This 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.
September 1942 Radio Retailing Today
Wax nostalgic about and learn from the history of early
electronics. See articles from
Radio & Television News, published 1919-1959. All copyrights hereby
Explain Radio Fading to the Public
Neither 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:
Two Kinds of Trouble
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
Too Much of a Good Thing!
Broadcast 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.
Posted March 17, 2021
(updated from original post on 9/4/2013)