Radio-Electronics Monthly Review
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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.
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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