Saturday, February 25, 2012

Diversity Fin Antenna solves longstanding problems with indoor wireless

The enthusiastic response and fast sales of the Diversity Fin Antenna have been gratifying, to say the least. Most users appreciate the convenience and performance aspects:

1. Single stand

2. Orthogonal elements virtually eliminate cross polarization nulls.

3. Superior signal constancy within the field of use.

4.Non-critical positioning relative to the stage.

5. Forward biased bidirectional dipole 90 degrees from the plane of the substrate - the dipole is not an omni (see specs here)

6. Uncorrelated orthogonally polarized LPDA with minimal cross coupling.

7. Works with all two branch systems and even with two antenna phased array systems (those that switch phase of two spaced apart antennas to provide a positive signal)

8. Safety. If it falls over, there are no sharp or hard edges to damage equipment or other objects. The corners of the dielectric cover is padded, and the cover doubles as a travel case.

9. Stows by just folding the dipole into the stow position.

10. Price

11. Polarization diversity is rapidly being adopted by telecoms, land mobile systems, urban communication systems and other RF transmission equipment due to its superior signal constancy with virtually no tradeoff  (typically 1 dB) in gain. (see this paper for a good read on why this is)

12. Designed using current Human Factors Design principles by a team with over 4 decades of antenna design experience, and over 30 antenna related patents.

RFvenue.com

Friday, February 17, 2012

The spectrum should be ours, and it still can be

by Bob Crowley




It’s not hard to find dozens of articles about the impending FCC rulings allowing much wider use of spectrum in the spaces between television broadcast stations. So-called White Spaces are a partial misnomer, as this article in Wired makes the common error of calling WiFi a white space spectrum. It isn’t.  But what is apparent, and correctly mentioned, is that the FCC and others have a naive idea of what the future of spectrum use will afford. Yes, smart cars will need radio communications to control them, of course. But this misses the point of what electromagnetic radiation afforded communications are all about. The ability to transfer large amounts of information through space is unique to EM/radio and it has taken since the late 1800s for technology to be developed that can use it in a more or less automatic fashion, instead of having radio operators find channels and manually switch frequencies.   That’s where we are today, with the basic computer capable of two-way data communication to another computer not too far away, wirelessly.

Free wifi, cellular, for all?

Now for the next step: Long range peer to peer communication, mesh networks they are sometimes called, where your laptop or smartphone jumps to another person’s laptop, and over and over it relays to the final destination. Such use requires bandwidth, and is clearly in the mind of FCC.  Wimax and LTE are other more conventional ideas of hubs and spokes connected to the conventional ISP structure of the internet, but peer-to-peer direct connections are far more delicious to think about, as they bypass the giants such as Verizon and others, at least that’s the idea.

Getting physical

We’ll see in a few years. Meanwhile, the physical layer, the part where a signal goes out into space to be collected somewhere else, will still exist unchanged. No matter what, we can say confidently, the physical part of electromagnetic radiation, propagation and collection cannot be avoided if we are to have wireless communications among us, and that means energy will have to be used, though in small amounts, and that leads to efficient antennas.(or not, as in the case of the most recent iPhone antenna fiasco)

Something has to pick up the signal, and also transmit. Battery life is entirely dependent upon the efficient, non-wasteful radiation of RF energy to the nearby or perhaps not so close connection points that are being installed everywhere.

"Spectrum Omniscience" is a Possibility

One can imagine that no matter where you are, you will have continuous, ubiquitous connectivity via mesh networks.  We will be able to  receive and send information everywhere, all the time, to everyone. There will be dive-in points held by the large carriers and perhaps smaller enterprises too, but the rules of business will change, and if we are lucky, the spectrum will be ours.

Sunday, February 12, 2012

"Bomber Stock" 4D32 tube found in Collins 32V2 Transmitter

Peter Costa holds mysterious "tube" from Bomber
February 11, 2012:  Cold War relic discovered in Massachusetts basement.

A mysterious 4D32 transmitting "tube" produced by Raytheon was found this week with the curious label "bomber stock" in a cold-war era Collins transmitter owned by ham radio operator Peter Costa, W1ZZZ, of Massachusetts.

The rare glass tube had been hidden from view under the cover for decades, and not recognized as possibly part of the Strategic Air Command equipment list, presumably led by the famous "We'll bomb them back to the stone age" General Curtis Lemay, who ran "SAC" and also for Vice President of the United States with George C Wallace.

"Tubes" were produced in the early days of electronics by a few manufacturers using primitive equipment. Prior to the 1950s, people gathered together and listened to "radio" - the old term for what many refer to as "wireless" today.

Raytheon was a prolific manufacturer of communications equipment for the military in the 1950 through 1980 time frame, and still produces guidance systems, communications systems, missiles, and various aerospace items, such as surveillance satellites.

The RK-4D32 is a robust and once rare transmitting tube having characteristics similar to a pair of 6146 tubes. The 4D32 was used in a couple of civilian transmitters such as the Collins 32V1, 32V2 and 32V3 AM transmitters, and some others, but was always a scarce tube and hard to find. This was not much of a problem since they tend to last about 50 years in intermittent service, perhaps longer. In the late 70s, Raytheon produced the last run of these and other tubes and they sat in warehouses until about 1997 when they were sold to surplus dealers, and for that reason they are now cheap and abundant.

Cellular - Free of Charge?

Peter Costa, who holds a license issued by the Federal Communications Commission, and call sign "W1ZZZ" is one of the growing number of civilian spectrum users who directly access the airwaves to chat, send messages and keep in touch with friends, free of charge.  Peter and his fellow users do not pay Verizon, AT&T or any other carrier, and enjoys free anytime access to large portions of spectrum which he shares with other users.

As public access to the spectrum grows as a way to communicate, experts expect resistance from cellular carriers such as Verizon. "Eventually consumers will have the last laugh." Says Robert J Crowley who invents antenna systems to improve spectrum efficiency and also accesses the airwaves for free, "The spectrum is a natural resource. It  is not like land and should not be sold, and Congress is charged with the duty of holding it in trust for the public use. It can never be controlled by man completely, and some day, perhaps in the next decade, we will see the emergence of public access systems that replace cellular as we know it."

Wednesday, February 08, 2012

Wednesday, February 01, 2012

Edd Kalehoff



One of my favorite composers, mentioned several times on this blog, is Edd Kalehoff. He wrote the Monday Night Football theme (Heavy Action), the Price is Right, various ABC and NBC themes and this one.