 15 seconds Operating Speed Faster Slower Weak-Signal Performance Very Good Excellent Contest Suitability Excellent Good Advantages Rapid QSOs. Efficient contest operation. Lower operating time per contact. Compatible with WSJT-X. Operating Considerations Requires accurate computer clock synchronization. Maintain clean transmitted audio. Use appropriate digital-mode power levels. Monitor band activity before transmitting. Applied to Chameleon Products Chameleon HF antenna systems provide broadband multiband performance that supports FT4 operation for portable operators, contest stations, and fixed installations. Related Articles What Is FT8? What Is JS8Call? What Is Digital Mode Duty Cycle? What Is WSJT-X? Related Products CHA MPAS 2.0 CHA LEFS Series CHA F-LOOP Series

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.