On June 10, a listener in Danville, IL picked up 90 seconds of NHPR signal. A station’s radio wave “footprint”, or estimated range, is generally considered to extend only about as far as the eye can see from the point of the antenna, but Danville is just under a thousand miles away. It would take more than a good pair of binoculars to put Danville within range of sight; so how did this happen?
Amateur radio enthusiasts, known as “DXers”, describe what our listener caught a glimpse of as an “E-Skip”.
To understand what that is you need to head way up into the air.
Under normal conditions, radio travel through the ionosphere, around 55 to 100 miles above the Earth’s surface.
Radio host and internationally recognized DXer Glenn Hauser says when weather conditions are right, patches of especially reflective air particles start to form, causing E-Skips.
Hauser: Yes, this was certainly sporadic E-Skip, which is something that happens primarily in the summers. We’re at the peak of the annual season right now…TV signals on the lower channels, and FM signals which normally have limited coverage of course to their ground wave area are reflected off these patches which develop up in the ionosphere and come back down, typically about a thousand miles away.
Basically, a bit of NHPR’s radio waves hit some ionized particles, which “bent” or bounced all the way to Danville.
Where did those charged particles come from?
Hauser: What actually causes sporadic E-Skip is a matter of great debate. No one is really sure yet. It does seem to be related to weather patterns lower in the atmosphere, such as storms and lightening which may affect higher regions above. There’s some correlation, for instance, half-way between the transmitting and receiving point there’s often some type of storm going on.
So in early summer, when rising temperatures start to stir up unsettled weather, it creates the perfect storm, literally, for radio signals to be unpredictable.
Whatever the reason, it seems that the next few weeks may prove ideal for picking up on this mysterious phenomenon. E-Skip can bridge over two thousand miles, so keep your ears open: you may just be lucky enough to hear some authentic Cuban jazz.