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May 1946 Radio-Craft
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
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Earth-moon-earth
(EME) radio communications was a big deal in the 1940s and up through the early
artificial satellite era of the 1960s. The moon is technically a satellite, too,
but it is far from ideal for reflecting radio signals. Amongst its negatives is
signal attenuation due to extreme distance (225,623 at minimum when directly overhead
at the lowest point in orbit - farther when near the horizon), low
coefficient
of reflectivity (from about 0.03 at 4 cm to 0.1 at 10 m), and it is
in constant motion (position tracking and Doppler correction required). Of course
that is part of the desirable challenge to today's Amateurs, but back in the day EME was considered a desirable
option for military strategic communications. 1946 was the year EME really got started,
as noted in this 1946 issue of Radio-Craft magazine quip. In other news,
RCA president and U.S. Army Brigadier General David Sarnoff (mostly an honorary
title) was awarded a Medal for Merit based on his voluntary service during World War II.
And, speaking of Amateur Radio (see above), Hams were once again permitted to transmit
as the result of the end of the war, during which transmission had been prohibited.
Radio-Electronics Monthly Review
Signals transmitted from a single point on the earth would be
reflected back from the moon in a broad wave which would almost cover a hemisphere.
Broadcasting Via the Moon from one part of the earth to another,
described in last month's issue of Radio-Craft (page 502) as a
Gernsbackian prediction from the year 1927, may become a reality if a plan announced
last month by Federal Telephone and Radio Corporation is put into effect. Scientists
of that company consider the establishment of communication between distant points
on the earth by using the moon as a reflector "entirely feasible in the not-too-distant
future."
It is obvious that a transmission emanating from any point, beamed at the moon
and reflected back to the earth, would strike all points on the side of the earth
turned towards the moon with substantially equal intensity. Since the radio waves
strike the receiver from above, natural obstacles between the transmitter and receiver
would have no effect. Therefore, the blocking action of the curvature of the earth,
mountains, cities and other obstacles to high frequency line-of-sight transmission
will be eliminated.
The range of a powerful television broadcasting station would be hemispheric.
Reception American television broadcasts would be equally good throughout South
America, Canada and Alaska, as well as Europe and a large part of the Pacific. The
only requirement would be that the receiver be within sight of the moon at the same
time as the transmitter. More remote stations would therefore, have less available
time for reception, and the maximum operating time for any station would be 12 hours
per day and regularly changing. This is a factor with which radio and television
have not heretofore had to contend.
The advantages of moon-reflected transmission would be manifold, especially those
due to the use of very high frequency transmission allowing for a considerable number
of channels. At present the band width of the receiver is narrow, thereby limiting
the transmission to code messages, but probably future developments will overcome
this disadvantage, when higher power transmitters become physically and economically
feasible. Fantastic developments may then enter the realm of reality.
Major General H. C. Ingles and Brigadier General Sarnoff.
The Medal for Merit was presented last month to Brigadier General
David Sarnoff, RCA's president, by Major General H. C. Ingles, Chief Signal Officer
of the Army, who represented President Truman at a presentation ceremony held at
Radio City, New York.
General Sarnoff was previously awarded the Legion of Merit on October 11, 1944,
for "exceptional meritorious conduct in the performance of outstanding service"
when he was on military service overseas. The present decoration was a tribute to
his civilian activities as head of a great radio corporation. The citation, signed
by President Truman, said (in part): Mr. Sarnoff placed the full resources of his
company at the disposal of the Army whenever needed, regardless of the additional
burden imposed upon his organization. He encouraged key personnel to enter the service,
and at his direction RCA engineers and technicians rendered special assistance on
numerous complex communications problems. He fostered electronic advances which
were adapted to military needs with highly beneficial results. The wholehearted
spirit of cooperation which Mr. Sarnoff inculcated in his subordinates was of inestimable
value to the war effort.
Ham Stations are again being licensed, it was announced last
month by the American Radio Relay League. The FCC has resumed licensing of amateur
radio stations after suspending this service at the outbreak of the war.
Prior to Pearl Harbor, there were 60,000 amateur radio station licenses in the
United States. It is estimated that this number will increase to 250,000 in the
next five years due to the upsurge of interest in amateur radio communication created
by the war.
 Mesons produced artificially for
the first time in a laboratory were announced last month by General Electric engineers.
Using X-rays from the company's new 100,000,000-volt betatron, physicists have succeeded
in producing this short-lived particle heretofore found only far above the earth's
surface. The betatron has opened to science a new energy range, between 40 and 100
million volts.
The meson, hitherto known only through cosmic ray studies, is a particle considerably
more massive than the electron, though lighter than the proton. Mesons are produced
in the atmosphere high above the earth's surface by the primary cosmic radiation
from outer space and last, on the average, but a few millionths of a second.
Posted May 25, 2021
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