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.
- The Sun, the Earth, the Ionosphere:
What the Numbers Mean, and Propagation Predictions--a brief introduction to propagation and the major factors affecting it. By Carl Luetzelschwab, K9LA
- An Introduction to Gray-Line DXing
QST November 1992, pp. 80-82
The transitions from darkness to daylight and daylight to darkness cause drastic changes in the ionosphere. Use this to your DX advantage.
- Catch a Falling Star
QST October 1997, pp. 63-67
A Beginner's guide to meteor-scatter communication.
- Sporadic E--A Mystery Solved? Part 1
QST October 1997, pp. 39-41
One of the world's leading ionospheric scientists explains the physics of sporadic E.
- Sporadic E--A Mystery Solved? Part 2
QST November 1997, pp. 38-42
- HF Propagation: The Basics
QST December 1983, pp. 11-15
Say it's 10 P.M. in Savannah, and you'd like to reach out and QSO someone in southern Europe. A solid knowledge of how signals travel will help you decide if you've got a fighting chance.
- Radio Waves And Communications Distance
QST, January 1985, pp. 31-33
- Here Comes the Sun
QST, Lab Notes, October 1996, pp. 74-75
- Radio Waves and the Ionosphere
QST, November 1999, pp. 62-64
- Propagation Broadcasts and Forecasts Demystified
QST November 1991, pp. 20-25
- ARLP029: Propagation de K7VVV
W1AW broadcasts a weekly Propagation Bulletin. In this one Tad Cook, K7RA, formerly K7VVV, gives a summary of what the numbers in a propagation forecast mean and how they are compiled.
- The Brendan Trophies: Insights for the New Millennium
QST August 2002, pp. 36-39
Can amateurs cross the Atlantic on 144 MHz without satellites or moonbounce?
- Understanding Solar Indices
QST September, 2002, pp. 38-40
When someone tells you that the flux is up to 200 and the K is 3, do you know what they are talking about? You will after you read this article!
- What is VOACAP Trying to Tell Me?
A Presentation to The Yankee Clipper Contest Club Feb. 1, 2003, Milford, CT, by Dean Straw, N6BV, Senior Assistant Technical Editor, ARRL
- Why We Stack ‘Em! Covering All the Angles
A Presentation to The Yankee Clipper Contest Club, Feb. 1, 2003, Milford, CT, by Dean Straw, N6BV, Senior Assistant Technical Editor, ARRL
- Microwave Propagation in the Upper Troposphere
QEX July/August, 2003
Amateur microwave work need not be restricted to operation
- Propagation Planning for DXpeditions
6 Steps for a More Successful Trip by Carl Luetzelschwab K9LA
- Propagation Planning for Contests
Using Propagation Predictions to Develop a Band Plan by Carl Luetzelschwab K9LA
- Practical Radio Aurora
QST March 1990, pp 20-25. While solar events such as coronal mass ejections can seriously disturb HF propagation, the same events can also enhance VHF propagation.
- An Introductory Tutorial to W6ELProp (96,641 bytes, PDF file)
A Guide to Running Your Own Propagation Predictions, by Carl Luetzelschwab, K9LA. W6ELProp is named after the amateur call sign held by Sheldon C Shallon.
- An Introductory Tutorial to VOACAP (92,076 bytes, PDF file)
A Guide to Running Your Own Propagation Predictions, by Carl Luetzelschwab, K9LA
- The Precursor Method of Predicting Solar Cycles (15,958 bytes, PDF file)
by Carl Luetzelschwab, K9LA
- Electronics Technician Volume 7—Antennas and Wave Propagation NAVEDTRA 14092 Large 3.11MB download.
- VHF/UHF/Microwave Radio Propagation: A Primer for Digital Experimenters
This paper attempts to provide some insight into the nature of radio propagation in that part of the spectrum (upper VHF to microwave) used by experimenters for high-speed digital transmission.
Steve Nichols G0KYA and Alan Melia G3NYK wrote a series of propagation articles for the RSGB that is now an ebook. It can be downloaded from Steve Nichols’ blog.
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 LX4SKY Thierry Lombry, provides several illustrated articles dealing with basics of propagation, ionosopheric perturbations, models of the ionosphere and more.
- Paul Kelley N1BUG maintains Aurora Sentry, a page with satellite maps that show auroral activity.
Professional-grade high-frequency (3-30 MHz) propagation predictions online.
- Ham CAP 1.5
HF propagation prediction tool for Amateur Radio. Freeware by Alex Shovkoplyas, VE3NEA.
- HF Propagation Models from NTIA/ITS
U.S. Department of Commerce NTIA/ITS Institute for Telecommunication Sciences High Frequency Propagation Models. The package includes ICEPAC, VOACAP, and REC533. Freeware. The software is also available from the NTIA website, although NTIA only features older versions.
- Radio Mobile Freeware by VE2DBE
This software by Roger Coude VE2DBE a tool used to predict the performance of VHF and UHF radio systems.
PropView uses the included IonCap propagation prediction engine to forecast the minimum and maximum useable frequencies between two locations over a specified 24 hour period.
- ACE-HF Professional Propagation Software for HF Radio Operators
QST Product Review, November 2002
- DX Atlas by VE3NEA (Afreet Software, Inc.)
Alex Shovkoplyas VE3NEA provides this software program.