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Chameleon Knowledge Base · The Complete Online HF Antenna Handbook

What Is Diffraction Loss?

Learn what diffraction loss is, what causes it, and how terrain and obstacles reduce radio signal strength.

Getting Started Propagation & Field Theory Reviewed 2026-07-14
Short Answer: Learn what diffraction loss is, what causes it, and how terrain and obstacles reduce radio signal strength.

Explanation

Overview Diffraction loss is the reduction in radio signal strength that occurs when RF energy bends around an obstacle rather than traveling directly between two stations. Although diffraction allows communication beyond line of sight, every diffraction event introduces signal attenuation. Common Causes Mountain ridges. Hills. Buildings. Rock formations. Dense terrain. Factors Affecting Loss Operating frequency. Obstacle height. Obstacle shape. Distance. Fresnel Zone clearance. Engineering Considerations Lower frequencies generally diffract more effectively than higher frequencies, allowing HF signals to negotiate terrain obstacles better than microwave signals. Applied to Chameleon Products Portable operators using Chameleon antennas in mountainous environments may experience diffraction loss when operating behind terrain features. Elevating the antenna often improves communication. Related Articles What Is Knife-Edge Diffraction? What Are Fresnel Zones? What Is Line-of-Sight Propagation? How Does Antenna Height Affect Performance? Related Products CHA PORTA-MAST CHA MPAS 2.0

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.