Doug Lung /
11.22.2013 10:13 AM
RF Shorts for Nov. 22, 2013
A review of RF-related news during the past week
DOD/NAB Nearing 2 GHz Spectrum Accord
Bryce Baschuk, at Bloomberg BNA reports DOD Nears Spectrum Sharing Deal With Broadcasters for Commercial Auction. Baschuk writes, “'Under the terms of the agreement, Defense is planning to transition many of its communications systems related to aircraft pilot training, drones, missile guidance and others from the 1755-1780 MHz band onto the 2025-2110 MHz band on a shared basis. Broadcasters currently use the 2025-2110 MHz band for broadcast auxiliary services to transmit live video content from breaking news scenes, among other uses.”

An agreement between broadcasters and DOD (Dept. of Defense) to share the 2 GHz broadcast auxiliary service (BAS) band could reduce pressure from the wireless industry to reallocate part of the band for wireless broadband.

Graphene Technology Used to Construct Tiny FM transmitter has an interesting article by Ranjini Raghunath reporting Engineers Create Smallest FM Radio Transmitter Using Graphene. Raghunath writes, “The Columbia team used the graphene VCO [voltage conteolled oscillator] to send and receive audio signals at a frequency of 100 MHz, which falls within the FM radio bandwidth (87.7 to 108 MHz). Both simple and complex music signals… were used to tune the VCO’s output. The team also recovered the audio signal using an ordinary FM radio receiver, and found that it 'faithfully reproduced' the original signal.”

James Hone, professor of Mechanical Engineering and senior author of the study published online Nov. 17 in the journal Nature Nanotechnology, said, “This device is by far the smallest system that can create such FM signals.”

The research was conducted at Columbia University. Additional information and images are available in the Columbia news release Columbia Engineers Make World’s Smallest FM Radio Transmitter. Unfortunately a subscription is required to read the study Graphene mechanical oscillators with tunable frequency but you can browse figures from the study.

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Posted by: Anonymous
Fri, 11-22-2013 05:38 PM Report Comment
The Graphene story brought back a fond memory... Back in 1976, a great engineer and fine man, Harold Wagner, Chief Engineer, WMVS-WMVT PBS Milwaukee, developed a lambda diode based transmitter for broadcast on the FM band. We used it as a repeater for our headset system at a large, spread out "auction" venue at the Wisconsin State Fair grounds. Harold was quite a clever engineer and the system worked beautifully. Well, even better than we thought! We got a call and were told one of our engineers listened to us in his car about a mile away! Harold made a quick field modification and it still worked GREAT, under the expansive auction roof! He clipped the antenna. :-)

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