June/July 1940 National Radio News
of Contents] These articles are scanned and OCRed from old editions of the
National Radio News magazine. Here is a list of the
National Radio News articles I have already posted. All copyrights are hereby acknowledged.
National Radio News was published bi-monthly by the folks at
National Radio Institute (NRI). NRI used to be a major training
center for electronics technicians beginning in the early part of the
20th century. This article was provided for them by the Federal Communications
Commission (FCC) as a synopsis of radio frequency spectrum allocations
at the time. Compare a 1940 spectrum allocation chart (just a simple
description here) to one for 2014 and you will see a remarkable
in not just the number of bands, but in the extension of the frequency
range. This link produces the
FCC Online Table of Frequency Allocations
(April 4, 2014) document, and this one
is a more user-friendly equivalent graphical chart recently published
Wireless Design & Development magazine.
BBTW, the picture below has nothing to do with the article. It appeared
on the table of contents page and I thought it would make a good addition
since the article itself had no image.
Radio Frequencies and Their Allocation
article was released to National Radio News by the Federal Communications
Commission, Washington, D. C.
The radio spectrum, or radio waves form one portion of the total
electromagnetic spectrum. The electromagnetic spectrum covers eight
different classes of radiation-electric waves, radio waves, infra-red,
visible light, ultra-violet, X-rays, gamma rays, and secondary cosmic
The emission of this energy may be likened to the expanding ripples
of water suddenly disturbed by a thrown stone. However, electromagnetic
energy travels in all directions.
Since electromagnetic radiations have a common speed (that of light),
their only difference is in frequency and wave length. "Frequency" may
be characterized as the number of these waves per second, and "wave
length" as the distance between successive waves.
The divisions between the various classes of electromagnetic radiations
are not definite. The lines of separation are based largely upon the
effects and the particular method of producing the various emissions.
Under certain conditions, some of these electromagnetic impulses may
be seen, felt, or heard. Of the eight classes of electromagnetic radiations,
that portion classed as "radio waves" covers a relatively small part
of the total electromagnetic spectrum.
Radio facilities are extremely limited. In order to provide the maximum
possible service for the benefit of the public, it is necessary to control
and restrict the use of the available channels. As transmission by radio
waves spans great distances, it has been found necessary to have international
agreement on the proportion of available channels to be allocated for
particular services. To prevent interference within our own country,
it is necessary to further apportion the frequencies in the best interests
Besides the standard broadcast channels. our radio spectrum is shared
by other primary services, such as: fixed, marine, aviation, emergency,
amateur, miscellaneous, experimental, Government, and broadcast services
other than standard broadcast. These general service allocations cover
various classes of station, including: relay, international broadcast,
high frequency broadcast, noncommercial education, facsimile, television,
point-to-point telephone and telegraph, agriculture, press, coastal,
telegraph and telephone, ship, aircraft, aeronautical, blind landing
systems, airport, municipal and State police, marine fire, forestry,
geological, mobile press, motion picture, amateur phone, telegraph and
television, as well as experimental classes of stations.
The present useful radio spectrum, in which channels are now allocated,
ranges from 10 to 300,000 kilocycles, or in terms of wave lengths from
30,000 meters to 1 meter. That portion below 100 kilocycles is popularly
referred to as "long waves"; from 100 kilocycles to 550 kilocycles as
"medium long waves'"; from 550 to 1600 kilocycles as "broadcast" ; 1600
to 6000 kilocycles as "medium short waves"; 6,000 to 30,000 kilocycles
as "short waves"; and above 30,000 kilocycles as "very short" or "ultra-short
The band below 100 kilocycles is occupied by Government and commercial
long wave fixed service stations. From 100 kilocycles to the beginning
of the broadcast band at 550 kilocycles we have the medium long wave
stations, as follows: 100 to 200 kilocycles - Government and private
ship, coastal, and fixed service stations.
200 to 400 kilocycles - primarily Government aids to navigation,
such as radio navigation for aircraft, and radio beacon service to ships,
interspersed with airport on 278 kilocycles, direction finding on 375
kilocycles, and miscellaneous fixed stations.
400 to 550 kilocycles - Government and commercial ship and coast
stations in the maritime service centered near the international calling
and distress frequency of 500 kilocycles (600 meters).
The rest of the spectrum from the end of the "broadcast" band at
1600 kilocycles, involving the so-called "medium short," "short," and
"ultra-short" wave bands, could be pictured as a many layered sandwich,
with police, amateur, aviation. Government, ship, coastal, broadcast,
mobile press, special services, experimental television fixed, forestry,
and all other classes of stations providing varying depths of filling.
Of course, this does not mean that all these bands are completely
filled. Radio communications is still undergoing change, and the Federal
Communications Commission, in licensing individuals and firms to use
the public's radioways, is charged with preparing for the future, as
well as for the present. Hence, some channels are held open for future
developments, while others already allocated, are subject to shift with
Posted April 8, 2014