Turn HF Guesswork Into Strategy
If you’ve ever tuned across a silent HF band and wondered whether the band is really closed, or when to anticipate the next potential opening, this book is for you.
VOACAP is the propagation prediction engine trusted by international broadcasters such as the Voice of America, government agencies, and amateur radio operators around the world. VOACAP Online brings that professional-grade engine to your web browser, making sophisticated HF propagation forecasting available with just a few clicks. Written by Jari Perkiömäki, OH6BG, one of the creators of VOACAP Online, VOACAP: Unlocking the Ionosphere is the practical guide that shows you how to turn those predictions
into confident operating decisions.
The book takes you from your first click to a complete operating plan, with deep dives for readers who want to understand why the model says what it says, and a clear practical path for operators who simply want to know what to do tonight. You’ll learn to read the colored wheels and charts the way a pilot reads a weather briefing: not as decoration, but as the basis for a plan. You’ll know when to trust the prediction, when to cross-check it against another propagation tool, and when to put the laptop down and trust your ears.
Inside, you’ll learn how to:
Build propagation predictions for any path on Earth, on any HF band, at any hour.
Understand the three key indicators together: Is the band open? How strong will the signal be? How reliable is the path?
Recognize where VOACAP performs well, and where it has limitations.
Use VOACAP alongside complementary prediction tools to gain greater confidence in your
operating plans.
Replace guesswork with strategy, whether you’re planning a contest operation or simply deciding which band to try next.
Written for newly licensed amateurs, experienced DXers, contest operators, DXpedition planners, and curious shortwave listeners alike, VOACAP: Unlocking the Ionosphere transforms one of amateur radio’s most powerful — and often misunderstood — tools into an essential part of every HF operator’s station.
The ionosphere is up there, doing what it has always done. Now you have the tools to use it. Go explore.
About the Author: Jari Perkiömäki, OH6BG, has been an active amateur radio operator and shortwave listener for more than 45 years and is based in western Finland. In the early 2000s, he created VOACAP Online with James Watson, MØDNS, and Juho Juopperi, OH8GLV, under the mentorship of George Lane, who guided VOACAP’s development during the era of international shortwave broadcasting, and Greg Hand, its principal software architect.
Product Details
Softcover: 244 pages
Publisher: The American Radio Relay League, Inc.
Copyright: First Edition, First Printing (2026)
Language: English
ISBN: 978-1-62595-254-7
Shipping Weight: 1 pound