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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

Optimizing the Coupling Loop

The F-LOOP coupling loop transfers energy between the feed line and the resonant radiator. Its diameter, position, plane, shape, feed routing, and relationship to the main loop control the match.

Product Installation Guides CHA F-LOOP Series Reviewed 2026-07-14
What matters in the field: The F-LOOP coupling loop transfers energy between the feed line and the resonant radiator. Its diameter, position, plane, shape, feed routing, and relationship to the main loop control the match.

What the operator is controlling

The F-LOOP 3.0 guide names 6.5-, 7-, and 8-inch coupling loops for specific standard, rigid, and booster configurations. Those pairings are part of the antenna design.

Where people get into trouble

Bending, rotating, or substituting the coupling loop merely to force a low SWR can change current distribution and mask loss. The lowest number is not automatically the best radiating state.

A repeatable field method

Start with the exact named coupling loop, keep it circular and coplanar as shown, route coax down the mast, tune the radiator first, and diagnose changes one mechanical variable at a time.

Product boundary

These F-LOOP instructions preserve the documented discontinued CHA F-LOOP 3.0 system for existing owners. They do not transfer hardware, tuning, power, or compatibility claims to the separate pre-production CHA F-LOOP 4.0.

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