Propagation

In which we learn The Sun provides The Mirror for all the news we will hear;

Engineers can place the blame 93 million miles away. As the seminal work, The Hitchhiker's Guide to The Wireless, the one true reference puts it;

"In the innermost reaches of the Galaxy, near the unfashionable Western arm of Ursa Minor, lies a small unregarded little yellow sun. Some ninety million miles from this, in an orbit whose shape after several thousand millennia is the prototype for the rugby ball, sits a much smaller blue-green planet called Earth. The sun sends its warming rays, so God says, to ionise the rarefied upper atmosphere into layers for two carbon-based ape descendants, Mssrs Appleton and Heaviside to discover. Long after this, just after the invention of Rugby football, Marconi found that if you chuck enough radio energy at one of these layers, some of it will come down at a tremendous distance, so giving birth to short-wave radio. All this served to do no more than upset God a deal, since it was His idea in the first place..."

So there you have it - with all due credit and apology to Douglas Adams, a man whose spirit we really miss..

The current radio conditions are an Act of God. If this sounds like a cop-out, then we can only blame the insurance companies who have used the line for years.

In addition to the daily and yearly life of the sun as we see it from Earth, it also has a life of it's own. This is the eleven year long sunspot cycle. Without getting into heavy physics, the radiated energy from the sun rises and falls in this period causing a corresponding rise and fall in the ability of our ionosphere to act as a mirror reflecting far-away stations to our radio sets. In the guidance notes for ship's radio officers, it generally accepted that the cycle will see three years of rapid growth followed by eight years of gradual decline - rather like the economy. It's interesting to note that a ships "sparks" - a radio professional - has this trained into him in one paragraph. The hams - radio amateurs - find the topic all pervading, the subject of nearly every net and bulletin board. If you were just about to mail me to say that as a radio ham I am generalising again, I write this as the holder of an amateur radio callsign; G8YQL. See you further down the log. Much further...

Effects caused by solar flares, a storm on the sun and not a Seventies fashion statement, storms in the Earth's magnetic field and you have a recipe for a radio disaster or great listening. Conditions are that variable. But for the casual listener, you and I dear reader, there is but a shift of emphasis to better frequencies and the ionospheric quirks that annoy the professionals so, become our interesting catches.