08.15.2013 03:06 PM
RF Shorts for Aug. 15, 2013
A review of RF-related news during the past week
Orbiting Copper ‘Whiskers’ Once Touted for Stable Long Range RF Propagation
Ham radio operators know that propagation can be great when the ionosphere cooperates. I remember working stations all over the United States during sporadic-E openings in a VHF contest in the late 60's. It appears that an idea surfaced to provide long distance communication at frequencies around 8 GHz about five years prior to this sporadic-E skip I enjoyed, which involved something a bit more reliable than nature. It was in the form of copper whiskers launched into space.
 
You can read about it in Joe Hanson's The Forgotten Cold War Plan That Put a Ring of Copper Around the Earth on Wired.com.
 
He writes, “A potential solution was born in 1958 at MIT’s Lincoln Labs, a research station on Hanscom Air Force Base northwest of Boston. Project Needles, as it was originally known, was Walter E. Morrow’s idea. He suggested that if Earth possessed a permanent radio reflector in the form of an orbiting ring of copper threads, America’s long-range communications would be immune from solar disturbances and out of reach of nefarious Soviet plots. Each copper wire was about 1.8 centimeters in length. This was half the wavelength of the 8 GHz transmission signal beamed from Earth, effectively turning each filament into what is known as a dipole antenna. The antennas would boost long-range radio broadcasts without depending on the fickle ionosphere.”
 
Check out his article and I think you'll agree with his comment, “In Earth’s catalog of space junk, West Ford’s bits of copper make up only a fraction of the total debris cloud that circles the Earth. But they surely have one of the strangest stories.”
 
Time Warner/CBS Dispute Boosts TV Antenna Sales
If you've been following the reports and advertisements that center around the Time Warner Cable/CBS dispute over re-transmission fees, I suspect that many readers had the same reaction I did--“go out and get an antenna.”
 
It appears many people are doing just that.
 
On NorthJersey.com staff writer Linda Moss writes CBS blackout by Time Warner boosts sales of TV antennas. “Some North Jersey retailers have seen a surge in TV antenna sales as Time Warner Cable customers look for alternative ways to pick up WCBS-TV, which was dropped by the cable company nearly two weeks ago.”
 
She reported that the manager of a local Target store reported he had sold out of one of the varieties of antennas he sold and overall antenna sales where about twice as high as usual. A RadioShack spokesman said antenna sales are up “double digits” in the New York area.
 
New Take on Spectrum Scarcity Offered
The conventional wisdom is that spectrum is scarce. I found an interesting posting by Steve Song on techcentral.co.za, Spectrum scarce? Not so fast--We’re often told that radio frequency spectrum is scarce. But is it really? Song makes this argument against spectrum as a scarce resource:
 
“A key consideration when looking at public versus private access to any resource is whether that resource is rival or not--does use of it by one person preclude use by another. Rival goods tend to become private property, whereas non-rival goods such as solar power, for example, are public goods that do not require explicit management. And, of course, there is a range of goods in between which are partially rival, such as the oceans, which are non-rival as long as care is taken to ensure the resource is tended and not overused.”
 
Song continues:
“Historically, regulators have been obliged to treat spectrum as a rival good because of interference. In fact, in order to ensure the absence of interference for television broadcasters, regulators were obliged to establish spectrum frequency no-man’s-lands between television channels to reduce the chances of stray interference. However, the now rapid evolution of both wireless technologies obliges us to reconsider how we think about spectrum and spectrum “
 
I'm not sure I agree with all his observations, but his points are worth considering. He sees spectrum efficiency increasing consistently, in a manner similar to Moore's Law. I think we're already getting close to the limits based on Shannon's “law”, making it hard to accept a law coined by Martin Cooper that argues, “spectral efficiency has doubled every 30 months since Marconi patented the wireless telegraph in 1897. The evolution of radio and antenna design has meant that with increased sensitivity we can now communicate the same information with much less power.”


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