Explain Radio Fading to the Public
September 1942 Radio Retailing Today Article
is a great primer for anyone looking for an easily understandable way to explain the basics of radio signal fading
to acquaintances, or for that matter to understand it yourself if you don't already. As I review the material for
taking my amateur radio General Class exam, there is information about atmospheric absorption in the various ionospheric
layers during daytime and nighttime. Prior to studying the manual, I either never knew or once knew but have forgotten
about the upper F1 and F2 layers combining into a single layer at night when the sun's radiation and particle bombardment
is blocked by the earth. This article doesn't go that deep into the physics, but it does a good job of making a
complex topic simple enough for the layman - although if you're trying to explain fading to politicians, well,
don't even bother.
Explain Radio Fading
to the Public
Radio Sets Nor Station to Blame for After-Dark Distortion
Beginning this month, Nature will again be giving
broadcast listeners extraordinary reception. After nightfall, the whole broadcast spectrum will again be filled
with far-off stations, many of them roaring in as strong as "locals."
This means that our radio-reflecting-layer,
100 miles up in the sky, is working as an excellent radio mirror again.*
But such "good reception," as we enjoy
at present, also brings some annoying troubles to broadcast listeners. These are twofold:
1. Distant stations come in strong, right alongside familiar local stations, and so
cause crosstalk and "monkey chatter" on familiar local channels.
2. Nearby high-power stations (60 to 100
miles away) have their sky waves so strongly reflected by the excellent sky mirror, that their reflected waves (traveling
a path 150 miles longer) reach the listener out-of-step with the same station's direct-wave he ordinarily hears.
This conflict of the two sets of waves, if of equal strength, may produce annoying total fading. Or, certain audible
frequencies may be suppressed, so that at intervals the announcer "sounds as if he had a mouthful of hot mush,"
and a fine orchestra tinkles like a Chinese band!
Too Much of a Good Thing!
listeners hearing such interference, usually blame their sets.
But neither the set nor the broadcast station
is at fault! Nor is the set maker, the dealer or the radio repairman!
Nature herself is to blame, by temporarily
making her reception conditions too good, - so that we suffer from the spillover. Fortunately, the trouble occurs
only after dark, and usually for limited periods.
Try This Solution
A very long
antenna, or a pickup from telephone wires will sometimes help at the receiving end. This affords pickup from a number
of points, so that fading at anyone point is neutralized.
Or the listener can tune to stations less than
60 miles distant, whose reception is unimpaired. He also will find during such distortion periods that he has new
and almost unlimited choices among stations over 150 miles away, for on such nights these distant broadcasters,
including many never before heard, will be found coming in like locals.
"This is to be expected, now that
sunspots are at a minimum in their 11-year cycle. for it is the electron projectiles from the sunspots which shatter
the radio mirror and so interfere with long-distance reception.
September 4, 2013