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.
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. A good basic understanding of this can be had by reading the article "The Sun, the Earth, the Ionosphere." See also the list of other articles on propagation.
You can get custom professional-grade high-frequency (3-30 MHz) propagation predictions online.
Current HF Propagation Charts
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
These predictions are for a solar flux of 115. The date issue has been fixed!
March 2011
February 2011
These charts are for a predicted solar flux of 85.
January 2011
These charts have are for a predicted solar flux of 101--while there has been more sunspot activity, the solar flux is still less than expected.
East Coast January 2011
Mid-USA January 2011
West Coast January 2011
Alaska/Hawaii January 2011
December 2010
These charts may look familiar--they are precisely the same charts we ran last year--the upturn in solar activity has been slower than expected. These charts are for a predicted solar flux of 104.
Yes, these charts have a date of 2009 instead of 2010--we are awaiting a software upgrade in the lab.
November 2010
These charts may look familiar--they are precisely the same charts we ran last year--the upturn in solar activity has been slower than expected. These charts are for a predicted solar flux of 101.
Yes, these charts have a 2009 date on them--we are awaiting a software upgrade.
October 2010
These charts may look familiar--they are precisely the same charts we ran last year--the upturn in solar activity has been slower than expected. These charts are for a predicted solar flux of 98.
Yes, we know the charts say 2009 instead of 2010--the lab is awaiting a software upgrade.
September 2010
These charts may look familiar--these are precisely the same charts we ran last year--the upturn in the sunspot activity has been slower than expected. These charts are for a predicted solar flux of 95.
Yes, these have a 2009 date, as we are waiting for a software upgrade in the lab to fix this issue.
August 2010 Charts
These charts may look familiar--they are precisely the charts we ran last year--as the sun's sunspot and solar flux activity has been a lot lower than expected. These charts are for an expected solar flux of 92.
Yes, we are aware of the wrong date in the charts--we are currently awaiting some software updates to improve the graphics capability of the lab.
Where can I find solar data?
Mark Downing, WM7D, has graphs of solar data on his web site.
Home >> Technology >> Radio Technology Topics >> Propagation of RF Signals >> Propagation