Propagation Resource Center :: NW7US :: HFRadio.org
To view the best working frequency by time, check out:

+ Current Optimal Frequencies

If you are using software utilities such as Ace-HF, that require a "smoothed" sunspot number, or flux index, check out:

+ Predicted SMOOTHED Sunspot Number And Radio Flux Values with Expected Ranges

+ The eAlert (email) Propagation Reports

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This page was rendered on 16-Jul-25 0705 UTC.

Sun Spots: 146 as of 07/15/2025 :: Flux: 139 | Ap: 23 | Kp: 3.00
Solar Wind: 588 km/s at 2.0 protons/cm3, Bz is 6.0 nT
(Jul 16, 2025 at 0650 UT) :: [ Other Kp graphs ]

On 2025 Jul 16 0659Z: Bz: 2.9 nT
Bx: -1.9 nT | By: 5.7 nT | Total: 6.7 nT
[ Real-Time Solar Wind data dials ]

Most recent satellite polar pass:
Centered on // : UTC
Aurora Activity Level was at UTC
visit noaa for latest.

X-ray Solar Flares:
6h hi [C5.0][0351Z 07/16] 24h hi [C5.0][0351Z 07/16]

Global HF Propagation Conditions for 0400Z on 05 May, 2021
High Latitude: Normal
Middle Latitude: Normal
Low Latitude: Normal

Summary for last 24 hours:
Space weather for the past 24 hours has been minor.
Geomagnetic storms reaching the G1 level occurred.

Forecast for next 24 hours:
No space weather storms are predicted for the next 24 hours.

If there are warnings, they are listed lower on this page.
Some useful books on Propagation:

+ Check this one out: The Friendly Ionosphere - by Crawford MacKeand, WA3ZKZ. Crawford MacKeand is a Chartered Electrical Engineer in the United Kingdom, and before his final retirement from consulting engineering, was a registered Professional Engineer in the State of California. His working life encompassed microwave radar and telecommunications from HF to audio, while his amateur radio experience is from the early 1950s to the present, licensed at various times as G4ARR, WA2ZVX, WA3ZKZ and VP8CMY.

The publication of "The Friendly Ionosphere" fills a gap in radio's literature. While strongly based in the science, the author makes some very important aspects of the subject understandable from a users' view. Many years of professional experience in telecommunication engineering, as well as in amateur radio, ensure that the book is valuable and accessible to the ham operator and yet is particularly well documented for the field engineer.

The examples which illustrate applications in radio propagation include the still controversial questions of whether Marconi really did hear transatlantic signals in 1901, and where Amelia Earhart was when her transpacific flight ended with a massive but unsuccessful mid-ocean search by the US Coast Guard and Navy in 1937.
I write the propagation columns for the following magazines:

CQ Magazine CQ Magazine America's fastest growing magazine for the active ham radio operator. CQ is the world's leading independent magazine devoted to amateur radio. For more than a half-century, CQ has been on ham radio's leading edge -- the first to promote mobile operating (in the 1950s), semiconductors (in the 1960s) and packet radio -- the original e-mail (in the 1980s). The amateur satellite program got its start with an idea in the pages of CQ!

CQ VHF Magazine CQ VHF Magazine It is back! May 2002 saw the return of this quarterly magazines that focuses on amateur radio above 50 MHz. Articles and columns target both the beginner as well as the expert.

Popular Communications Magazine Popular Communications Magazine Exciting reading for the shortwave and scanner listener. It features authoritative information on scanner monitoring of police, fire, utility and aircraft transmissions as well as short wave listening, monitoring short wave digital, fax and teletype broadcasts, cb radio, alternative radio, clandestine radio, telephones and wiretapping, bugging, surveillance, pirate broadcasters, military communications, amateur radio, satellite tv reception, radio history and nostalgia.

Monitoring Times Magazine Monitoring Times Magazine Contains news, information, and tips on getting more out of radio listening. Do you own a radio, a shortwave receiver, a scanning receiver, or a ham radio? Then Monitoring Times� is your magazine! Open a copy of MT, and you will find 92 pages of news, information, and tips on getting more out of your radio listening. In fact, it's the most comprehensive radio hobby magazine in the U.S. Packed with up-to-date information concisely written by the top writers in the field, Monitoring Times� is your foremost guide to profiles of broadcasting and communications installations; home projects; and tips on monitoring everything from air, sea, and space to distant ports of call.


Radio Antennas and Propagation - book Radio Antennas and Propagation : Radio Engineering Fundamentals by William Gosling


The Propagation of Radio Waves - book The Propagation of Radio Waves : The Theory of Radio Waves of Low Power in the Ionosphere and Magnetosphere by K. G. Budden (Preface)


Radio Frequencies and Principles and Applications Radio Frequency Principles and Applications : The Generation, Propagation, and Reception of Signals and Noise by Albert A. Smith


The Shortwave Propagation Handbook (Cq Technical Series) by Cohen

The New Shortwave Propagation Handbook by George Jacobs, Theodore J. Cohen, Robert B. Rose

Radio Amateurs Guide to the Ionosphere by Leo F. McNamara

Electromagnetic Waves in Stratified Media (IEEE/OUP Series on Electromagnetic Wave Theory) by James R. Wait

ARRL 2003 Handbook The ARRL Handbook for Radio Amateurs 2003 by Dana George Reed (Editor), ARRL


ARRL Antenna Handbook - 19th Edition The ARRL Antenna Handbook - 19th Edition by R. Dean Straw (Editor) (Book and CD-ROM)