ARRL

Propagation of RF Signals

Introduction

Radio waves, like light waves and all other forms of electromagnetic radiation, normally travel in straight lines. Obviously this does not happen all the time, because long - distance communication depends on radio waves traveling beyond the horizon. How radio waves propagate in other than straight-line paths is a complicated subject, but one that need not be a mystery. This page provides basic understanding of the principles of electromagnetic radiation, the structure of the Earth's atmosphere and solar-terrestrial interactions necessary for a working knowledge of radio propagation. More detailed discussions and the underlying mathematics of radio propagation physics can be found in the references listed under additional resources.  If you're looking for the ARRL Propagation Charts, you'll find them by clicking here.

The Sun, being the largest engine in our solar system, has a great effect on propagation as its "exhaust" interacts with our Earth's magnetic field. A rudimentary knowledge of sunspots, solar flares and mass ejections will help the amateur take advantage of these effects to enhance his pleasure, or understand his plight.

Articles

Tutorials

 

Propagation Reports and Forecasts

  • Radio Signal Propagation
    Many articles on how radio signals travel great distances at different frequencies. Topics include sporadic E, sunspots, troposcatter, meteor scatter, sudden ionospheric disturbances, and ground wave propagation.
  • QST Propagation Charts
    Propagation charts as they used to appear in QST. Conditions between your location and 12 regions of the world.
  • Propagation Resources
    A list of Web links concerning divers propagation topics
  • hfradio.org propagation
    This page is dynamically created from many sources using automation, and the information contained is as fresh as possible. This page will reload every 15 minutes, which will refresh any content that has changed since last viewing.
  • Near-Real-Time MUF Map
    This is a highly informative map that can be used by amateur and professional radio communicators to determine maximum usable frequencies for any world-wide path at the indicated UTC (Zulu) time. (This map is updated every 30 minutes.)
  • W1AW Propagation Bulletins W1AW, the Hiram Percy Maxim Memorial Station provides informational bulletins to Amateur Radio Operators.
  • DX-Listeners' Club Solar Terrestrial Activity Report
    The Solar Terrestrial Activity Report is generally updated once a day. The report contains a graphical view of the last 2 months' solar flux values, sunspot count and planetary A index. In addition there is information on recent solar events as well as predictions for the next days. Charts of all sunspot cycles from cycle 1 are available as well as comparisons of the most recent cycle with previous cycles
  • Sunspot Numerology
    NASA Space News
  • D-Region Absorption Prediction
    Presented by the NOAA/Space Environment Center
  • Today's Space Weather
  • Welcome to The Aurora Page
    Information, forecasts, links and images about the "Northern Lights".
  • VHF / UHF Tropospheric Ducting Forecast
  • Radio Communications Site Index
    The Basics of Radio Wave Propagation. Ionospheric Physics of Radio Wave Propagation. Pactor-II: The Most Advanced Digital Mode for HF Communications Today. Ionospheric Propagation Research with the Help of Pactor-II.
  • Wireless Network Link Analysis
    A path-loss calculator
  • VOACAP Quick Guide
    High-Frequency Ionospheric Communications Analysis and Prediction
  • HF propagation visualizer
    G4ILO, Julian Moss, has a free program that provides a “big picture” view of propagation conditions
  • Radio amateur activities of ON4SKY
    ON4SKY, Thierry Lombry, provides several illustrated articles dealing with basics of propagation, ionosopheric perturbations, models of the ionosphere and more.
  • Physics of the Aurora: Earth Systems
    An interactive learning module about the physics of aurora.
  • Paul Kelley N1BUG maintains Aurora Sentry, a page with satellite maps that show auroral activity.
  • Q-up http://q-upnow.com

    A subscription service offering real-time and forecast High Frequency (HF) radio frequencies for propagation. The service is derived from the Utah State University (USU) Space Weather Center (SWC) space weather data system.

  • NZ4O Daily MF/HF/6M Radiowave Propagation Forecast

  • Professional-grade high-frequency (3-30 MHz) propagation predictions online.

Propagation Beacons

Propagation Software